Abstract
Down syndrome (DS) is the most common disease due to an autosomal aneuploidy in live born children and also the major known genetic cause of mental retardation. The risk of a DS pregnancy increases substantially with increasing maternal age. However, several women aged less than 35 years at conception have a child with DS. The micronucleus (MN) assay can identify chromosome breakage or chromosome malsegregation and is an ideal biomarker to investigate genomic instability. The aim of the present study was to determine the frequency of peripheral lymphocytes with MN in the parents of DS individuals. The subjects were 17 couples, 1 father and 9 mothers, and 24 couples who had at least one healthy child formed the control group. For each individual we evaluated the frequency of binucleated micronucleated lymphocytes (BNMN%) as number of binucleated lymphocytes containing one or more MN per 1000 binucleated cells. The mean age of DS parents and controls was 32.6 and 29.8 years, respectively. The frequency of MN in DS parents was significantly higher compared to controls. The higher frequency of MN in DS parents suggests a higher predisposition of DS parents to aneuploidy events in this sample.
Highlights
Down syndrome (DS) is the most common disease due to an autosomal aneuploidy in live born children and the major known genetic cause of mental retardation
An increased meiotic nondisjunction in parents of trisomic children and in couples with recurrent abortions has been demonstrated, supporting the hypothesis that errors of chromosome segregation may be due to spindle defects, to chromosome breakage, or to abnormal chromosome associations [7,8,9]
Two thousand binucleated cells were examined for each individual and we evaluated the frequency of binucleated micronucleated lymphocytes (BNMN%) as the number of binucleated lymphocytes containing one or more MN per 1000 binucleated cells
Summary
Down syndrome (DS) is the most common disease due to an autosomal aneuploidy in live born children and the major known genetic cause of mental retardation. The risk of a DS pregnancy is a function of maternal age, and after age 35 years it increases substantially with increasing maternal age [3,4]. Women aged less than 35 years at conception have had children with DS, suggesting a predisposition to early abnormal chromosome segregation events in these women [5,6]. An increased meiotic nondisjunction in parents of trisomic children and in couples with recurrent abortions has been demonstrated, supporting the hypothesis that errors of chromosome segregation may be due to spindle defects, to chromosome breakage, or to abnormal chromosome associations [7,8,9].
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