THE FREQUENCY AND PATTERN OF ACROCENTRIC CHROMOSOME ASSOCIATION IN PARENTS OF DOWN-SYNDROME CHILDREN AND CONTROLS

We have studied the frequency and pattern of acrocentric chromosome as sociation (ACA)in parents of children with Down syndrome (DS) who cont ributed or did not contribute an extra chromosome 21 to their offsprin g. The findings were compared with those for age-matched controls. The acrocentric chromosome association index (ACAI) calculated by quantit ating combined the frequencies of D and G group chromosomes in differe nt types of associations. There were significant (P < 0.05) increases in ACA index (ACAI) and in the percentage of association of G group ch romosome in mothers who contributed the extra chromosome. These result s strongly support the view that ACA are a potential risk factor for n on-disjunction, resulting in the development of aneuploidic karyotypes and trisomy 21 in DS offspring. (C) 1998 Chapman & Hall Ltd.