Сочетание инвертированной дупликации с терминальной делецией 8р (invdupdel(8p)) – редкая хромосомная перестройка, проявляющаяся задержкой нейропсихического развития, умственной отсталостью, пороками сердца и аномалиями мозга. Известно, что полиморфная парацентрическая инверсия в структуре хромосомы 8 матери может привести к перестройке invdupdel(8р) у ее ребенка. Нами создана система зондов для поиска FISH-методом скрытой инверсии в хромосоме 8 матери пациента с задержкой развития, гипотонией, черепно-лицевыми аномалиями и кольцевой хромосомой 8, обусловленной invdupdel(8р). Инверсия в структуре хромосомы 8 у женщины выявлена, что указывает на необходимость проведения пренатальной диагностики при наступлении беременности. The combination of an inverted duplication with a terminal 8p deletion (invdupdel(8p)) is a rare chromosomal rearrangement that manifests with neurodevelopmental delay, intellectual disability, heart defects, and brain abnormalities. It is known that a polymorphic paracentric inversion in the structure of mother’s chromosome 8 can lead to invdupdel(8p) in her child. We have created a system of DNA-probes to search with the FISH-method for cryptic inversion in chromosome 8 of the mother of a patient with developmental delay, muscle hypotonia, craniofacial anomalies and ring chromosome 8 caused by invdupdel(8p). An inversion in the structure of chromosome 8 in a woman was revealed, which indicates the need for prenatal diagnosis in the case of pregnancy.

Introduction The deductive method: from karyotyping to aCGH and WES is an important aspect in the diagnosis and search for the causes of intellectual disability due to congenital brain anomalies. There is recommendation to exclude the presence of CNV or monogenic variants for patients with a normal karyotype, but with a clinical picture of syndromic disease. Objectives Improvement of diagnosis of intellectual disability. Methods aCGH with 60K Agilent microarrays, WES with SureSelect Human All Exon V8 Results Pathogenic or potentially pathogenic CNVs were excluded previously by aCGH for 10 families (total 32 people, 2 families had 2 children) with intellectual disability and congenital brain anomalies (for example, polymicrogyria, pachygyria, lissencephaly). The WES identified candidate variants for all families that can lead to impaired neurodevelopment, including 3 pathogenic variants in 3 families, 3 likely pathogenic in three other families, and 10 variants with uncertain clinical significance for 4 families. Almost all of these variants were identified de novo, except for one family, where the proband has been a compound heterozygous for two variants in the RELN gene. The first case of pathogenic mutation de novo was detected in a girl with agenesis of the corpus callosum. It was a missense mutation DYNC1H1 (NM_001376.5): c.4868G>A (p.Arg1623Gln), which leads to impaired intellectual development in autosomal dominant type 13 (OMIM 614563). The second variant was detected in a boy with corpus callosum agenesis, pontine hypogenesis, pachygyria in the frontal lobes. It was a missense variant MACF1 (ENST00000567887.5): c.21989A>G(p.Asp7330Gly), which leads to lissencephaly 9 with complex brainstem malformation (OMIM 614563). The third variant was found in a girl with epilepsy and impaired myelination of the white matter of the parietal-occipital areas of the cerebral hemispheres. It was a missense variant CDKL5 (NM_001323289.2):c.404-1G>A that leads to developmental and epileptic encephalopathy 2 (OMIM 300672). Conclusions Sixteen candidate variants potentially responsible for mental health were reported in this study. Most of these variants were missense changes in genes. All except one anomalies arisen de novo. Trio-based WES has been shown to be an important step in making a genetic diagnosis if other chromosomal and subchromosomal abnormalities had been excluded. The clinical description of the patient is the most important step for the correct interpretation of WES results, which allows to establish the exact genetic cause of the disease if several variants with unclear clinical significance were previously identified. This study was supported by the Russian Science Foundation, grant 21-65-00017, https://rscf.ru/project/21-65-00017/ Disclosure of Interest None Declared

Introduction aCGH determines pathogenic copy number variations (CNVs) in about 10% of patients with intellectual disability (ID). In another 20% of patients, probably pathogenic CNVs or variants with uncertain clinical significance are detected. It may be variants that do not fully explain the patient’s symptoms, aberrations with reduced penetrance or inherited from healthy parents. The use of a sequencing method for such cases is advisable. Objectives Improvement of diagnosis of intellectual disability. Methods aCGH with 60K Agilent microarrays, qPCR, targeted sequencing, whole exome sequencing (WES). Results Six patients with ID and inherited deletions/duplications detected by aCGH and their parents if available were further examined by sequencing. Four patients had maternal CNVs: (1) del1q41 ( SPATA17, LINC00210, RRP15 ), (2) del7q35 ( TCAF2 , exon 8), (3) dup8p22p21.3 ( PSD3, exons 1-11), and (4) del12p11.1 ( SYT10, exons 1-2). Two patients had paternal CNVs: (5) dup1q44 ( SMYD3 , exons 2-5) and (6) del15q11.2 ( TUBGCP5, CYFIP1, NIPA1, NIPA2, LOC283683 ). The severe phenotype of patient (5) with dup1q44 could not be explained by the paternally inherited disruption of the single SMYD3 gene. WES determined probably pathogenic SNV in the MID1 gene associated with Opitz GBBB syndrome (OMIM 300000), which corresponds better to the patient’s phenotype and is likely to be the cause of the disease. Although del1q41 is included in the region of chromosome 1q41-q42 deletion syndrome (OMIM 612530) the phenotype of the patient (1) is much milder; WES in the patient detected two pathogenic ( MPO, MAN2C1 ) and one probably pathogenic ( ARID1B ) SNVs. In patient (6) with del15q11.2 pat WES detected additional pathogenic SNV in exon 7 of the ARSE gene. In patient (3) with dup8p22p21.3 WES determined two SNVs with uncertain significance in the KIDINS220, FOXG1 genes. No SNVs were detected by WES in patient (2) with del7q35. For patient (4) with del12p11.1 targeted SYT10 sequencing revealed no pathogenic SNVs as well. Conclusions Sometimes aCGH-analysis is sufficient to identify the causes of ID, however, in the case of detection of CNVs with uncertain clinical significance and/or inherited from healthy parents, it may be necessary to further examine the patient using sequencing methods. So, the accurate diagnosis was made by WES for one patient of eight. For another two patients the combination of CNVs and SNPs should be considered. For the last three patients the described aberrations could not explain the phenotype and whole genome sequencing may be the solution.This study was supported by the Russian Science Foundation, grant 21-65-00017, https://rscf.ru/project/21-65-00017/ Disclosure of Interest None Declared

The placenta has a unique hypomethylated genome. Due to this feature of the placenta, there is a potential pos- sibility of using regulatory elements derived from retroviruses and retrotransposons, which are suppressed by DNA methy- lation in the adult body. In addition, there is an abnormal increase in the level of methylation of the LINE -1 retrotransposon in the chorionic trophoblast in spontaneous abortions with both normal karyotype and aneuploidy on different chromo- somes, which may be associated with impaired gene transcription using LINE -1 regulatory elements. To date, 988 genes that can be expressed from alternative LINE -1 promoters have been identified. Using the STRING tool, genes (NUP153 and YWHAB) were selected, the products of which have significant functional relationships with proteins highly expressed in the placenta and involved in trophoblast differentiation. This study aimed to analyze the expression of the NUP153 and YWHAB genes, highly active in the placenta, from canonical and alternative LINE -1 promoters in the germinal part of the placenta of spontaneous and induced abortions. Gene expression analysis was performed using real-time PCR in chorionic villi and extraembryonic mesoderm of induced abortions (n = 10), adult lymphocytes (n = 10), spontaneous abortions with normal karyotype (n = 10), and with the most frequent aneuploidies in the first trimester of pregnancy (trisomy 16 (n = 8) and monosomy X (n = 6)). The LINE -1 methylation index was assessed in the chorionic villi of spontaneous abortions using targeted bisulfite massive parallel sequencing. The level of expression of both genes from canonical promoters was higher in blood lymphocytes than in placental tissues (p < 0.05). However, the expression level of the NUP153 gene from the al- ternative LINE -1 promoter was 17 times higher in chorionic villi and 23 times higher in extraembryonic mesoderm than in lymphocytes (p < 0.05). The expression level of NUP153 and YWHAB from canonical promoters was higher in the group of spontaneous abortions with monosomy X compared to all other groups (p < 0.05). The LINE -1 methylation index negatively correlated with the level of gene expression from both canonical (NUP153 - R = -0.59, YWHAB - R = -0.52, p < 0.05) and alternative LINE -1 promoters (NUP153 - R = -0.46, YWHAB - R = -0.66, p < 0.05). Thus, the observed increase in the LINE -1 methylation index in the placenta of spontaneous abortions is associated with the level of expression of the NUP153 and YWHAB genes not only from alternative but also from canonical promoters, which can subsequently lead to negative con- sequences for normal embryogenesis.

Miscarriage is potentially associated with abnormal epigenetic regulation of genes responsible for the development of the embryo and placenta. The aim of this work was to analyze the methylation level of various subfamilies of the LINE-1 retrotransposon, which makes up about 17% of the entire genome, in chorionic villi of spontaneous abortions of the first trimester of pregnancy with different karyotypes, including the most common aneuploidies. The methylation profile in the LINE-1 retrotransposon promoter was analyzed using targeted bisulfite massive parallel sequencing in chorionic villi of induced abortions ( n = 39), spontaneous abortions with normal karyotype ( n = 173), trisomy 16 ( n = 62) and monosomy X ( n = 46), and peripheral blood lymphocytes of healthy volunteers ( n = 17). The level of methylation of the LINE-1 retrotransposon subfamilies in the control groups of adult lymphocytes and chorionic villi of induced abortions was the highest for evolutionarily young L1HS subfamilies, lower for the more ancient L1PA2 and L1PA3 subfamilies, and the lowest for the even more ancient L1PA4 subfamily. In the groups of spontaneous abortions, an increased level of LINE-1 methylation was observed, and this effect was more pronounced for the older LINE-1 subfamilies. The revealed patterns indicate less control over the older subfamilies of the LINE-1 retrotransposon in the human genome, which can potentially be used as regulatory elements for nearby genes involved in embryonic development. An increase in the level of methylation of such sequences can disrupt the development of the placenta and embryo and make a certain contribution to miscarriage.