Clinical and genetic description of neuronal ceroid lipofuscinosis 6 type in the yakut family

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.