Evidence for a correlation between late replication and autosomal gene inactivation in a familial translocation t(X;21).
A familial translocation t(X;21)(q2700;q11) is studied. A girl, trisomic for almost all the chromosome 21, has a mildly abnormal phenotype. A second girl, phenotypically abnormal, is monosomic for the juxtacentromeric region of chromosome 21 only. A comparison of the replication pattern and of the activity of superoxide dismutase (gene located on chromosome 21) shows a clear correlation between late replication, gene inactivation and phenotype expression of chromsome 21.
D002904:Chromosomes, Human, 21-22 and Y; D004261:DNA Replication; D004314:Down Syndrome / Q000235:genetics; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008607:Intellectual Disability / Q000235:genetics; D008297:Male; D010375:Pedigree; D010641:Phenotype; D012730:Sex Chromosomes; D014178:Translocation, Genetic; D014960:X Chromosome