Endocrine Abstracts

Goal: Identification of latent mosaicism and determination of a parental origin of an X chromosome in TS patients in Uzbek population.

Methods: Molecular genetic studies are carried out in 35 patients with TS (26 with monosomy and nine with mosaicism) at the age of 7–16 and their parents with a set of DIATOMTMDNA prep 200 reagents. DNA amplification was performed in Applied Biosystems thermocyclers. PCR products were subjected to electrophoresis on 12% acrylamide bis-acrylamide gel (29:1) with subsequent DNA staining with ethidium bromide and visualization by a BioDocAnalyze (Biometra) system.

Results: Three X-linked markers (DMD 49, AR and DX1283E) were studied on the basis of their high level of heterozygosis (varying from 88.6 to 93.3%), a number of alleles (11–19) and localisation both on a short and long X chromosome arm. The results obtained confirm that the use of a set of these primers (DMD 49, AR and DX1283E) will allow enhancing a probability of obtaining an informative marker and detection of latent X-mosaicism. Monozygosity on all three markers indicates the presence of only one X chromosome that in female patients will correspond to true monosomy (X0). Heterozygosis of one marker suggests on the presence of an additional second X chromosome or a part of an X chromosome which is observed both in 46XX karyotype (healthy) and in mosaic variants of chromosomal anomalies (45X0–46XX and 45X0–46XY).

Conclusions: A comparative analysis of polymorphic markers in TS patients and their parents enable us to establish the origin of an X chromosome and determine in gametogenesis of which parents meiotic impairment occurred. Identification of mosaicism in Turner syndrome is very important from the viewpoint of setting correlations between a phenotype and karyotype.