Relationship of human heterochromatin and congenital malformations

Abstract

Aim. The variability of centromeric heterochromatin of the chromosome pairs 1,9 and 16 was studied in material pro- vided by the Cytogenetic Counselling Centre.

Materials and methods. The size of bands 1q12, 9q12 and 16q11 was classified as normal, larger, very large, narrow and pericentric inversion. The karyotypes under study were divided into four groups: (I) from persons with abnormal karyotype and abnor-mal phenotype, ( I I ) from persons with abnormal phenotype and normal karyotype, (III) from healthy nearest relatives (parents and sibs) of persons with abnormal phenotype and karyotype, (I V ) from normal healthy persons with normal phenotype and karyotype without any congenital malformations in the family history.

Results. A different variability of centromeric hetero-chromatin of chromosomes 1 , 9 and 16 was observed. Quite a low variability was found in chromosome 16, while chromosomes 9 and 1 showed a high degree of variability, which was more accentuated in chromosome 9 than in chromo-some 1 .

Conclusions. In all four groups there was a similar pattern of variability with the only exception in the group of nearest relatives of children with abnormal phenotype and karyotype where an unusually narrow band 1q12 was more fre- quently detected.