ABSTRACT
Using DAPI staining after pretreatment with distamycin A we detected a familial deficiency of chromosome 16 heterochromatin. A distinct positively staining band, however, was seen after C-banding. Thus, by using these different heterochromatin staining methods, heterogeneity of the constitutive heterochromatin in the centromeric region of human chromosome 16 was indicated. The same C-banding procedure was also applied to a previously described familial deficiency of chromosome 9 heterochromatin evidenced using distamycin A/DAPI staining and G 11 staining (Buys et al., 1979). In this case a C-band appeared to be virtually absent on the relevant chromosome. These staining methods may be valuable tools in the study of chromosome polymorphisms.
Subject(s)
Chromosome Banding/methods , Chromosomes, Human, 16-18/analysis , Heterochromatin , Azure Stains , Chromosomes, Human, 6-12 and X/analysis , DNA, Satellite/analysis , Distamycins , Female , Humans , Indoles , Male , Polymorphism, GeneticABSTRACT
In cultured amniotic fluid cells a mediocentric chromosome 9 appeared to be completely deficient in constitutive heterochromatin when stained with distamycin A and DAPI. In addition, this deficient chromosome was found in a blood cell culture from the father. Both the father and the child after birth were phenotypically normal. Evidently, a considerable heterozygotic deficit of chromosome 9 heterochromatin can be tolerated without affecting the phenotype. The heterochromatin defect was also shown by G11-staining. Distamycin A-DAPI staining is highly reproducible and is recommended as a fluorescent alternative to often less successful G11-methods for the detection of heteromorphism of chromosome 9.
Subject(s)
Chromosomes, Human, 6-12 and X , Heterochromatin , Adult , Amniotic Fluid/cytology , Female , Heterozygote , Humans , Infant, Newborn , Karyotyping , Male , Phenotype , Pregnancy , Staining and LabelingABSTRACT
A translocation of heterochromatic material, brightly fluorescent after actinomycin D-DAPI staining, to the short arm of chromosome 14 was prenatally detected during cytogenetic examination of cells obtained by amniocentesis on the indication of advanced maternal age. Besides this abnormal chromosome, 43 autosomes and two X chromosomes were present. Silver staining made clear that an active nucleolus-organizing region was included in the translocation product. Both the intense fluorescence and the size of the translocated extra heterochromatic block were indicative of a Yq origin. Upon cytogenetic investigation of the parents, the mother appeared to carry the same t(Y;14) chromosome. Therefore, we expected a normal girl to be born. This was confirmed after birth.
