Mental retardation (MR) is found in about 1% of the population. Intellectual disability can be caused by various etiological factors. About 40% of cases MR are associated with genetic factors. The review aims are reflection of historical stages of studying the nature of intellectual disability and evaluation of dynamics of diagnostic efficiency of genetic forms of MR with the introduction modern research methods. The sources for the review were collected in the databases PubMed, Cochrane, Google Scholar etc. in the period from 1943 to 2020. Diagnostic efficiency of MR has increased from 3,7% to 42% over the last decades. Despite the improvement of diagnostic methods of genetic forms of intellectual disability, the etiology of MR remains unclear in most cases.

Chronic pancreatitis is the multifactorial disease, genetic and environmental factors play a role in the development of it. The aim was to determine the contribution of rs213950 CFTR gene to the risk of chronic pancreatitis (CP). DNA samples obtained from 302 unrelated patients with chronic pancreatitis and 465 unrelated individuals without gastrointestinal diseases. Genotyping was performed using the PCR method with discrimination of alleles using TaqMan probes. The χ2 criterion and the odds ratio (OR) with 95% confidence intervals (CI) were used to assess the associations of alleles and genotypes of genes with the risk of the disease. We found an association of the A allele rs213950 of the CFTR gene with an increased risk of chronic pancreatitis (OR=1,24, CI 95%=1,01-1,53, P=0,04). Also, the risk of CP increased in smokers with the A/G-A/A genotypes (OR=2,07, CI 95%=1,13-3,78, P=0,017D) and with alcohol abuse for more than 10 years in carriers of the A/A genotype (OR=2,23, CI 95%=1,12-4,47, P=0,02R). The frequency and volume of alcohol consumed in carriers of the rs213950 polymorphism of the CFTR gene didn’t reveal statistically significant differences.

The study of the relationship between mutations in the MEFV (MEditerranean FeVer) gene and infertility creates opportunity for optimizing the diagnosis and prevention of reproductive disorders in women with familial Mediterranean fever (FMF). Data were collected from the patients registered in 1998- 2018 at the Center for Medical Genetics and Primary Health Care. From the cohort of 32000 patients analyzed for mutations in the MEFV gene, only women (4577) of reproductive age (18-49 years old) were selected, with clinical diagnosis FMF according to the International Tel-Hashomer criteria and confirmed by genetic testing. Comprehensive monitoring of reproductive function was performed in 373 women - 211 FMF patients and 162 non FMF women with reproductive disorders. Homozygous genotype M694V/M694V (11.5%) is associated with severe disease and renal amyloidosis (1.5%) (p=0.028). Infertility was revealed in 90.9% patients homozygous for M694V and 100% for M680I mutations (p<0.009). M694V mutation in population of women of reproductive age was more common in FMF patients with infertility (68.8%) compare to fertile women (31.2%) (p<0.009). A clear correlation between irregular uptakes or a low dose of colchicine and infertility among investigated FMF patients (88.4%) (p <0.001) was revealed. A delayed diagnosis of over 10 years was observed in 80.7% of infertile patients with FMF compared with 19.3% in fertile women (p<0.007). Infertility is largely associated with homozygous M694V or M680I genotypes of MEFV gene. Patients with FMF have a comparable prior-reproductive system with healthy controls. Infertility is formed under the influence of modifying factors such as social status, irregular intake of colchicine, and delayed diagnosis for more than 10 years.

Interchromosomal insertion is a rare balanced chromosomal rearrangement that occur when an interstitial segment of one chromosome is translocated into another non-homologous chromosome. Carriers of insertions display normal phenotype and fertility, but have an increased risks of spontaneous abortions (SA) and viable offspring with inherited chromosomal imbalance. The aim of study: to assess the interchromosomal ins(11;2)(q21;q31.1q32.3) segregation to determine the genetic risk of inheriting an unbalanced karyotype by the outcome; to analyze segmental mono- and trisomy 2q31.1q32.3 phenotypic manifestations.Family with reproductive failure history was investigated using a clinical, genealogical, ultrasound, cytogenetical (GTG-banding) and morphological methods. Risks of reproductive loss and aneusomic offspring birth were calculated. The outcome prognosis and prenatal diagnostics results were discussed. Clinical, cytogenetical and reproductive history data of carriers ins(11;2) (q21;q31.1q32.3) were presented. The size of insertional segment is about 0,8-0,9% haploid autosomal length (HAL). Outcomes of 15 pregnancies of 6 carriers were as follows: rate of miscarries - 20%, one miscarriage - fetus with karyotype 46,XY, 3 cases - chromosomal imbalance. The segregation ratio for normal:balanced:der(2):der(11) is 3:6:1:1; the empirical risk for forming aneuploid zygotes is 18% (2/11). Segmental monosomy 2q31.1q32.1 phenotypic features in 2 presented patients are similar with clinical signs of 18 previously reported live-born children with monosomy 2q31q33. Ectrodactyly in 2 our patients confirms association of malformation with 2q31.1 region loss. The presented and reported cases data illustrate a possibility of giving birth of offspring with segmental monosomy as well as trisomy 2q31q32, risk of viable offspring with inherited imbalance may be estimated as 30-40%, spontaneous abortions rate - 20-33%. Fetus with trisomy 2q31.1q32.3 showed unspecific signs of autosomal imbalance. Pattern of phenotypical features reported in 2 relatives with der(2)ins(11;2) correlates with clinically recognizable monosomy 2q31q32 syndrome. Microcephaly, cleft palate/cleft lip and palate, ectrodactyly are the main diagnostic markers of fetal pathology which can be identified using prenatal ultrasound investigation.

The number of copies of tandem ribosomal repeat (rDNA) in the DNA of blood leukocytes of patients with cystic fibrosis of various ages (from 0 to 66 years) was determined for the first time. It was shown that the genomes of patients with cystic fibrosis contain an increased number of rDNA copies (289 - 932; mean: 563 ± 101; N = 203) compared with healthy people (171 - 711; mean 420 ± 107 copies; N = 751) of the same age (p <10-33). In the sample of patients and in the control sample, a narrowing of the range of variation in the rDNA copy number was observed in older age groups. In the group of patients aged 30-66 years, the interval of variation in the number of rDNA copies in the genome was narrowed to 430-680 copies (mean: 544 ± 72 copies; N = 27). Potentially, the number of rDNA copies in the genome of patients with cystic fibrosis can be considered an additional prognostic marker reflecting the patient’s life expectancy.