Expanding the phenotypic spectrum of ECEL1-related congenital contracture syndromes.

Using a combination of homozygosity mapping and whole-exome sequencing (WES), we identified a novel missense c.1819G>A mutation (G607S) in the endothelin-converting enzyme-like 1 (ECEL1) gene in a consanguineous pedigree of Turkish origin presenting with a syndrome of camptodactyly, scoliosis, limited knee flexion, significant refractive errors and ophthalmoplegia. ECEL1 mutations were recently reported to cause recessive forms of distal arthrogryposis. This report expands on the molecular basis and the phenotypic spectrum of ECEL1-associated congenital contracture syndromes.

Homozygous feature of isolated triphalangeal thumb-preaxial polydactyly linked to 7q36: no phenotypic difference between homozygotes and heterozygotes.

Preaxial polydactyly is a common limb malformation in humans with variable clinical expression. Different types of triphalangeal thumb-preaxial polydactyly phenotypes were mapped to the chromosome 7q36 region. We studied a large Turkish family of 69 individuals, of whom 22 individuals were affected. In all, 11 affected family members were clinically and radiologically evaluated. All affected individuals had a triphalangeal thumb and a preaxial (hypoplastic) extra digit bilaterally, with minimal intrafamilial variation. No feet involvement was observed. Linkage and haplotype analyses using 20 informative meioses confirmed the 7q36 region contained the LIMBR1 gene. Maximum logarithm of the odds (LOD) scores were obtained with DNA markers D7S550 and D7S2423. We have further identified a novel C to T alteration at position 4909 bp in the critical zone of polarizing activity regulatory sequence (ZRS) region, in the intron 5, of the LMBR1 gene. One affected male with homozygous status and no phenotypic difference from affected family members with heterozygous status represented the first homozygote case of the triphalangeal thumb-preaxial polydactyly phenotype.

Skewed X inactivation in an X linked nystagmus family resulted from a novel, p.R229G, missense mutation in the FRMD7 gene.

AIMS: This study aimed to identify the underlying genetic defect of a large Turkish X linked nystagmus (NYS) family. METHODS: Both Xp11 and Xq26 loci were tested by linkage analysis. The 12 exons and intron-exon junctions of the FRMD7 gene were screened by direct sequencing. X chromosome inactivation analysis was performed by enzymatic predigestion of DNA with a methylation-sensitive enzyme, followed by PCR of the polymorphic CAG repeat of the androgen receptor gene. RESULTS: The family contained 162 individuals, among whom 28 had NYS. Linkage analysis confirmed the Xq26 locus. A novel missense c.686C>G mutation, which causes the substitution of a conserved arginine at amino acid position 229 by glycine (p.R229G) in exon 8 of the FRMD7 gene, was observed. This change was not documented in 120 control individuals. The clinical findings in a female who was homozygous for the mutation were not different from those of affected heterozygous females. Skewed X inactivation was remarkable in the affected females of the family. CONCLUSIONS: A novel p.R229G mutation in the FRMD7 gene causes the NYS phenotype, and skewed X inactivation influences the manifestation of the disease in X linked NYS females.

An apparently dominant bipolar affective disorder (BPAD) locus on chromosome 20p11.2-q11.2 in a large Turkish pedigree.

Bipolar affective disorder (BPAD), also known as manic-depressive illness, is a common complex, polygenic disorder characterised by recurrent cyclic episodes of mania and depression. Family, twin, and adoption studies strongly suggest a genetic predisposition/susceptibility to BPAD, but no genes have yet been identified. We studied a large Turkish pedigree, with an apparently autosomal dominant BPAD, which contained 13 affected individuals. The age of onset ranged from 15-40 with a mean of 25 years. The phenotypes consisted of recurrent manic and major depressive episodes, including suicidal attempts; there was usually full remission with lithium treatment. A genome-wide linkage analysis using a dominant mode of inheritance showed strong evidence for a BPAD susceptibility locus on chromosome 20p11.2-q11.2. The highest 2-point lod score of 4.34 at theta = 0 was obtained with markers D20S604, D20S470, D20S836 and D20S838 using a dominant model with full penetrance. Haplotype analysis enabled the mapping of the BPAD locus in this family between markers D20S186 and D20S109, to a region of approximately 42 cM.