[Chromosomal abnormalities in patients from Obstetrics and Gynaecology hospital]

Chromosomal abnormalities are present in 2-4 % of all newborns, and they cause 20 % of deaths in the first year of life. The estimated prevalence of chromosomal abnormalities is one for each 500-1000 newborns. These abnormalities can be numerical or structural, and they can affect autosomal or sexual chromosomes. They affect from 1 to 3 % of general population, and from 6 to 7 % of individuals with congenital anomalies.

Descriptive study, which included all the registries of cytogenetic analysis (of adults and newborns) made in a genetic laboratory in a period of 14 years. The prevalence of polymorphisms and chromosomal abnormalities in the patients from the Hospital de Ginecoobstetricia 23, Instituto Mexicano del Seguro Social (Monterrey, Nuevo León) was assessed.

Of 4006 cytogenetic studies, 253 (6.3 %) did not show in vitro growth, 2667 (66.5 %) were normal, and 1175 (29.3 %) were abnormal. Of these, 614 (52.2 %) had polymorphisms, and 561 (47.7 %) structural or numerical chromosomal abnormalities. In regards to these chromosomopathies (561), trisomy 21 was observed in 429 (36.5 %); Turner's syndrome, in 84 (7.1 %); trisomy 18, in 57 (4.8 %); and trisomy 13, in 32 (2.7 %). With G-band technique, we found 93 % of in vitro cell growth.

Of these studies, 55 % was performed due to non-numerical abnormalities; 14.4 %, due to structural abnormalities; and the rest, due to polymorphisms.