[Show abstract][Hide abstract] ABSTRACT: Neurofibromatosis type 1 (NF1) is one of the most frequent genetic disorders, affecting 1:3000 worldwide. Identification of genotype-phenotype correlations is challenging due to the wide range clinical variability, the progressive nature of the disorder and extreme diversity of the mutational spectrum. We report 136 individuals with a distinct phenotype carrying one of 5 different NF1 missense mutations affecting p.Arg1809. Patients presented with multiple café-au-lait macules (CALM) with or without freckling and Lisch nodules, but no externally visible plexiform neurofibromas or clear cutaneous neurofibromas were found. About 25% of the individuals had Noonan-like features. Pulmonic stenosis and short stature were significantly more prevalent compared to classic cohorts (p<0.0001). Developmental delays and/or learning disabilities were reported in over 50% of patients. Melanocytes cultured from a CALM in a segmental NF1-patient showed two different somatic NF1 mutations, p.Arg1809Cys and a multi-exon deletion, providing genetic evidence that p.Arg1809Cys is a loss-of-function mutation in the melanocytes and causes a pigmentary phenotype. Constitutional missense mutations at p.Arg1809 affect 1.23% of unrelated NF1 probands in the UAB cohort, therefore this specific NF1 genotype-phenotype correlation will affect counseling and management of a significant number of patients. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
Human Mutation 07/2015; 36(11). DOI:10.1002/humu.22832 · 5.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fragile X syndrome is the most common inherited form of intellectual disability. Here we report on a study based on a collaborative registry, involving 12 Spanish centres, of molecular diagnostic tests in 1105 fragile X families comprising 5062 individuals, of whom, 1655 carried a full mutation or were mosaic, three cases had deletions, 1840 had a premutation, and 102 had intermediate alleles. Two patients with the full mutation also had Klinefelter syndrome. We have used this registry to assess the risk of expansion from parents to children. From mothers with premutation, the overall rate of allele expansion to full mutation is 52.5%, and we found that this rate is higher for male than female offspring (63.6% versus 45.6%; P < 0.001). Furthermore, in mothers with intermediate alleles (45-54 repeats), there were 10 cases of expansion to a premutation allele, and for the smallest premutation alleles (55-59 repeats), there was a 6.4% risk of expansion to a full mutation, with 56 repeats being the smallest allele that expanded to a full mutation allele in a single meiosis. Hence, in our series the risk for alleles of <59 repeats is somewhat higher than in other published series. These findings are important for genetic counselling.
[Show abstract][Hide abstract] ABSTRACT: Fragile X syndrome is themost common inherited formof intellectual disability. Here we report on a study based on a collaborative registry, involving 12 Spanish centres, ofmolecular diagnostic tests in 1105 fragile X families comprising 5062 individuals, of whom,1655 carried a fullmutation or were mosaic, three cases had deletions, 1840 had a premutation, and 102 had intermediate alleles. Two patients with the fullmutation also had Klinefelter syndrome.We have used this registry to assess the risk of expansion from parents to children. From mothers with premutation, the overall rate of allele expansion to full mutation is 52.5%, and we found that this rate is higher for male than female offspring (63.6% versus 45.6%; 𝑃 < 0.001). Furthermore, in mothers with intermediate alleles(45–54 repeats), there were 10 cases of expansion to a premutation allele, and for the smallest premutation alleles (55–59 repeats),there was a 6.4% risk of expansion to a fullmutation, with 56 repeats being the smallest allele that expanded to a fullmutation allelein a single meiosis. Hence, in our series the risk for alleles of <59 repeats is somewhat higher than in other published series. Thesefindings are important for genetic counselling.
BioMed Research International 05/2014; Article ID 195793,:8 pages. · 2.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Patients affected by chronic lymphocytic leukemia (CLL) have an increased risk of developing a second cancer. There is not a definitive explanation for this phenomenon, although some hypotheses have been postulated. The aim of the present work was to assess the presence of second cancer in untreated patients with CLL who were cytogenetically characterized, and secondly to investigate if there is a correlation between the genetics of CLL and the emergence of second cancer.
We performed conventional cytogenetics and Fluorescent in situ hybridization analyses in a series of 106 patients.
We observed that nearly 8% of cases developed second cancer, mostly epithelial tumors. The majority of them presented two common features, del(13)(q14.3) and the presence of at least two genetic alterations.
We suggest that the genetic background of CLL, particularly the presence of several genetic alterations, influences the emergence of second cancer in patients affected by CLL.
Anticancer research 05/2014; 34(5):2311-4. · 1.83 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background
Congenital heart defects (CHD) is the most common cause of death from a congenital structure abnormality in newborns and is often associated with fetal loss. There are many types of CHD. Human genetic studies have identified genes that are responsible for the inheritance of a particular type of CHD and for some types of CHD previously thought to be sporadic. However, occasionally different members of the same family might have anatomically distinct defects — for instance, one member with atrial septal defect, one with tetralogy of Fallot, and one with ventricular septal defect. Our objective is to identify susceptibility loci for CHD in families affected by distinct defects. The occurrence of these apparently discordant clinical phenotypes within one family might hint at a genetic framework common to most types of CHD.
We performed a genome-wide linkage analysis using MOD score analysis in families with diverse CHD. Significant linkage was obtained in two regions, at chromosome 15 (15q26.3, Pempirical = 0.0004) and at chromosome 18 (18q21.2, Pempirical = 0.0005).
In these two novel regions four candidate genes are located: SELS, SNRPA1, and PCSK6 on 15q26.3, and TCF4 on 18q21.2. The new loci reported here have not previously been described in connection with CHD. Although further studies in other cohorts are needed to confirm these findings, the results presented here together with recent insight into how the heart normally develops will improve the understanding of CHD.
[Show abstract][Hide abstract] ABSTRACT: The results obtained in genetic tests are valid for the whole life. They are important, not only for the individual, but also for the family. Genetic counselling must be an integral part of the genetic testing process. An important tool that must be used in order that genetic testing is performed properly is the informed consent document. This informed consent, obtained by the physician who requests the genetic tests, is a resource to ensure that the individual voluntarily agrees and understands their purposes, as well as the consequences of the results. It emphasises the rights to receive genetic counselling, and gives the opportunity to ask questions. It also mentions the right to choose what information the subject wishes or does not wish to know.This article considers the ethical principles that justify the informed consent and its inclusion in legal regulations in order to protect fundamental human rights concerning genetic testing and genetic information, such as Spanish law 14/2007 on Biomedical Research. As conclusions, 3 models of informed consent are proposed: one for genetic testing for health reasons; an additional consent in cases where the clinical laboratory wants to store the remaining samples for future uses in biomedical research, and for clinical trials that including genetic tests.
[Show abstract][Hide abstract] ABSTRACT: To identify the genetic defect in Spanish families with Usher syndrome (USH) and probable involvement of the CLRN1 gene.
DNA samples of the affected members of our cohort of USH families were tested using an USH genotyping array, and/or genotyped with polymorphic markers specific for the USH3A locus. Based on these previous analyses and clinical findings, CLRN1 was directly sequenced in 17 patients susceptible to carrying mutations in this gene.
Microarray analysis revealed the previously reported mutation p.Y63X in two unrelated patients, one of them homozygous for the mutation. After CLRN1 sequencing, we found two novel mutations, p.R207X and p.I168N. Both novel mutations segregated with the phenotype.
To date, 18 mutations in CLRN1 have been reported. In this work, we report two novel mutations and a third one previously identified in the Spanish USH sample. The prevalence of CLRN1 among our patients with USH is low.
[Show abstract][Hide abstract] ABSTRACT: Haploinsufficiency of TBX1, encoding a T-box transcription factor, is largely responsible for the physical malformations in velo-cardio-facial /DiGeorge/22q11.2 deletion syndrome (22q11DS) patients. Cardiovascular malformations in these patients are highly variable, raising the question as to whether DNA variations in the TBX1 locus on the remaining allele of 22q11.2 could be responsible. To test this, a large sample size is needed. The TBX1 gene was sequenced in 360 consecutive 22q11DS patients. Rare and common variations were identified. We did not detect enrichment in rare SNP (single nucleotide polymorphism) number in those with or without a congenital heart defect. One exception was that there was increased number of very rare SNPs between those with normal heart anatomy compared to those with right-sided aortic arch or persistent truncus arteriosus, suggesting potentially protective roles in the SNPs for these phenotype-enrichment groups. Nine common SNPs (minor allele frequency, MAF > 0.05) were chosen and used to genotype the entire cohort of 1,022 22q11DS subjects. We did not find a correlation between common SNPs or haplotypes and cardiovascular phenotype. This work demonstrates that common DNA variations in TBX1 do not explain variable cardiovascular expression in 22q11DS patients, implicating existence of modifiers in other genes on 22q11.2 or elsewhere in the genome.
Human Mutation 07/2011; 32(11):1278-89. DOI:10.1002/humu.21568 · 5.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report the clinical and molecular characteristics of 12 Spanish families with multiple members affected with Léri-Weill dyschondrosteosis (LWD) or Langer mesomelic dysplasia (LMD), who present the SHOX (short stature homeobox gene) mutation p.A170P (c.508G>C) in heterozygosity or homozygosity, respectively. In all studied families, the A170P mutation co-segregated with the fully penetrant phenotype of mesomelic limb shortening and Madelung deformity. A shared haplotype around SHOX was observed by microsatellite analysis, confirming the presence of a common ancestor, probably of Gypsy origin, as 11 of the families were of this ethnic group. Mutation screening in 359 Eastern-European Gypsies failed to identify any carriers. For the first time, we have shown SHOX expression in the human growth plate of a 22-week LMD fetus, homozygous for the A170P mutation. Although the mutant SHOX protein was expressed in all zones of the growth plate, the chondrocyte columns in the proliferative zone were disorganized with the chondrocytes occurring in smaller columnal clusters. We have also identified a novel mutation at the same residue, c. 509C>A (p.A170D), in two unrelated Spanish LWD families, which similar to A170P mutation impedes nuclear localization of SHOX. In conclusion, we have identified A170P as the first frequent SHOX mutation in Gypsy LWD and LMD individuals.
European journal of human genetics: EJHG 06/2011; 19(12):1218-25. DOI:10.1038/ejhg.2011.128 · 4.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mutational analysis of the IDUA gene was performed in a cohort of 102 European patients with mucopolysaccharidosis type I. A total of 54 distinct mutant IDUA alleles were identified, 34 of which were novel including 12 missense mutations, 2 nonsense mutations, 12 splicing mutations, 5 micro-deletions, 1 micro-duplication 1 translational initiation site mutation, and 1 'no-stop' change (p.X654RextX62). Evidence for the pathological significance of all novel mutations identified was sought by means of a range of methodological approaches, including the assessment of evolutionary conservation, RT-PCR/in vitro splicing analysis, MutPred analysis and visual inspection of the 3D-model of the IDUA protein. Taken together, these data not only demonstrate the remarkable mutational heterogeneity characterizing type 1 mucopolysaccharidosis but also illustrate our increasing ability to make deductions pertaining to the genotype-phenotype relationship in disorders manifesting a high degree of allelic heterogeneity.
Human Mutation 06/2011; 32(6):E2189-210. DOI:10.1002/humu.21479 · 5.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hyperdiploid multiple myeloma (HMM) is being characterized by the presence of several trisomies and a low incidence of immunoglobulin heavy chain rearrangements. It has not well defined what specific steps are associated with disease progression. We present two patients that showed some primary trisomies rearranged as a step of cytogenetic and clinical progression. This prompted us to review cytogenetic results from all patients referred to our hospital to assess the importance of this phenomenon in HMM.
We carried out conventional cytogenetics in all patients. In four cases we also performed spectral karyotype (SKY) and arm-specific chromosome painting (ASP).
We demonstrate that in two patients some primary trisomies became along the disease course structurally altered and this coincided with clinical progression. We observed this phenomenon in more than 60% of HMM cases diagnosed at our laboratory.
We propose structural rearrangements of trisomies as a biological marker of progression in HMM.
Anticancer research 05/2011; 31(5):1599-602. · 1.83 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Léri-Weill dyschondrosteosis (LWD) is a skeletal dysplasia characterized by disproportionate short stature and the Madelung deformity of the forearm. SHOX mutations and pseudoautosomal region 1 deletions encompassing SHOX or its enhancers have been identified in approximately 60% of LWD and approximately 15% of idiopathic short stature (ISS) individuals. Recently SHOX duplications have been described in LWD/ISS but also in individuals with other clinical manifestations, thus questioning their pathogenicity.
The objective of the study was to investigate the pathogenicity of SHOX duplications in LWD and ISS.
Multiplex ligation-dependent probe amplification is routinely used in our unit to analyze for SHOX/pseudoautosomal region 1 copy number changes in LWD/ISS referrals. Quantitative PCR, microsatellite marker, and fluorescence in situ hybridization analysis were undertaken to confirm all identified duplications.
During the routine analysis of 122 LWD and 613 ISS referrals, a total of four complete and 10 partial SHOX duplications or multiple copy number (n > 3) as well as one duplication of the SHOX 5' flanking region were identified in nine LWD and six ISS cases. Partial SHOX duplications appeared to have a more deleterious effect on skeletal dysplasia and height gain than complete SHOX duplications. Importantly, no increase in SHOX copy number was identified in 340 individuals with normal stature or 104 overgrowth referrals.
MLPA analysis of SHOX/PAR1 led to the identification of partial and complete SHOX duplications or multiple copies associated with LWD or ISS, suggesting that they may represent an additional class of mutations implicated in the molecular etiology of these clinical entities.
The Journal of Clinical Endocrinology and Metabolism 02/2011; 96(2):E404-12. DOI:10.1210/jc.2010-1689 · 6.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Microdeletion of the chromosome 22q11.2 region is the most common genetic aberration among patients with velocardiofacial syndrome (VCFS) but a subset of subjects do not show alterations of this chromosome region.
We analyzed 18 patients with VCFS-like features by comparative genomic hybridisation (aCGH) array and performed a face-to-face slide hybridization with two different arrays: a whole genome and a chromosome 22-specific BAC array. Putative rearrangements were confirmed by FISH and MLPA assays.
One patient carried a combination of rearrangements on 1q21.1, consisting in a microduplication of 212 kb and a close microdeletion of 1.15 Mb, previously reported in patients with variable phenotypes, including mental retardation, congenital heart defects (CHD) and schizophrenia. While 326 control samples were negative for both 1q21.1 rearrangements, one of 73 patients carried the same 212-kb microduplication, reciprocal to TAR microdeletion syndrome. Also, we detected four copy number variants (CNVs) inherited from one parent (a 744-kb duplication on 10q11.22; a 160 kb duplication and deletion on 22q11.21 in two cases; and a gain of 140 kb on 22q13.2), not present in control subjects, raising the potential role of these CNVs in the VCFS-like phenotype.
Our results confirmed aCGH as a successful strategy in order to characterize additional submicroscopic aberrations in patients with VCF-like features that fail to show alterations in 22q11.2 region. We report a 212-kb microduplication on 1q21.1, detected in two patients, which may contribute to CHD.
BMC Medical Genetics 12/2009; 10(1):144. DOI:10.1186/1471-2350-10-144 · 2.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Screening for 22q11.2 deletions has not an easy approach due to the wide variability of their associated phenotype. Many clinical features overlap with those of other known syndromes and reported loci. Patients referred to exclude a 22q11.2 deletion are usually tested with a locus-specific FISH probe, with 10% positive cases depending on the selection criteria, but patients testing negative for FISH at 22q11.2 may have other chromosomal aberrations in routine cytogenetic analysis. We tested 819 patients suspected of having a 22q11.2 deletion. Eighty-eight patients (10.7%) were positive for 22q11.2 deletion, whereas 30 patients (3.7%) showed other chromosomal abnormalities involving deletions and duplications, derivative chromosomes, marker chromosomes, apparently balanced and unbalanced translocations and sex chromosome aneuploidies. Of these alterations, 28 did not involve region 22q11 and most had not been associated with 22q11.2 deletion phenotype before. We discuss the similarity of DiGeorge/velocardiofacial syndrome with other known clinical entities and suggest correlations between the new loci and the observed clinical features. The frequency of unrelated chromosomal anomalies reported in this study and in other previous reports highlights the importance of conventional cytogenetic analysis as an initial genome-wide screening tool in all referred patients, and provides useful data to optimize diagnostic and screening protocols according to the most frequent chromosomal findings.
American Journal of Medical Genetics Part A 05/2008; 146A(9):1134-41. DOI:10.1002/ajmg.a.32256 · 2.16 Impact Factor