The prevalence of mosaic monosomy X karyotype is 0.3% (3/906)-10 times higher than published before. Additional in silico size-selection and data analysis increases PPV for monosomy X from 61% to 73% for studied population.

Various methods of obtaining fetal skin for prenatal diagnosis of certain autosomal-recessive congenital genodermatoses have been assessed. An attempt was made to obtain fetal skin by fetoscopy in 15 patients prior to pregnancy termination for a variety of medical reasons at 18-26 weeks. Specimens were obtained only in five cases (8 successful attempts out of 48). In twelve cases, of which five had a history of a child with junctional (Herlitz type) or dystrophic (Hallopeau-Siemens type) epidermolysis bullosa or non-bullous congenital ichthyosiform erythroderma at 16-25 weeks of pregnancy, fetal skin was obtained without fetoscopy under direct ultrasonic control. Specimens were obtained in all cases (33 successful attempts out of 39). In three cases, fetal pathology was diagnosed by the method of semi-thin and ultra-thin skin sections, and the respective pregnancies were terminated.

Ataxia-telangiectasia (A-T), or Louis-Bar syndrome, is a rare neurodegenerative disorder associated with immunodeficiency. For families with at least one affected child, timely A-T genotyping during any subsequent pregnancy allows the parents to make an informed decision about whether to continue to term when the fetus is affected. Mutations in the ATM gene, which is 150 kb long, give rise to A-T; more than 600 pathogenic variants in ATM have been characterized since 1990 and new mutations continue to be discovered annually. Therefore, limiting genetic screening to previously known SNPs by PCR or hybridization with microarrays may not identify the specific pathogenic genotype in ATM for a given A-T family. However, recent developments in next-generation sequencing technology offer prompt high-throughput full-length sequencing of genomic fragments of interest. This allows the identification of the whole spectrum of mutations in a gene, including any novel ones. We report two A-T families with affected children and current pregnancies. Both families are consanguineous and originate from Caucasian regions of Russia and Azerbaijan. Before our study, no ATM mutations had been identified in the older children of these families. We used ion semiconductor sequencing and an Ion AmpliSeq™ Inherited Disease Panel to perform complete ATM gene sequencing in a single member of each family. Then we compared the experimentally determined genotype with the affected/normal phenotype distribution in the whole family to provide unambiguous evidence of pathogenic mutations responsible for A-T. A single novel SNP was allocated to each family. In the first case, we found a mononucleotide deletion, and in the second, a mononucleotide insertion. Both mutations lead to truncation of the ATM protein product. Identification of the pathogenic mutation in each family was performed in a timely fashion, allowing the fetuses to be tested and diagnosed. The parents chose to continue with both pregnancies as both fetuses had a healthy genotype and thus were not at risk of A-T.

Используемый в настоящее время в России пренатальный скрининг хромосомной патологии основан на косвенных маркерах и имеет ограничение по чувствительности и специфичности. Поэтому более перспективным является применение неинвазивного пренатального ДНК-скрининга анеуплоидий (НИПС). Целью данной работы являлась оценка возможности применения полногеномного НИПС при оказании акушерско-гинекологической помощи. Проведена валидация ДНК-скрининга на образцах с известными результатами пренатальной инвазивной диагностики (N=1134). Доказана возможность транспортировки и хранения образцов (N=477). Проведено отсроченное исследование аликвот плазмы через год после первоначального исследования (N=70). Оценены факторы, которые могут влиять на результаты НИПС - доля плодовой ДНК, индекс массы тела (ИМТ), срок беременности, мозаицизм и другие. Widely performed in Russia prenatally first-trimester screening is based on secondary markers of pathology and has limited sensitivity and specificity. The most promising alternative is the use of noninvasive prenatal screening for fetal aneuploidy (NIPS). This study aims to validate the possibility of NIPS usage for obstetric and gynecological care. DNA screening was validated on samples with known results of invasive prenatal diagnostics (N=1134). It was proven that it is possible to store and transport the samples (N=477). We studied plasma aliquot samples after one year of storage (N=70). Factors that can influence the NIPS results were also evaluated: the proportion of fetal DNA, body mass index (BMI), gestational age, mosaicism, and others.