Kimia Kahrizi

Publications of Kimia Kahrizi

• Mutations in NSUN2 Cause Autosomal- Recessive Intellectual Disability.

  Authors: Lia Abbasi-Moheb, Sara Mertel, Melanie Gonsior, Leyla Nouri-Vahid, Kimia Kahrizi, Sebahattin Cirak, Dagmar Wieczorek, M Mahdi Motazacker, Sahar Esmaeeli-Nieh, Kirsten Cremer, Robert Weißmann, Andreas Tzschach, Masoud Garshasbi, Seyedeh S Abedini, Hossein Najmabadi, H Hilger Ropers, Stephan J Sigrist, Andreas W Kuss

  American journal of human genetics. 04/2012;

  With a prevalence between 1 and 3%, hereditary forms of intellectual disability (ID) are among the most important problems in health care. Particularly, autosomal-recessive forms of the disorder haveWith a prevalence between 1 and 3%, hereditary forms of intellectual disability (ID) are among the most important problems in health care. Particularly, autosomal-recessive forms of the disorder have a very heterogeneous molecular basis, and genes with an increased number of disease-causing mutations are not common. Here, we report on three different mutations (two nonsense mutations, c.679C>T [p.Gln227(∗)] and c.1114C>T [p.Gln372(∗)], as well as one splicing mutation, g.6622224A>C [p.Ile179Argfs(∗)192]) that cause a loss of the tRNA-methyltransferase-encoding NSUN2 main transcript in homozygotes. We identified the mutations by sequencing exons and exon-intron boundaries within the genomic region where the linkage intervals of three independent consanguineous families of Iranian and Kurdish origin overlapped with the previously described MRT5 locus. In order to gain further evidence concerning the effect of a loss of NSUN2 on memory and learning, we constructed a Drosophila model by deleting the NSUN2 ortholog, CG6133, and investigated the mutants by using molecular and behavioral approaches. When the Drosophila melanogaster NSUN2 ortholog was deleted, severe short-term-memory (STM) deficits were observed; STM could be rescued by re-expression of the wild-type protein in the nervous system. The humans homozygous for NSUN2 mutations showed an overlapping phenotype consisting of moderate to severe ID and facial dysmorphism (which includes a long face, characteristic eyebrows, a long nose, and a small chin), suggesting that mutations in this gene might even induce a syndromic form of ID. Moreover, our observations from the Drosophila model point toward an evolutionarily conserved role of RNA methylation in normal cognitive development.

• Spectrum of GJB2 (Cx26) gene mutations in Iranian Azeri patients with nonsyndromic autosomal recessive hearing loss.

  Authors: Behzad Davarnia, Mojgan Babanejad, Zohreh Fattahi, Nooshin Nikzat, Niloofar Bazazzadegan, Akbar Pirzade, Reza Farajollahi, Carla Nishimura, Khadijeh Jalalvand, Sanaz Arzhangi, Kimia Kahrizi, Richard J H Smith, Hossein Najmabadi

  International journal of pediatric otorhinolaryngology. 12/2011; 76(2):268-71.

  Hereditary hearing impairment is a genetically heterogeneous disorder. In spite of this, mutations in the GJB2 gene, encoding connexin 26 (Cx26), are a major cause of nonsyndromic recessive hearingHereditary hearing impairment is a genetically heterogeneous disorder. In spite of this, mutations in the GJB2 gene, encoding connexin 26 (Cx26), are a major cause of nonsyndromic recessive hearing loss in many countries and are largely dependent on ethnic groups. The purpose of our study was to characterize the type and prevalence of GJB2 mutations among Azeri population of Iran. Fifty families presenting autosomal recessive nonsyndromic hearing loss from Ardabil province of Iran were studied for mutations in GJB2 gene. All DNA samples were screened for c.35delG mutation by ARMS PCR. Samples from patients who were normal for c.35delG were analyzed for the other variations in GJB2 by direct sequencing. In the absence of mutation detection, GJB6 was screened for the del(GJB6-D13S1830) and del(GJB6-D13S1854). Thirteen families demonstrated alteration in the Cx26 (26%). The 35delG mutation was the most common one, accounting for 69.2% (9 out of 13 families). All the detected families were homozygous for this mutation. Two families were homozygous for delE120 and 299-300delAT mutations. We also identified a novel mutation: c.463-464 delTA in 2 families resulting in a frame shift mutation. Our results suggest that c.35delG mutation in the GJB2 gene is the most important cause of GJB2 related deafness in Iranian Azeri population.

• Deep sequencing reveals 50 novel genes for recessive cognitive disorders.

  Authors: Hossein Najmabadi, Hao Hu, Masoud Garshasbi, Tomasz Zemojtel, Seyedeh Sedigheh Abedini, Wei Chen, Masoumeh Hosseini, Farkhondeh Behjati, Stefan Haas, Payman Jamali [......] Mohammad Javad Soltani Banavandi, Julia Hoffer, Masoumeh Falah, Luciana Musante, Vera Kalscheuer, Reinhard Ullmann, Andreas Walter Kuss, Andreas Tzschach, Kimia Kahrizi, H Hilger Ropers

  Nature. 09/2011; 478(7367):57-63.

  Common diseases are often complex because they are genetically heterogeneous, with many different genetic defects giving rise to clinically indistinguishable phenotypes. This has been amplyCommon diseases are often complex because they are genetically heterogeneous, with many different genetic defects giving rise to clinically indistinguishable phenotypes. This has been amply documented for early-onset cognitive impairment, or intellectual disability, one of the most complex disorders known and a very important health care problem worldwide. More than 90 different gene defects have been identified for X-chromosome-linked intellectual disability alone, but research into the more frequent autosomal forms of intellectual disability is still in its infancy. To expedite the molecular elucidation of autosomal-recessive intellectual disability, we have now performed homozygosity mapping, exon enrichment and next-generation sequencing in 136 consanguineous families with autosomal-recessive intellectual disability from Iran and elsewhere. This study, the largest published so far, has revealed additional mutations in 23 genes previously implicated in intellectual disability or related neurological disorders, as well as single, probably disease-causing variants in 50 novel candidate genes. Proteins encoded by several of these genes interact directly with products of known intellectual disability genes, and many are involved in fundamental cellular processes such as transcription and translation, cell-cycle control, energy metabolism and fatty-acid synthesis, which seem to be pivotal for normal brain development and function.

• ST3GAL3 mutations impair the development of higher cognitive functions.

  Authors: Hao Hu, Katinka Eggers, Wei Chen, Masoud Garshasbi, M Mahdi Motazacker, Klaus Wrogemann, Kimia Kahrizi, Andreas Tzschach, Masoumeh Hosseini, Ideh Bahman, Tim Hucho, Martina Mühlenhoff, Rita Gerardy-Schahn, Hossein Najmabadi, H Hilger Ropers, Andreas W Kuss

  American journal of human genetics. 09/2011; 89(3):407-14.

  The genetic variants leading to impairment of intellectual performance are highly diverse and are still poorly understood. ST3GAL3 encodes the Golgi enzyme β-galactoside-α2,3-sialyltransferase-IIIThe genetic variants leading to impairment of intellectual performance are highly diverse and are still poorly understood. ST3GAL3 encodes the Golgi enzyme β-galactoside-α2,3-sialyltransferase-III that in humans predominantly forms the sialyl Lewis a epitope on proteins. ST3GAL3 resides on chromosome 1 within the MRT4 locus previously identified to associate with nonsyndromic autosomal recessive intellectual disability. We searched for the disease-causing mutations in the MRT4 family and a second independent consanguineous Iranian family by using a combination of chromosome sorting and next-generation sequencing. Two different missense changes in ST3GAL3 cosegregate with the disease but were absent in more than 1000 control chromosomes. In cellular and biochemical test systems, these mutations were shown to cause ER retention of the Golgi enzyme and drastically impair ST3Gal-III functionality. Our data provide conclusive evidence that glycotopes formed by ST3Gal-III are prerequisite for attaining and/or maintaining higher cognitive functions.

• Did the GJB2 35delG mutation originate in Iran?

  Authors: Vahideh Norouzi, Hiva Azizi, Zohreh Fattahi, Fatemehsadat Esteghamat, Niloofar Bazazzadegan, Carla Nishimura, Nooshin Nikzat, Khadijeh Jalalvand, Kimia Kahrizi, Richard J H Smith, Hossein Najmabadi

  American journal of medical genetics. Part A. 09/2011; 155A(10):2453-8.

  Mutations in GJB2 are a major cause of autosomal recessive non-syndromic hearing loss (ARNSHL) in many populations. A single mutation of this gene (35delG) accounts for approximately 70% of GJB2Mutations in GJB2 are a major cause of autosomal recessive non-syndromic hearing loss (ARNSHL) in many populations. A single mutation of this gene (35delG) accounts for approximately 70% of GJB2 mutations that are associated with ARNSHL in Caucasians in many European countries and also in Iranian. In this study, we used PCR and restriction digestion to genotype five single nucleotide polymorphisms (SNPs) that define the genetic background of the 35delG mutation over an interval of 98 Kbp that includes the coding and flanking regions of GJB2. Two microsatellite markers, D13S175 and D13S141, were also analyzed in patients and controls. These data suggest that the 35delG mutation originated in northern Iran.

• A novel nonsense mutation in TUSC3 is responsible for non-syndromic autosomal recessive mental retardation in a consanguineous Iranian family.

  Authors: Masoud Garshasbi, Kimia Kahrizi, Masoumeh Hosseini, Leila Nouri Vahid, Masoumeh Falah, Sahel Hemmati, Hao Hu, Andreas Tzschach, Hans Hilger Ropers, Hossein Najmabadi, Andreas Walter Kuss

  American journal of medical genetics. Part A. 08/2011; 155A(8):1976-80.

  The genetic basis of autosomal recessive mental retardation (ARMR) is extremely heterogeneous, and there is reason to suspect that the number of underlying gene defects may well go beyond 1,000. ToThe genetic basis of autosomal recessive mental retardation (ARMR) is extremely heterogeneous, and there is reason to suspect that the number of underlying gene defects may well go beyond 1,000. To date, however, only less than 10 genes have been implicated in non-specific/non-syndromic ARMR (NS-ARMR). As part of an ongoing systematic study aiming to identify further ARMR genes, we investigated a consanguineous family with three patients with NS-ARMR. By linkage analysis and subsequent mutation screening we identified a novel nonsense mutation (c.163C > T [p.Q55X]) in the second exon of the TUSC3 gene. This is the third MR causing defect in TUSC3 to be described and the second independent mutation in this gene in a cohort of more than 200 ARMR families from the Iranian population. This argues for a more prominent role of TUSC3 in the etiology of this genetically heterogeneous disorder as compared to most of the other so far identified ARMR genes.

• Mutation of the conserved polyadenosine RNA binding protein, ZC3H14/dNab2, impairs neural function in Drosophila and humans.

  Authors: Changhui Pak, Masoud Garshasbi, Kimia Kahrizi, Christina Gross, Luciano H Apponi, John J Noto, Seth M Kelly, Sara W Leung, Andreas Tzschach, Farkhondeh Behjati [......] Kathryn R Williams, Sharon Burdick, Yue Feng, Subhabrata Sanyal, Gary J Bassell, Hans-Hilger Ropers, Hossein Najmabadi, Anita H Corbett, Kenneth H Moberg, Andreas W Kuss

  Proceedings of the National Academy of Sciences of the United States of America. 07/2011; 108(30):12390-5.

  Here we report a human intellectual disability disease locus on chromosome 14q31.3 corresponding to mutation of the ZC3H14 gene that encodes a conserved polyadenosine RNA binding protein. We identifyHere we report a human intellectual disability disease locus on chromosome 14q31.3 corresponding to mutation of the ZC3H14 gene that encodes a conserved polyadenosine RNA binding protein. We identify ZC3H14 mRNA transcripts in the human central nervous system, and we find that rodent ZC3H14 protein is expressed in hippocampal neurons and colocalizes with poly(A) RNA in neuronal cell bodies. A Drosophila melanogaster model of this disease created by mutation of the gene encoding the ZC3H14 ortholog dNab2, which also binds polyadenosine RNA, reveals that dNab2 is essential for development and required in neurons for normal locomotion and flight. Biochemical and genetic data indicate that dNab2 restricts bulk poly(A) tail length in vivo, suggesting that this function may underlie its role in development and disease. These studies reveal a conserved requirement for ZC3H14/dNab2 in the metazoan nervous system and identify a poly(A) RNA binding protein associated with a human brain disorder.

• Mutations in the alpha 1,2-mannosidase gene, MAN1B1, cause autosomal-recessive intellectual disability.

  Authors: Muhammad Arshad Rafiq, Andreas W Kuss, Lucia Puettmann, Abdul Noor, Annapoorani Ramiah, Ghazanfar Ali, Hao Hu, Nadir Ali Kerio, Yong Xiang, Masoud Garshasbi [......] Andreas Tzschach, Kimia Kahrizi, Khalid Mahmood, Farooq Naeem, Muhammad Ayub, Kelley W Moremen, John B Vincent, Hans Hilger Ropers, Muhammad Ansar, Hossein Najmabadi

  American journal of human genetics. 07/2011; 89(1):176-82.

  We have used genome-wide genotyping to identify an overlapping homozygosity-by-descent locus on chromosome 9q34.3 (MRT15) in four consanguineous families affected by nonsyndromic autosomal-recessiveWe have used genome-wide genotyping to identify an overlapping homozygosity-by-descent locus on chromosome 9q34.3 (MRT15) in four consanguineous families affected by nonsyndromic autosomal-recessive intellectual disability (NS-ARID) and one in which the patients show additional clinical features. Four of the families are from Pakistan, and one is from Iran. Using a combination of next-generation sequencing and Sanger sequencing, we have identified mutations in the gene MAN1B1, encoding a mannosyl oligosaccharide, alpha 1,2-mannosidase. In one Pakistani family, MR43, a homozygous nonsense mutation (RefSeq number NM_016219.3: c.1418G>A [p.Trp473*]), segregated with intellectual disability and additional dysmorphic features. We also identified the missense mutation c. 1189G>A (p.Glu397Lys; RefSeq number NM_016219.3), which segregates with NS-ARID in three families who come from the same village and probably have shared inheritance. In the Iranian family, the missense mutation c.1000C>T (p.Arg334Cys; RefSeq number NM_016219.3) also segregates with NS-ARID. Both missense mutations are at amino acid residues that are conserved across the animal kingdom, and they either reduce k(cat) by ∼1300-fold or disrupt stable protein expression in mammalian cells. MAN1B1 is one of the few NS-ARID genes with an elevated mutation frequency in patients with NS-ARID from different populations.

• Two Iranian families with a novel mutation in GJB2 causing autosomal dominant nonsyndromic hearing loss.

  Authors: Niloofar Bazazzadegan, Abraham M Sheffield, Masoomeh Sobhani, Kimia Kahrizi, Nicole C Meyer, Guy Van Camp, Nele Hilgert, Seyedeh Sedigheh Abedini, Farkhondeh Habibi, Ahmad Daneshi, Carla Nishimura, Matthew R Avenarius, Mohammad Farhadi, Richard J H Smith, Hossein Najmabadi

  American journal of medical genetics. Part A. 05/2011; 155A(5):1202-11.

  Mutations in GJB2, encoding connexin 26 (Cx26), cause both autosomal dominant and autosomal recessive nonsyndromic hearing loss (ARNSHL) at the DFNA3 and DFNB1 loci, respectively. Most of the overMutations in GJB2, encoding connexin 26 (Cx26), cause both autosomal dominant and autosomal recessive nonsyndromic hearing loss (ARNSHL) at the DFNA3 and DFNB1 loci, respectively. Most of the over 100 described GJB2 mutations cause ARNSHL. Only a minority has been associated with autosomal dominant hearing loss. In this study, we present two families with autosomal dominant nonsyndromic hearing loss caused by a novel mutation in GJB2 (p.Asp46Asn). Both families were ascertained from the same village in northern Iran consistent with a founder effect. This finding implicates the D46N missense mutation in Cx26 as a common cause of deafness in this part of Iran mandating mutation screening of GJB2 for D46N in all persons with hearing loss who originate from this geographic region.

• Chromosome abnormality rate among Iranian patients with idiopathic mental retardation from consanguineous marriages.

  Authors: Farkhondeh Behjati, Saghar Ghasemi Firouzabadi, Kimia Kahrizi, Roxana Kariminejad, Iman Bagherizadeh, Javad Ansari, Masoumeh Fallah, Forough Mojtahedi, Hossein Darvish, Gholamreza Bahrami Monajemi, S Sedigheh Abedini, Payman Jamali, Faezeh Mojahedi, Azita Zadeh-Vakili, Hossein Najmabadi

  Archives of medical science : AMS. 04/2011; 7(2):321-5.

  Mental retardation (MR) has heterogeneous aetiology mostly with genetic causes. Chromosomal aberrations are one of the most common causes of MR. Reports on chromosome abnormality rate amongMental retardation (MR) has heterogeneous aetiology mostly with genetic causes. Chromosomal aberrations are one of the most common causes of MR. Reports on chromosome abnormality rate among consanguineous families are sparse. In order to identify the chromosome abnormality rate in idiopathic mental retardation from consanguineous marriages, a total of 322 Iranian families with positive family history for MR were investigated in the Genetics Research Center. In the majority of families (92%) at least two sibs were affected with MR and none had specific chromosomal syndromes such as Down syndrome. Standard cytogenetic techniques using high resolution GTG banding were carried out on all the patients. The overall chromosome abnormality rate contributing to mental retardation was 1.24% (4 cases), which comprised 46,XY,der(18)t(4;18)(q31.1;q23)mat; 45,XY,-21,-22,+der(22)t(21;22)(q21.1;q13.33)mat; 46,XY,rec(2)dup(2p)inv(2)(p25.1q37.3)pat, and 46,XY,der(11)t(10;11)(q25.2;q25)pat. Although the most likely genetic cause of mental retardation in patients with consanguineous parents is autosomal recessive, the fact that 1.24% of our patients had chromosomal abnormalities emphasizes the importance of cytogenetic investigation as the first laboratory genetic tests for all MR patients. To our knowledge, this is the first report on the rate of chromosome abnormality among patients with idiopathic mental retardation from consanguineous marriages.

• Loss-of-function mutations of ILDR1 cause autosomal-recessive hearing impairment DFNB42.

  Authors: Guntram Borck, Atteeq Ur Rehman, Kwanghyuk Lee, Hans-Martin Pogoda, Naseebullah Kakar, Simon von Ameln, Nicolas Grillet, Michael S Hildebrand, Zubair M Ahmed, Gudrun Nürnberg [......] Saima Riazuddin, Richard J H Smith, Wasim Ahmad, Ulrich Müller, Matthias Hammerschmidt, Thomas B Friedman, Sheikh Riazuddin, Suzanne M Leal, Jamil Ahmad, Christian Kubisch

  American journal of human genetics. 02/2011; 88(2):127-37.

  By using homozygosity mapping in a consanguineous Pakistani family, we detected linkage of nonsyndromic hearing loss to a 7.6 Mb region on chromosome 3q13.31-q21.1 within the previously reportedBy using homozygosity mapping in a consanguineous Pakistani family, we detected linkage of nonsyndromic hearing loss to a 7.6 Mb region on chromosome 3q13.31-q21.1 within the previously reported DFNB42 locus. Subsequent candidate gene sequencing identified a homozygous nonsense mutation (c.1135G>T [p.Glu379X]) in ILDR1 as the cause of hearing impairment. By analyzing additional consanguineous families with homozygosity at this locus, we detected ILDR1 mutations in the affected individuals of 10 more families from Pakistan and Iran. The identified ILDR1 variants include missense, nonsense, frameshift, and splice-site mutations as well as a start codon mutation in the family that originally defined the DFNB42 locus. ILDR1 encodes the evolutionarily conserved immunoglobulin-like domain containing receptor 1, a putative transmembrane receptor of unknown function. In situ hybridization detected expression of Ildr1, the murine ortholog, early in development in the vestibule and in hair cells and supporting cells of the cochlea. Expression in hair cell- and supporting cell-containing neurosensory organs is conserved in the zebrafish, in which the ildr1 ortholog is prominently expressed in the developing ear and neuromasts of the lateral line. These data identify loss-of-function mutations of ILDR1, a gene with a conserved expression pattern pointing to a conserved function in hearing in vertebrates, as underlying nonsyndromic prelingual sensorineural hearing impairment.

• Next generation sequencing in a family with autosomal recessive Kahrizi syndrome (OMIM 612713) reveals a homozygous frameshift mutation in SRD5A3.

  Authors: Kimia Kahrizi, Cougar Hao Hu, Masoud Garshasbi, Seyedeh Sedigheh Abedini, Shirin Ghadami, Roxana Kariminejad, Reinhard Ullmann, Wei Chen, H-Hilger Ropers, Andreas W Kuss, Hossein Najmabadi, Andreas Tzschach

  European journal of human genetics : EJHG. 01/2011; 19(1):115-7.

  As part of a large-scale, systematic effort to unravel the molecular causes of autosomal recessive mental retardation, we have previously described a novel syndrome consisting of mental retardation,As part of a large-scale, systematic effort to unravel the molecular causes of autosomal recessive mental retardation, we have previously described a novel syndrome consisting of mental retardation, coloboma, cataract and kyphosis (Kahrizi syndrome, OMIM 612713) and mapped the underlying gene to a 10.4-Mb interval near the centromere on chromosome 4. By combining array-based exon enrichment and next generation sequencing, we have now identified a homozygous frameshift mutation (c.203dupC; p.Phe69LeufsX2) in the gene for steroid 5α-reductase type 3 (SRD5A3) as the disease-causing change in this interval. Recent evidence indicates that this enzyme is required for the conversion of polyprenol to dolichol, a step that is essential for N-linked protein glycosylation. Independently, another group has recently observed SRD5A3 mutations in several families with a type 1 congenital disorder of glycosylation (CDG type Ix, OMIM 212067), mental retardation, cerebellar ataxia and eye disorders. Our results show that Kahrizi syndrome and this CDG Ix subtype are allelic disorders, and they illustrate the potential of next-generation sequencing strategies for the elucidation of single gene defects.

• Mutations in TMC1 are a common cause of DFNB7/11 hearing loss in the Iranian population.

  Authors: Michael S Hildebrand, Kimia Kahrizi, Catherine J Bromhead, A Eliot Shearer, Jennifer A Webster, Hossein Khodaei, Rezvan Abtahi, Niloofar Bazazzadegan, Mojgan Babanejad, Nooshin Nikzat, William J Kimberling, Dietrich Stephan, Patrick L M Huygen, Melanie Bahlo, Richard J H Smith, Hossein Najmabadi

  The Annals of otology, rhinology, and laryngology. 12/2010; 119(12):830-5.

  We investigated the cause of autosomal recessive nonsyndromic hearing loss (ARNSHL) that segregated in 2 consanguineous Iranian families. Otologic and audiometric examinations were performed onWe investigated the cause of autosomal recessive nonsyndromic hearing loss (ARNSHL) that segregated in 2 consanguineous Iranian families. Otologic and audiometric examinations were performed on affected members of each family. Genome-wide parametric multipoint linkage mapping using a recessive model was performed with Affymetrix 50K GeneChips or short tandem repeat polymorphisms. Direct sequencing was used to confirm the causative mutation in each family. In 2 Iranian families, L-1651 and L-8600606, with ARNSHL that mapped to the DFNB7/11 locus, homozygosity for a reported splice site mutation (c.776+1G>A), and a novel deletion (c.1589_1590delCT; p.S530*) were identified in the TMC1 gene, respectively. Consistent with the previously reported phenotype in DFNB7/11 families, the 2 Iranian families had segregated congenital, profound hearing impairment. However, in family L-1651, one affected family member (IV:3) has milder hearing impairment than expected, suggesting a potential genetic modifier effect. These results indicate that DFNB7/11 is a common form of genetic hearing loss in Iran, because this population is the source of 6 of the 29 TMC1 mutations reported worldwide.

• Brachyphalangy, polydactyly and tibial aplasia/hypoplasia syndrome (OMIM 609945): case report and review of the literature.

  Authors: Yousef Shafeghati, Kimia Kahrizi, Hossein Najmabadi, Andreas Walter Kuss, Hans-Hilger Ropers, Andreas Tzschach

  European journal of pediatrics. 12/2010; 169(12):1535-9.

  Brachyphalangy, polydactyly and tibial aplasia/hypoplasia syndrome (OMIM 609945) is a rare congenital disorder. Only seven patients have been reported to date, and the etiology of this syndrome isBrachyphalangy, polydactyly and tibial aplasia/hypoplasia syndrome (OMIM 609945) is a rare congenital disorder. Only seven patients have been reported to date, and the etiology of this syndrome is unknown. Autosomal dominant inheritance with variable expression has been suggested based on the presence of minor features in some parents and the fact that neither parental consanguinity nor pairs of affected siblings were observed. We report on the first patient with this syndrome who was born to consanguineous parents. Neither the mother nor the father, who were first cousins, had clinical features suggestive of a manifestation of brachyphalangy, polydactyly and tibial aplasia/hypoplasia syndrome. The patient had no siblings, and the family history was unremarkable. Clinical problems included brachydactyly of hands and feet, splaying of fingers and toes, preaxial polydactyly of feet, bilateral tibial aplasia, shortened radius and ulna, and characteristic facial dysmorphic signs. The detailed description of this patient adds to our knowledge of the clinical manifestations of brachyphalangy, polydactyly and tibial aplasia/hypoplasia syndrome and will eventually also contribute to the elucidation of the underlying gene defects.

• Genetic male infertility and mutation of CATSPER ion channels.

  Authors: Michael S Hildebrand, Matthew R Avenarius, Marc Fellous, Yuzhou Zhang, Nicole C Meyer, Jana Auer, Catherine Serres, Kimia Kahrizi, Hossein Najmabadi, Jacques S Beckmann, Richard J H Smith

  European journal of human genetics : EJHG. 11/2010; 18(11):1178-84.

  A clinically significant proportion of couples experience difficulty in conceiving a child. In about half of these cases male infertility is the cause and often genetic factors are involved. DespiteA clinically significant proportion of couples experience difficulty in conceiving a child. In about half of these cases male infertility is the cause and often genetic factors are involved. Despite advances in clinical diagnostics ∼50% of male infertility cases remain idiopathic. Based on this, further analysis of infertile males is required to identify new genetic factors involved in male infertility. This review focuses on cation channel of sperm (CATSPER)-related male infertility. It is based on PubMed literature searches using the keywords 'CATSPER', 'male infertility', 'male contraception', 'immunocontraception' and 'pharmacologic contraception' (publication dates from January 1979 to December 2009). Previously, contiguous gene deletions including the CATSPER2 gene implicated the sperm-specific CATSPER channel in syndromic male infertility (SMI). Recently, we identified insertion mutations of the CATSPER1 gene in families with recessively inherited nonsyndromic male infertility (NSMI). The CATSPER channel therefore represents a novel human male fertility factor. In this review we summarize the genetic and clinical data showing the role of CATSPER mutation in human forms of NSMI and SMI. In addition, we discuss clinical management and therapeutic options for these patients. Finally, we describe how the CATSPER channel could be used as a target for development of a male contraceptive.

• Autosomal recessive mental retardation: homozygosity mapping identifies 27 single linkage intervals, at least 14 novel loci and several mutation hotspots.

  Authors: Andreas Walter Kuss, Masoud Garshasbi, Kimia Kahrizi, Andreas Tzschach, Farkhondeh Behjati, Hossein Darvish, Lia Abbasi-Moheb, Lucia Puettmann, Agnes Zecha, Robert Weissmann [......] Valeh Hadavi, Gholamreza Bahrami-Monajemi, Mahboubeh Kasiri, Masoumeh Falah, Pooneh Nikuei, Atefeh Dehghan, Masoumeh Sobhani, Payman Jamali, Hans Hilger Ropers, Hossein Najmabadi

  Human genetics. 11/2010; 129(2):141-8.

  Mental retardation (MR) has a worldwide prevalence of around 2% and is a frequent cause of severe disability. Significant excess of MR in the progeny of consanguineous matings as well as functionalMental retardation (MR) has a worldwide prevalence of around 2% and is a frequent cause of severe disability. Significant excess of MR in the progeny of consanguineous matings as well as functional considerations suggest that autosomal recessive forms of MR (ARMR) must be relatively common. To shed more light on the causes of autosomal recessive MR (ARMR), we have set out in 2003 to perform systematic clinical studies and autozygosity mapping in large consanguineous Iranian families with non-syndromic ARMR (NS-ARMR). As previously reported (Najmabadi et al. in Hum Genet 121:43-48, 2007), this led us to the identification of 12 novel ARMR loci, 8 of which had a significant LOD score (OMIM: MRT5-12). In the meantime, we and others have found causative gene defects in two of these intervals. Moreover, as reported here, tripling the size of our cohort has enabled us to identify 27 additional unrelated families with NS-ARMR and single-linkage intervals; 14 of these define novel loci for non-syndromic ARMR. Altogether, 13 out of 39 single linkage intervals observed in our cohort were found to cluster at 6 different loci on chromosomes, i.e., 1p34, 4q27, 5p15, 9q34, 11p11-q13 and 19q13, respectively. Five of these clusters consist of two significantly overlapping linkage intervals, and on chr 1p34, three single linkage intervals coincide, including the previously described MRT12 locus. The probability for this distribution to be due to chance is only 1.14 × 10(-5), as shown by Monte Carlo simulation. Thus, in contrast to our previous conclusions, these novel data indicate that common molecular causes of NS-ARMR do exist, and in the Iranian population, the most frequent ones may well account for several percent of the patients. These findings will be instrumental in the identification of the underlying genes.

• miRNA mutations are not a common cause of deafness.

  Authors: Michael S Hildebrand, P Dane Witmer, Shunbin Xu, Stephen S Newton, Kimia Kahrizi, Hossein Najmabadi, David Valle, Richard J H Smith

  American journal of medical genetics. Part A. 02/2010; 152A(3):646-52.

  Mutations in miRNA genes have been implicated in hearing loss in human families and mice. It is also possible that mutations in miRNA binding sites of inner ear targets alter gene expression levelsMutations in miRNA genes have been implicated in hearing loss in human families and mice. It is also possible that mutations in miRNA binding sites of inner ear targets alter gene expression levels and lead to hearing loss. To investigate these possibilities we screened predicted target genes of the miR-183 miRNA cluster known to be expressed in the inner ear sensory epithelium. In one Iranian family segregating autosomal recessive non-syndromic hearing loss (ARNSHL), we identified a homozygous variant in a predicted miR-96/182 binding site in the 3'UTR of the RDX (DFNB24) gene. However, in vitro functional studies showed that this site is not a functional target for miR-96/182. We extended our study to include the miR-183 genes themselves and 24 additional predicted target genes of the miRNA-183 cluster. Screening these miRNAs and target sequences in numerous families segregating either autosomal dominant non-syndromic deafness (ADNSHL) or ARNSHL did not identify any potential deafness-causing mutations. These results suggest that mutations disrupting gene regulation by the miR-183 cluster are not a common cause of human hearing loss.

• Identification of mutations in TRAPPC9, which encodes the NIK- and IKK-beta-binding protein, in nonsyndromic autosomal-recessive mental retardation.

  Authors: Asif Mir, Liana Kaufman, Abdul Noor, Mahdi M. Motazacker, Talal Jamil, Matloob Azam, Kimia Kahrizi, Muhammad Arshad Rafiq, Rosanna Weksberg, Tanveer Nasr, Farooq Naeem, Andreas Tzschach, Andreas W Kuss, Gisele E. Ishak, Dan Doherty, H Hilger Ropers, A. James Barkovich, Hossein Najmabadi, Muhammad Ayub, John B Vincent

  American journal of human genetics. 12/2009; 85(6):909-15.

  Mental retardation/intellectual disability is a devastating neurodevelopmental disorder with serious impact on affected individuals and their families, as well as on health and social services. ItMental retardation/intellectual disability is a devastating neurodevelopmental disorder with serious impact on affected individuals and their families, as well as on health and social services. It occurs with a prevalence of approximately 2%, is an etiologically heterogeneous condition, and is frequently the result of genetic aberrations. Autosomal-recessive forms of nonsyndromic MR (NS-ARMR) are believed to be common, yet only five genes have been identified. We have used homozygosity mapping to search for the gene responsible for NS-ARMR in a large Pakistani pedigree. Using Affymetrix 5.0 single nucleotide polymorphism (SNP) microarrays, we identified a 3.2 Mb region on 8q24 with a continuous run of 606 homozygous SNPs shared among all affected members of the family. Additional genotype data from microsatellite markers verified this, allowing us to calculate a two-point LOD score of 5.18. Within this region, we identified a truncating homozygous mutation, R475X, in exon 7 of the gene TRAPPC9. In a second large NS-ARMR/ID family, previously linked to 8q24 in a study of Iranian families, we identified a 4 bp deletion within exon 14 of TRAPPC9, also segregating with the phenotype and truncating the protein. This gene encodes NIK- and IKK-beta-binding protein (NIBP), which is involved in the NF-kappaB signaling pathway and directly interacts with IKK-beta and MAP3K14. Brain magnetic resonance imaging of affected individuals indicates the presence of mild cerebral white matter hypoplasia. Microcephaly is present in some but not all affected individuals. Thus, to our knowledge, this is the sixth gene for NS-ARMR to be discovered.

• Mutations in LOXHD1, an evolutionarily conserved stereociliary protein, disrupt hair cell function in mice and cause progressive hearing loss in humans.

  Authors: Nicolas Grillet, Martin Schwander, Michael S Hildebrand, Anna Sczaniecka, Anand Kolatkar, Janice Velasco, Jennifer A Webster, Kimia Kahrizi, Hossein Najmabadi, William J Kimberling, Dietrich Stephan, Melanie Bahlo, Tim Wiltshire, Lisa M Tarantino, Peter Kuhn, Richard J H Smith, Ulrich Müller

  American journal of human genetics. 10/2009; 85(3):328-37.

  Hearing loss is the most common form of sensory impairment in humans and is frequently progressive in nature. Here we link a previously uncharacterized gene to hearing impairment in mice and humans.Hearing loss is the most common form of sensory impairment in humans and is frequently progressive in nature. Here we link a previously uncharacterized gene to hearing impairment in mice and humans. We show that hearing loss in the ethylnitrosourea (ENU)-induced samba mouse line is caused by a mutation in Loxhd1. LOXHD1 consists entirely of PLAT (polycystin/lipoxygenase/alpha-toxin) domains and is expressed along the membrane of mature hair cell stereocilia. Stereociliary development is unaffected in samba mice, but hair cell function is perturbed and hair cells eventually degenerate. Based on the studies in mice, we screened DNA from human families segregating deafness and identified a mutation in LOXHD1, which causes DFNB77, a progressive form of autosomal-recessive nonsyndromic hearing loss (ARNSHL). LOXHD1, MYO3a, and PJVK are the only human genes to date linked to progressive ARNSHL. These three genes are required for hair cell function, suggesting that age-dependent hair cell failure is a common mechanism for progressive ARNSHL.

• Human Male Infertility Caused by Mutations in the CATSPER1 Channel Protein.

  Authors: Matthew R Avenarius, Michael S Hildebrand, Yuzhou Zhang, Nicole C Meyer, Luke L H Smith, Kimia Kahrizi, Hossein Najmabadi, Richard J H Smith

  American journal of human genetics. 05/2009;

  Male infertility, a common barrier that prevents successful conception, is a reproductive difficulty affecting 15% of couples. Heritable forms of nonsyndromic male infertility can arise fromMale infertility, a common barrier that prevents successful conception, is a reproductive difficulty affecting 15% of couples. Heritable forms of nonsyndromic male infertility can arise from single-gene defects as well as chromosomal abnormalities. Although no CATSPER gene has been identified as causative for human male infertility, male mice deficient for members of the CatSper gene family are infertile. In this study, we used routine semen analysis to identify two consanguineous Iranian families segregating autosomal-recessive male infertility. Autozygosity by descent was demonstrated in both families for a approximately 11 cM region on chromosome 11q13.1, flanked by markers D11S1765 and D11S4139. This region contains the human CATSPER1 gene. Denaturing high-performance liquid chromatography (DHPLC) and bidirectional sequence analysis of CATSPER1 in affected family members revealed two separate insertion mutations (c.539-540insT and c.948-949insATGGC) that are predicted to lead to frameshifts and premature stop codons (p.Lys180LysfsX8 and p.Asp317MetfsX18). CATSPER1 is one of four members of the sperm-specific CATSPER voltage-gated calcium channel family known to be essential for normal male fertility in mice. These results suggest that CATSPER1 is also essential for normal male fertility in humans.