Objective — the research was aimed at studying clinical and molecular genetic characteristics of the most common subtypes of MODY (1—3) detected by NGS. Material and methods. The study included 312 patients (162 boys and 150 girls) aged 3 months to 25 years with suspected MODY. Inclusion criteria were as follows: carbohydrate metabolism disorders of varying severity, negative titer of ICA, IA2, and GAD autoantibodies, preserved secretion of endogenous insulin. NGS technique was used for molecular genetic studies. Custom DNA Panel was used for the multiplex PCR and sequencing using the Ion Ampliseq technique. Custom Diabetes Panel included 28 genes (13 MODY candidates genes and other diabetes-associated genes). Non-synonymous mutations that were not previously described were rated as «probably pathogenic» if they had minor allele frequency of <0.1% and «pathogenic» when assessed against the ANNOVAR database. Results. Mutations in MODY candidate genes were detected in 178 (57.1%) probands. Of these, 99 mutations in GCK99 gene were found in 129 (41.4%) probands and 77 relatives, 20 mutations in HNF1A gene were found in 19 (6.1%) probands and 14 relatives, 8 mutations in HNF4A gene — in 9 (2.9%) probands and 3 relatives. All detected mutations were heterozygous. MODY1 subtype was not previously described in the Russian Federation. Conclusions. The Russian population is dominated by MODY2 subtype. Only MODY2 is characterized by typical clinical presentation. NGS is a highly effective method in the diagnosis of MODY.

The diagnosis of MODY should be verified by molecular genetic analysis. Recently the introduction of next-generation sequencing, allowing simultaneous analysis of several candidate genes, greatly facilitates the diagnosis of monogenic diseases including MODY. In addition, the simultaneous analysis of several candidate genes allows to identify cases with digenic and oligogenic inheritance. In this work we present the first description of MODY cases with digenic and oligogenic inheritance in our country.Aim — to characterize MODY cases with digenic and oligogenic inheritance as defined by targeted next-generation sequencing.Material and methods. 256 subjects (age range, 0.3—25 yrs; males, n=149, females, n=107) were included in the study. The patients fulfilled the following MODY criteria: diabetes or intermediate hyperglycemia, absence of β-cell autoimmunity (ICA, GAD, IA2, IAA antibodies), preserved C-peptide secretion. Molecular genetic analysis was performed by next-generation sequencing using custom Ion Ampliseq gene panel and PGM semiconductor sequencer (Ion Torrent). All mutations were confirmed by Sanger sequencing.Results. 10 patients (8 probands, 1 sibling and 1 parent) showed digenic inheritance of MODY: 3 patients with combination of mutations in 2 candidate genes of MODY, 7 — in a candidate genes of MODY and another gene, associated with diabetes mellitus. In 1 case (sibling) showed oligogenic inheritance (mutations in GCK, HNF4A and INSR genes). Seven of the identified mutations were not previously described.Conclusion. Next-generation sequencing is useful in identifying of MODY cases with digenic and oligogenic inheritance, which is extremely important with potentially modifying effect on the phenotype.

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Wolcott—Rallison syndrome (WRS) is a rare genetic disease inherited in autosomal recessive way. Сlinical manifestations develop in early infancy with symptoms of permanent neonatal diabetes mellitus (PNDM), skeletal dysplasia, short stature and hepatic dysfunction. The condition has poor prognosis and most patients die at a young age due to episodes of acute liver or renal failure. To date about 60 genetically proved cases of WRS have been reported worldwide. The disease is most common in countries where consanguineous marriages are frequent, such as the Saudi Arabia (60% cases of PNDM patients), India, Turkey, Pakistan and North Africa. In Russian Federation WRS patients have not been described earlier.