Early infantile epileptic encephalopathies (EIEE) are a group of disorders characterized by pharmacoresistant epileptic seizures manifesting in infancy and leading to psychomotor retardation. The most common genetic variant with X-linked dominant inheritance is type 2 EIEE associated with CDKL5 gene mutations. We evaluated the prevalence of this type of EIEE among Russian patients (n = 148) with epileptic seizures manifesting in infancy and analyzed their clinical and genetic characteristics. We performed exome sequencing for all patients; 15 (10 %) of them (aged between 2 months and 5 years) were found to have CDKL5 gene mutations and were, therefore, diagnosed with type 2 EIEE. The results of correlation analysis suggest that the severity of clinical manifestations of type 2 EIEE is largely determined by the location of mutations affecting the function of the protein encoded by this gene. This is important to ensure better understanding of type 2 EIEE etiology and predict it severity in patients with different allelic variants.

Achromatopsia (ACHM) is a rare autosomal recessive disease. Its mutation spectrum is well described in other populations, but the data on ACHM prevalence and features in Russia are insufficient. Purpose . To describe clinically and genetically the Russian cohort of AHCM for the potential use of targeted treatment approaches, including gene therapy. Material and methods . Out of 18 patients with clinical manifestations of ACHM, 10 patients were chosen (6 with no kinship relatedness and 4 with kinship relatedness) aged 12.3 ± 5.8 years. These patients underwent standard ophthalmologic examination: visometry, perimetry, biomicroscopy, ophthalmoscopy, as well as optical coherence tomography, electroretinography, and color test on distinguishing color shades, in order to determine the clinical characteristics of ACHM. Molecular genetic confirmation of the clinical diagnosis was performed by high-performance parallel DNA sequencing. An in silico analysis of pathogenetic pathways of the clinical picture in 10 patients with confirmed ACHM was performed. Results . In the examined Russian patients, previously determined mutations in the CNGA3 and CNGB3 genes were confirmed. The most common mutation was a single nucleotide deletion with a reading frame shift in the 10th exon of the CNGB3 gene; a missense mutation in the 8th exon of the CNGA3 gene was second frequent. One patient had mutations in the CNGA3 and CNGB3 genes. Segregation analysis confirms the autosomal recessive nature of disease inheritance. Mutations in the CNGB3 gene have been observed to lead to more serious clinical manifestations than mutations in CNGA3. Conclusions . The analysis of the Russian ACHM cohort shows that mutations in the CNGA3 and CNGB3 genes are the main cause of the development of the disease. A complete molecular genetic confirmation of the clinical diagnosis has been obtained, which is necessary for prescribing targeted treatment to patients, including gene therapy.

Achromatopsia (ACHM) is a rare autosomal recessive disease. Its mutation spectrum is well described in other populations, but the data on ACHM prevalence and features in Russia are insufficient. Purpose. To describe clinically and genetically the Russian cohort of AHCM for the potential use of targeted treatment approaches, including gene therapy. Material and methods. Out of 18 patients with clinical manifestations of ACHM, 10 patients were chosen (6 with no kinship relatedness and 4 with kinship relatedness) aged 12.3 ± 5.8 years. These patients underwent standard ophthalmologic examination: visometry, perimetry, biomicroscopy, ophthalmoscopy, as well as optical coherence tomography, electroretinography, and color test on distinguishing color shades, in order to determine the clinical characteristics of ACHM. Molecular genetic confirmation of the clinical diagnosis was performed by high-performance parallel DNA sequencing. An in silico analysis of pathogenetic pathways of the clinical picture in 10 patients with confirmed ACHM was performed. Results. In the examined Russian patients, previously determined mutations in the CNGA3 and CNGB3 genes were confirmed. The most common mutation was a single nucleotide deletion with a reading frame shift in the 10th exon of the CNGB3 gene; a missense mutation in the 8th exon of the CNGA3 gene was second frequent. One patient had mutations in the CNGA3 and CNGB3 genes. Segregation analysis confirms the autosomal recessive nature of disease inheritance. Mutations in the CNGB3 gene have been observed to lead to more serious clinical manifestations than mutations in CNGA3. Conclusions. The analysis of the Russian ACHM cohort shows that mutations in the CNGA3 and CNGB3 genes are the main cause of the development of the disease. A complete molecular genetic confirmation of the clinical diagnosis has been obtained, which is necessary for prescribing targeted treatment to patients, including gene therapy.

The authors present an unique familial case of ataxia-telangiectasia (AT) mimicking autosomal dominant inheritance with different phenotypes in a 3-year-old boy (ataxia and moderate dyskinesia since 1.5 years) and his 31-year-old mother (mild dystonia, predominantly torticollis, since 10 years). Exome sequencing of the boy detected two heterozygous ATM mutations c.1564_1565delGA (p.Glu522fs) and c.6154G>A (p.Glu2052Lys) reported earlier. Sanger sequencing found both mutations in the child, the father was heterozygous for c.1564_1565delGA, the mother for 6154G>A earlier reported in the rare A-T phenotype of 'pure' local dystonia. Exome sequencing of the mother, who considered herself healthy, detected the allelic ATM mutation c.7630-2A>C in intron 51.