[Clinical and genetic description of neuronal ceroid lipofuscinosis 6 type in the yakut family]. / Kliniko-geneticheskoe opisanie neironal'nogo tseroidnogo lipofustsinoza 6 tipa v yakutskoi sem'e.

Neuronal ceroid lipofuscinosis type 6 (NCL 6) is a rare progressive neurodegenerative disease that belongs to the group of lysosomal storage diseases. A clinical and genetic description of NCL 6 in a Yakut family was carried out. The proband and her sibling showed characteristic clinical signs, including myoclonic epilepsy, ataxia, psychomotor regression, dementia, and visual impairment. The onset of the disease in the age range from 3-4 years. The disease is caused by the frameshift mutation c.396dupT (p.Val133CysfsTer18) in exon 4 of the CLN6 in a homozygous state, which was detected using targeted next generation sequencing. Diagnosis of NCL is difficult due to the pronounced genetic heterogeneity of the disease, as well as the similarity with other hereditary metabolic diseases in clinical manifestations. The method of DNA diagnostics of NCL type 6 using NGS and direct sequencing according to Sanger has been introduced into the practice of medical genetic counseling.

[Genetic Variability and Structure of SNP Haplotypes in the DMPK Gene in Yakuts and Other Ethnic Groups of Northern Eurasia in Relation to Myotonic Dystrophy].

The genetic variability of the DMPK locus has been studied in relation to six SNP markers (rs2070736, rs572634, rs1799894, rs527221, rs915915, and rs10415988) in Yakuts with myotonic dystrophy (MD) in the Yakut population and in populations of northern Eurasia. Significant differences were observed in the allele frequencies between patients and a population sample of Yakuts for three SNP loci (rs915915, rs1799894, and rs10415988) associated with a high chance of disease manifestation. The odds ratios (OR) of MD development in representatives of the Yakut population for these three loci were 2.59 (95% CI, p = 0,004), 4.99 (95% CI, p = 0.000), and 3.15 (95% CI, p = 0.01), respectively. Haplotype TTTCTC, which is associated with MD, and haplotype GTCCTT, which was observed only in Yakut MD patients (never in MD patients of non-Yakut origin), were revealed. A low level of variability in the locus of DMRK gene in Yakuts (H(e) = 0.283) compared with other examined populations was noted. An analysis of pairwise genetic relationships between populations revealed their significant differentiation for all the examined loci. In addition, a low level of differentiation in territorial groups of Yakut populations (F(ST) = 0.79%), which was related to the high subdivision of the northern Eurasian population (F(ST) = 11.83%), was observed.

Clinical, molecular and histopathological features of short stature syndrome with novel CUL7 mutation in Yakuts: new population isolate in Asia.

BACKGROUND: In total, 43 patients having short stature syndrome in 37 Yakut families with autosomal recessive prenatal and postnatal nonprogressive growth failure and facial dysmorphism but with normal intelligence have been identified. METHODS: Because Yakuts are considered as a population isolate and the disease is rare in other populations, genomewide homozygosity mapping was performed using 763 microsatellite markers and candidate gene approach in the critical region to identify the causative gene for the short stature syndrome in Yakut. RESULTS: All families shared an identical haplotype in the same region as the identical loci responsible for 3-M and gloomy face syndromes and a novel homozygous 4582insT mutation in Cullin 7 (CUL7) was found, which resulted in a frameshift mutation and the formation of a subsequent premature stop codon at 1553 (Q1553X). Yakut patients with short stature syndrome have unique features such as a high frequency of neonatal respiratory distress and few bone abnormalities, whereas the clinical features of the other Yakut patients were similar to those of 3-M syndrome. Furthermore, abnormal vascularisation was present in the fetal placenta and an abnormal development of cartilage tissue in the bronchus of a fetus with CUL7 mutation. CONCLUSION: These findings may provide a new understanding of the clinical diversity and pathogenesis of short stature syndrome with CUL7 mutation.