Genetic forms of developmental delay and intellectual disability in the practice of the medical genetic consultation of Research Centre for Medical Genetics

Developmental delay (DD) and intellectual disability (ID) are frequent reasons for referring patients for medical genetic counseling. A significant increase in the number of nosological forms of monogenic and chromosomal diseases among patients with DD or ID in medical genetic consultation of Bochkov Research Centre for Medical Genetics in recent years reflects an increase in its effectiveness in diagnosing this pathology. Purpose of the research: 1. To estimate the proportion of clinically and/or laboratory-confirmed chromosomal, monogenic, and genomic imprinting disorders diagnosed in patients with DD or ID consulted by geneticists from the consultation and scientific consulting departments of the Bochkov Research Centre for Medical Genetics in 2006, 2007, 2016, and the first half of 2017. 2. Determination of the effectiveness of different diagnostic methods of genetic forms DD and ID. 3. Calculation of segregation frequency to estimate the contribution of monogenic forms with autosomal recessive and X-linked recessive types of inheritance among undifferentiated cases of DD and ID. The sampling for the analysis included 2350 patients with DD or ID of varying severity, as well as patients with a diagnosis suggesting the development of DD or ID as they mature, consulted by geneticists from the consultation and scientific consulting departments of the Bochkov Research Centre for Medical Genetics in 2006, 2007, 2016, and the first half of 2017. During the research period (2006, 2007, 2016, and the first half of 2017), there was a decreasing trend in the proportion of chromosomal pathology among all patients of the sampling. Within the group of patients with DD or ID with chromosomal pathology, a significant increase in the proportion of structural chromosomal pathology and a decrease in the proportion of diseases caused by changes in the number of chromosomes is noted over time. The proportion of monogenic forms remains practically unchanged during the study period. Within this group, there is some increase in the share of AD pathology. The proportion of patients with DD or ID caused by genomic imprinting disorders varies significantly in the years studied, with a tendency to decrease over time. The proportion of only clinically identified syndromes without laboratory confirmation decreases significantly during the study period. The maximum diagnostic efficiency among laboratory genetic methods has been shown for microsatellite analysis, MLPA, chromosomal microarray analysis (CMA) and next generation sequencing (NGS).

developmental delay, intellectual disability, chromosomal diseases, monogenic diseases, genomic imprinting disorders, diagnostic efficiency, segregation analysis, chromosomal microarray analysis, next generation sequencing

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