Gene-rich chromosome regions and autosomal trisomy

Abstract

Cases of autosomal trisomy and trisomy mosaicism among liveborn infants are reviewed, and a second case of chromosome 3 trisomy mosaicism is described. The occurrence of autosomal trisomy for a particular chromosome is in general negatively correlated with the number of genes which have been localized to that chromosome. It is also positively related to the Q-brightness of the chromosome, which reflects its content of intercalary heterochromatin. Furthermore there are significantly fewer autosomal trisomics for chromosomes which contain hot spots for mitotic chiasmata in Bloom syndrome (chromosomes 1, 3, 6, 11, 12, 17, 19, and 22), compared with similar-sized control chromosomes 2, 4, 7, 9, 10, 18, 20, and 21. This is interpreted as further evidence for the gene richness of the hot spots which, being active, are extended in interphase and are therefore available for mitotic crossing over. The gene richness of these short Q-dark regions is also borne out by the scarcity of trisomic abortions for the chromosomes involved (the embryo dies before the abortion is recognized) and by the higher number of genes localized to these chromosomes compared with the control chromosomes.

Rare Trisomy Mosaicism Diagnosed in Amniocytes, Involving an Autosome Other Than Chromosomes 13, 18, 20, and 21: Karyotype/Phenotype Correlations

“…One adult was reported to have severe mental retardation, short stature, and dysmorphic facies (Kuhn et al, 1987). One adult had short stature, coloboma, hip dislocation, and Bartter syndrome (DeKeyser et al, 1988).…”

Numerical and structural chromosomal abnormalities detected in human sperm with a combination of multicolor FISH assays

“…These chromosomes have varying influences as trisomies during development. Trisomy 1 is associated with very early fetal death [Kuhn et al, 1987]; the paternal contribution to trisomy 1 is not known. Trisomy 16 is the most common form of trisomy found among spontaneously aborted fetuses [21.5%;Eiben et al, 1990].…”

Effect of paternal age on the frequency of cytogenetic abnormalities in human spermatozoa

“…Watt et al (1987) demonstrated trisomy 1 in an eight-cell embryo. These findings have led to the assumption that trisomy 1 does occur, but is lethal very early in fetal development, and that there has been no paternal contribution for trisomy 1 known until now (Kuhn et al, 1987). Trisomy 16 also is typically of maternal origin, and only a few paternally derived cases have been reported (Hassold et al, , 1996.…”