[Show abstract][Hide abstract] ABSTRACT: Congenital nystagmus (NYS) is characterized by bilateral, spontaneous, and involuntary movements of the eyeballs that most commonly presents between 2 and 6 months of life. To date, 44 different FRMD7 gene mutations have been found to be etiological factors for the NYS1 locus at Xq26-q27. The aim of this study was to find the FRMD7 gene mutations in a large eleven-generation Indian pedigree with 71 members who are affected by NYS. Mutation analysis of the entire coding region and splice junctions of the FRMD7 gene revealed a novel missense mutation, c.A917G, predicts a substitution of Arg for Gln at codon 305 (Q305R) within exon 10 of FRMD7. The mutation was detected in hemizygous males, and in homozygous and heterozygous states in affected female members of the family. This mutation was not detected in unaffected members of the family or in 100 unrelated control subjects. This mutation was found to be at a highly conserved residue within the FERM-adjacent domain in affected members of the family. Structure prediction and energetic analysis of wild-type FRMD7 compared with mutant (Q305R) revealed that this change in amino acid led to a change in secondary structure predicted to be an energetically unstable protein. The present study represents the first confirmation of FRMD7 gene mutations in a multigenerational Indian family and expands the mutation spectrum for this locus.
European journal of human genetics: EJHG 04/2012; 20(10):1032-6. · 3.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Omphalocele is a congenital birth defect characterised by the presence of internal organs located outside of the ventral abdominal wall. The purpose of this study was to identify the underlying genetic mechanisms of a large autosomal dominant Caucasian family with omphalocele.
A genetic linkage study was conducted in a large family with an autosomal dominant transmission of an omphalocele using a genome-wide single nucleotide polymorphism (SNP) array. The analysis revealed significant evidence of linkage (non-parametric NPL = 6.93, p=0.0001; parametric logarithm of odds (LOD) = 2.70 under a fully penetrant dominant model) at chromosome band 1p31.3. Haplotype analysis narrowed the locus to a 2.74 Mb region between markers rs2886770 (63014807 bp) and rs1343981 (65757349 bp). Molecular characterisation of this interval using array comparative genomic hybridisation followed by quantitative microsphere hybridisation analysis revealed a 710 kb duplication located at 63.5-64.2 Mb. All affected individuals who had an omphalocele and shared the haplotype were positive for this duplicated region, while the duplication was absent from all normal individuals of this family. Multipoint linkage analysis using the duplication as a marker yielded a maximum LOD score of 3.2 at 1p31.3 under a dominant model. The 710 kb duplication at 1p31.3 band contains seven known genes including FOXD3, ALG6, ITGB3BP, KIAA1799, DLEU2L, PGM1, and the proximal portion of ROR1. Importantly, this duplication is absent from the database of genomic variants.
The present study suggests that development of an omphalocele in this family is controlled by overexpression of one or more genes in the duplicated region. To the authors' knowledge, this is the first reported association of an inherited omphalocele condition with a chromosomal rearrangement.
Journal of Medical Genetics 04/2012; 49(4):270-6. · 5.70 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Myopia is a common vision problem affecting almost one third of the world's population. It can occur as an isolated genetic condition or be associated with other anomalies and/or syndromes. Seventeen myopia loci have been identified on various chromosomes; however, no specific gene mutations have yet been identified.
Two large multigeneration Asian Indian pedigrees (UR006 and UR077) with isolated, nonsyndromic myopia were studied, in which the condition appeared to segregate as an X-linked recessive trait (MYP1; MIM 310460). The degree of myopia was variable in both families, ranging from -6 to -23 D (mean, -8.48 D) with the majority >7.0 D. To map the myopia locus in these families, polymorphic microsatellite markers covering the entire X chromosome were used in linkage analyses performed on 42 genomic DNA samples (13 affected and 29 normal) from both families.
Marker DXYS154, which is located within the pseudoautosomal region in distal Xq28 (PAR2; pseudoautosomal region 2), gave a combined maximum LOD score of 5.3 at = 0 under an autosomal recessive model. Other markers in the region (near but not within the PAR2 region) that showed no recombination with the phenotype in both the families included DXS1108, DXS8087, and F8i13.
Observation of recombination in family UR006 refined the disease locus to a ∼1.25-Mb region flanked by the proximal marker DXS1073 and distal marker DXYS154. Mutation search in exons and splice junctions of candidate genes CTAG2, GAB3, MPP1, F8Bver, FUNDC2, VBP1, RAB39B, CLIC2, TMLHE, SYBL, IL9R, SPRY3, and CXYorf1 did not detect a pathogenic or predisposing variant.
[Show abstract][Hide abstract] ABSTRACT: Myopia is the most common human eye disorder with complex genetic and environmental causes. To date, several myopia loci have been identified in families of different geographic origin. However, no causative gene(s) have yet been identified. The aim of this study was the characterization of Polish families with high-grade myopia, including genetic analysis.
Forty-two multiplex Polish families with non-syndromic high-grade myopia participated in the study. All family members underwent detailed ophthalmic examination and high-grade myopia was defined as ≤-6.0 diopters (D) based on the spherical refractive error. A genome-wide single nucleotide polymorphism (SNP)-based high-density linkage scan was performed using Affymetrix Human SNP Array 6.0 on a selected family (HM-32) with multiple affected individuals.
Nonparametric linkage analysis identified three novel loci in family HM-32 at chromosome 7p22.1-7p21.1 ([NPL] 8.26; p=0.006), chromosome 7p12.3-7p11.2 ([NPL] 8.23; p=0.006), and chromosome 12p12.3-12p12.1 ([NPL] 8.02; p=0.006), respectively. The effect of linkage disequilibrium on linkage due to dense SNP map was addressed by systematically pruning SNPs from the linkage panel.
Haplotype analysis with informative crossovers in affected individuals defined a 12.2; 10.9; and 9.5 Mb genomic regions for high-grade myopia spanned between SNP markers rs11977885/rs10950639, rs11770622/rs9719399, and rs4763417/rs10842388 on chromosomes 7p22.1-7p21.1, 7p12.3-7p11.2, and 12p12.3-12p12.1, respectively.
[Show abstract][Hide abstract] ABSTRACT: Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition characterized by swollen, painful, inflamed lesions in the axillae, groin, armpits and other parts of the body that contain apocrine glands. The aetiology of HS is unknown, and earlier reports indicate genetic locus responsible for this phenotype on chromosome 1p21.1-1q25.3, but no causative gene(s) have yet been identified. We studied two large multigeneration pedigrees (UR251 and UR252), in which the condition appeared to segregate as an autosomal dominant trait with 100% penetrance. No skipping of generations was observed in either family. Pedigrees consist of 96 individuals, including 25 affected individuals. Because of squamous cell carcinoma, a few deaths were reported in family UR0251. The locus on chromosome 1p21.1-1p25.3, known from previous studies is associated with HS, was excluded in both families by linkage and haplotype analyses. Further studies are in progress to identify the region that is associated with the phenotype in these families.
[Show abstract][Hide abstract] ABSTRACT: Keratoconus (KTCN) is a noninflammatory thinning and anterior protrusion of the cornea that results in steepening and distortion of the cornea, altered refractive powers, and reduced visual acuity. Several loci responsible for a familial form of KTCN have been mapped, however; no mutations in any genes have been identified for any of these loci. There is also evidence that VSX1 and SOD1 may be involved in the etiology of KTCN. The purpose of this study was to verify the available data and to identify a new keratoconus susceptibility locus.
KTCN without other ocular or systemic features was diagnosed in 18 families. VSX1 and SOD1 sequencing was performed on affected individuals and control subjects. Genomewide linkage analysis was then performed in all families using polymorphic microsatellite markers with an average spacing of 5 cM. Next, single-nucleotide polymorphism (SNP) arrays, fluorescence in situ hybridization (FISH) analysis, and a comparative genomic hybridization array were used in one family to assess a candidate region on 13q32.
All previously reported KTCN loci were excluded. VSX1 and SOD1 were sequenced, and no potentially functional variants were found. One KTCN family yielded a maximum multipoint parametric LOD score of 4.1 and multipoint nonparametric linkage (NPL) LOD score of 3.2. Multipoint linkage and haplotype analysis narrowed the locus to a 5.6-Mb region between the SNPs rs9516572 and rs3825523 on 13q32.
The results exclude VSX1 and SOD1 as potential disease-causing genes in these families and localize a novel gene for keratoconus to a 5.6-Mb interval on 13q32.
[Show abstract][Hide abstract] ABSTRACT: Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is one of the most common congenital facial defects, with an incidence of 1 in 700-1,000 live births among individuals of European descent. Several linkage and association studies of NSCL/P have suggested numerous candidate genes and genomic regions. A genomewide linkage analysis of a large multigenerational family (UR410) with NSCL/P was performed using a single-nucleotide-polymorphism array. Nonparametric linkage (NPL) analysis provided significant evidence of linkage for marker rs728683 on chromosome 18q21.1 (NPL=43.33 and P=.000061; nonparametric LOD=3.97 and P=.00001). Parametric linkage analysis with a dominant mode of inheritance and reduced penetrance resulted in a maximum LOD score of 3.61 at position 47.4 Mb on chromosome 18q21.1. Haplotype analysis with informative crossovers defined a 5.7-Mb genomic region spanned by proximal marker rs1824683 (42,403,918 bp) and distal marker rs768206 (48,132,862 bp). Thus, a novel genomic region on 18q21.1 was identified that most likely harbors a high-risk variant for NSCL/P in this family; we propose to name this locus "OFC11" (orofacial cleft 11).
The American Journal of Human Genetics 08/2007; 81(1):180-8. · 11.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Split-hand/foot malformation with long-bone deficiency (SHFLD) is a rare, severe limb deformity characterized by tibia aplasia with or without split-hand/split-foot deformity. Identification of genetic susceptibility loci for SHFLD has been unsuccessful because of its rare incidence, variable phenotypic expression and associated anomalies, and uncertain inheritance pattern. SHFLD is usually inherited as an autosomal dominant trait with reduced penetrance, although recessive inheritance has also been postulated. We conducted a genomewide linkage analysis, using a 10K SNP array in a large consanguineous family (UR078) from the United Arab Emirates (UAE) who had disease transmission consistent with an autosomal dominant inheritance pattern. The study identified two novel SHFLD susceptibility loci at 1q42.2-q43 (nonparametric linkage [NPL] 9.8, P=.000065) and 6q14.1 (NPL 7.12, P=.000897). These results were also supported by multipoint parametric linkage analysis. Maximum multipoint LOD scores of 3.20 and 3.78 were detected for genomic locations 1q42.2-43 and 6q14.1, respectively, with the use of an autosomal dominant mode of inheritance with reduced penetrance. Haplotype analysis with informative crossovers enabled mapping of the SHFLD loci to a region of approximately 18.38 cM (8.4 Mb) between single-nucleotide polymorphisms rs1124110 and rs535043 on 1q42.2-q43 and to a region of approximately 1.96 cM (4.1 Mb) between rs623155 and rs1547251 on 6q14.1. The study identified two novel loci for the SHFLD phenotype in this UAE family.
The American Journal of Human Genetics 02/2007; 80(1):105-11. · 11.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Nonsyndromic cleft lip with or without cleft palate (CL-P) is a common congenital anomaly with incidence ranging from 1 in 300 to 1 in 2,500 live births. We analyzed two Indian pedigrees (UR017 and UR019) with isolated, nonsyndromic CL-P, in which the anomaly segregates as an autosomal dominant trait. The phenotype was variable, ranging from unilateral to bilateral CL-P. A genomewide linkage scan that used approximately 10,000 SNPs was performed. Nonparametric linkage (NPL) analysis identified 11 genomic regions (NPL>3.5; P<.005) that could potentially harbor CL-P susceptibility variations. Among those, the most significant evidence was for chromosome 13q33.1-34 at marker rs1830756 (NPL=5.57; P=.00024). This was also supported by parametric linkage; MOD score (LOD scores maximized over genetic model parameters) analysis favored an autosomal dominant model. The maximum LOD score was 4.45, and heterogeneity LOD was 4.45 (alpha =100%). Haplotype analysis with informative crossovers enabled the mapping of the CL-P locus to a region of approximately 20.17 cM (7.42 Mb) between SNPs rs951095 and rs726455. Thus, we have identified a novel genomic region on 13q33.1-34 that harbors a high-risk variant for CL-P in these Indian families.
The American Journal of Human Genetics 10/2006; 79(3):580-5. · 11.20 Impact Factor