[Risk of chromosomally unbalanced progeny in prenatal diagnoses of reciprocal translocation carrier].
To obtain new criteria for presuming the existence of chromosomally unbalanced progeny in reciprocal translocation carrier couples, the obstetrical histories of 57 couples were analysed. The chromosomally unbalanced progeny who had been prenatally or postnatally diagnosed were mainly partial trisomies. In contrast with partial trisomies, there were only a few cases of partial monosomies and there were only two cases of chromosomal imbalance derived from 3:1 segregation in gametogenesis. Moreover, the percentage of haploid autosome length (%HAL) of the maternal carriers whose progeny had suffered from chromosomal imbalance was significantly smaller than those of the maternal carriers who had not had progeny with chromosomal imbalance. Based on these results, the following criteria were obtained: 1) Partial trisomies tend to be maintained in pregnancy but partial monosomies do not; Most chromosomally unbalanced zygotes which were induced by 3:1 segregated gametes tend to be spontaneously selected in early pregnancy; 3) When interchanged segments of chromosomes are small in maternal reciprocal translocation carriers, chromosomally unbalanced fetuses tend to be maintained in pregnancy.
Takeyama
Y
Y
Department of Obstetrics and Gynecology, Tohoku University School of Medicine, Sendai.
Uehara
S
S
Kobayashi
M
M
Kimura
Y
Y
Suzuki
N
N
Ami
M
M
Ohta
T
T
Suzuki
T
T
Okamura
K
K
Takabayashi
T
T
D005260:Female; D005817:Genetic Counseling; D006579:Heterozygote; D006801:Humans; D008297:Male; D016742:Preconception Care; D018570:Risk Assessment; D014178:Translocation, Genetic; D014314:Trisomy