Search

We attempted to demonstrate a relation between a loss of replication control, centromere dysfunction, and predisposition to non-disjunction. Couples with a Down syndrome offspring were the high-risk probands. One-color FISH (fluorescent in-situ hybridization) was applied to interphase nuclei (lymphocytes). Replication pattern of two pairs of alleles, RB-1 and 21q22, were studied, and the rate of aneuploidy was estimated using two alpha-satellite probes of chromosomes 8 and 18. Our results suggest the existence of an association between replication timing and the rate of non-disjunction. A higher rate of allele asynchrony and aneuploidy was found in older women and in mothers of a Down syndrome offspring. These findings may reflect a predisposition for meiotic non-disjunction in these women.

Johanson-Blizzard syndrome is a rare autosomal recessive disorder characterized by aplasia of alae nasi, pancreatic insufficiency, aplasia cutis, anorectal anomalies and postnatal growth restriction. In this case report, we describe the prenatal sonographic findings of Johanson-Blizzard syndrome in a 21-week pregnancy of a consanguineous couple. Sonographic findings of aplastic alae nasi (beak-like nose) and dilated sigmoid colon led to the prenatal diagnosis. This is the first report of the prenatal sonographic diagnosis of Johanson-Blizzard syndrome.

We attempted to demonstrate a relation between a loss of replication control, centromere dysfunction, and predisposition to non-disjunction. Couples with a Down syndrome offspring were the high-risk probands. One-color FISH (fluorescent in-situ hybridization) was applied to interphase nuclei (lymphocytes). Replication pattern of two pairs of alleles, RB-1 and 21q22, were studied, and the rate of aneuploidy was estimated using two alpha-satellite probes of chromosomes 8 and 18. Our results suggest the existence of an association between replication timing and the rate of non-disjunction. A higher rate of allele asynchrony and aneuploidy was found in older women and in mothers of a Down syndrome offspring. These findings may reflect a predisposition for meiotic non-disjunction in these women.

A 31 years old women underwent amniocentesis because of increased risk for Down syndrome on biochemical screen. Her previous pregnancy ended in a spontaneous abortion. The Karyotype was 46, XY/47, XY, +21, inv(9) with a mosaicism rate of 45%. The husband, which was known to have oligo-terato-asteno-spermia on semen analysis, had a karyotype 46, XY, inv(9)(q11; 13)9qh+. Mono and dual color FISH was applied to his sperm as well as to sperm of normal controls, using centromer probes for 8, 9, 18, 21, X and Y. In this man with inv9 and 9qh+ the rate of disomy was significantly higher then in normal controls for all probes tested (p