A case of mental retardation in a subject with slight signs of deformity is reported. Q band analysis of the karyotype showed extension of band 2 of area 1 of the long arm of chromosome No. 9. Examination of this feature after staining with acridine orange made it clear that this extension was not due to spontaneous DNA denaturation, but was caused by local duplication of chromatin. It is pointed out that such chromatin must be considered as constitutive heterochromatin.
|Number of pages||5|
|Publication status||Published - 1975|
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health