Nondisjunction of chromosome 21.
Chromosome heteromorphisms and restriction fragment length polymorphisms were used to study the origin of the extra chromosome in 54 trisomy 21 conceptuses. The parental origin was determined in 43 cases, with 39 (91%) being maternally and 4 (9%) parentally derived. Analysis of recombination demonstrated the presence of one or two cross-overs in most cases for which sufficient information was available, suggesting that failure to pair/exchange at meiosis I is relatively unimportant in the genesis of trisomy 21.
Takaesu
N
N
Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322.
Jacobs
P A
PA
Cockwell
A
A
Blackston
R D
RD
Freeman
S
S
Nuccio
J
J
Kurnit
D M
DM
Uchida
I
I
Freeman
V
V
Hassold
T
T
D000328:Adult; D002891:Chromosomes, Human, Pair 21; D003434:Crossing Over, Genetic; D004314:Down Syndrome / Q000235:genetics*; D005260:Female; D006801:Humans; D007621:Karyotyping; D008297:Male; D008423:Maternal Age; D008540:Meiosis; D008875:Middle Aged; D009630:Nondisjunction, Genetic; D010331:Paternal Age; D012150:Polymorphism, Restriction Fragment Length; D018566:Pregnancy, High-Risk; D011995:Recombination, Genetic