CD3Z polymorphisms and promoter hypermethylation in dermatomyositis - the role of cytosine-phosphate-guanine-related single nucleotide polymorphisms.

BACKGROUND: Decreased expression of the T cell receptor (TCR) ζ-chain has been reported in autoimmune diseases. Recent evidence suggests that this deficiency may be due to polymorphisms in the CD3Z (CD247) gene and/or due to promoter hypermethylation. METHODS: Altogether 131 subjects - 36 with dermatomyositis (DM) and 95 healthy controls were genotyped for rs1052230 G > C and rs1052231 T > A polymorphisms using TaqMan assay. The rs840015 G > A polymorphism was analyzed by direct sequencing. The promoter methylation status was analyzed by Sanger sequencing of bisulfite converted DNA. RESULTS: The rs1052230GC genotype and C allele and the rs1052231TA genotype and T allele were found to correlate with photosensitivity as well as the rs1052230C/rs1052231T haplotype. The rs1052231TA genotype was found to be associated with cutaneous disease. The rs840015GG genotype was found increased among patients with DM, leading to increased OR 2.4. On the contrary, the rs840015GA genotype appeared to be protective for the development of DM. From the 11 cytosine-phosphate-guanine (CpG) islands analyzed, only the 8th island showed a difference in its methylation due to the polymorphism rs840015 G > A within this island, as our results suggest. In this way the presence of AA genotype led to no methylation and the presence of the GG genotype was associated with hemimethylation. CONCLUSION: The CD247 rs1052230 G > C and rs1052231 T > A polymorphisms appeared to have a disease-modifying role. The rs840015GA genotype being associated with reduced methylation has a protective role for the development of dermatomyositis and our results suggest that CpG related single nucleotide polymorphisms may play an important role in autoimmunity.

Chromosomal microarray analysis of Bulgarian patients with epilepsy and intellectual disability.

High resolution chromosomal microarray analysis (CMA) has facilitated the identification of small chromosomal rearrangements throughout the genome, associated with various neurodevelopmental phenotypes, including ID/DD. Recently, it became evident that intellectual disability (ID)/developmental delay (DD) can occur with associated co-morbidities like epileptic seizures, autism and additional congenital anomalies. These observations require whole genome approach in order to detect the genetic causes of these complex disorders. In this study, we examined 92 patients of Bulgarian origin at age between 1 and 22 years with ID, generalized epilepsy, autistic signs and congenital anomalies. CMA was carried out using SurePrint G3 Human CGH Microarray Kit, 4 × 180 K and SurePrint G3 Unrestricted CGH ISCA v2, 4 × 180 K oligo platforms. Referral indications for selection of the patients were the presence of generalized refractory seizures disorders and co-morbid ID. Clearly pathogenic copy number variations (CNVs) were detected in eight patients (8.7%) from our cohort. Additionally, possibly pathogenic rearrangements of unclear clinical significance were detected in six individuals (6.5%), which make for an overall diagnostic yield of 15.2% among our cohort of patients. We report here the patients with clearly pathogenic CNVs, discuss the potential causality of the possibly pathogenic CNVs and make genotype - phenotype correlations. One novel possibly pathogenic heterozygous deletion in 15q22.31 region was detected in a case with ID/DD. Additionally, whole APBA2 gene duplication in 15q13.1 was found in three generations of a family with epilepsy, ID and psychiatric abnormalities. The results from this study allow us to define the genetic diagnosis in a subset of Bulgarian patients and improve the genetic counseling of the affected families. To our knowledge, this is the first aCGH evaluation of a Bulgarian cohort of children with epilepsy and ID so far.

Hereditary spastic paraplegia 3A associated with axonal neuropathy.

OBJECTIVE: To study the frequency and distribution of mutations in SPG3A in a large cohort of patients with hereditary spastic paraplegia. DESIGN: We screened a large cohort of 182 families and isolated cases with pure or complex hereditary spastic paraplegia phenotypes, which were negative for mutations in SPG4. RESULTS: In 12 probands (6.6%), we identified 12 different SPG3A mutations (11 missense and 1 insertion/frameshift) of which 7 were novel and 3 were de novo. We found incomplete penetrance in 1 family (G482V). In most cases, SPG3A mutations were associated with an early age at onset (mean, 3 y); however, in 1 family (R495W mutation), symptoms started later (mean, 14 y) with clear intrafamilial variability (8-28 y). Six patients with an SPG3A mutation (F151S, Q191R, M408T, G469A, R495W) originating from 5 unrelated families presented with a complex form of hereditary spastic paraplegia associated with a neuropathy (17%). Our electrophysiological and pathological findings confirmed an axonal sensory-motor neuropathy. There was no correlation between the genotype and the presence of a neuropathy. CONCLUSIONS: We conclude that mutations in SPG3A represent an important cause of patients in the overall hereditary spastic paraplegia population. SPG3A is more often associated with a neuropathy than previously assumed. Therefore, patients with a bipyramidal syndrome and a neuropathy should be screened for mutations in SPG3A.

Dominant intermediate Charcot-Marie-Tooth type C maps to chromosome 1p34-p35.

Dominant intermediate Charcot-Marie-Tooth (DI-CMT) neuropathy is a genetic and phenotypic variant of classical CMT, characterized by intermediate nerve conduction velocities and histological evidence of both axonal and demyelinating features. We report two unrelated families with intermediate CMT linked to a novel locus on chromosome 1p34-p35 (DI-CMTC). The combined haplotype analysis in both families localized the DI-CMTC gene within a 6.3-cM linkage interval flanked by markers D1S2787 and D1S2830. The functional and positional candidate genes, Syndecan 3 (SDC3), and lysosomal-associated multispanning membrane protein 5 (LAPTM5) were excluded for pathogenic mutations.