A low rate of trisomy 21 in twin-pregnancies: a cytogenetics retrospective study of 278 cases.

From January 1st 1990 until December 31st 2001, we collected 19686 prenatal diagnosis (on amniocentesis and chorius villus sampling). Five hundred twelve samples (2.6%) concerned 278 twin pregnancies.

Major decrease in the incidence of trisomy 21 at birth in south Belgium: mass impact of triple test?

In South Belgium (Wallonia), the 'triple test' was introduced in 1990-1991, and is nowadays a widely accepted screening method for assessment of trisomy 21 risk in pregnancy. The 'triple test' is not regulated and can be freely performed by any biomedical lab, making epidemiological data unavailable. By contrast, cytogenetic investigations are limited to a few genetic centres, and accurate statistics can be easily built from their files.

Inv(12)(q15q24): a nonrandom change associated with myelodysplasia?

A patient with refractory anemia and a paracentric inversion of chromosome 12, inv(12)(q15q24), is described. This is the second reported case with this chromosome anomaly, suggesting that this rearrangement is a rare but nonrandom change associated with myelodysplastic syndromes.

Deletion of the 5'-ABL region: a recurrent anomaly detected by fluorescence in situ hybridization in about 10% of Philadelphia-positive chronic myeloid leukaemia patients.

Inclusion of the BCR-ABL ES probe in routine cytogenetics led to the identification of a subgroup of Philadelphia positive (Ph+) chronic myeloid leukaemia patients characterized by a 5'-ABL deletion. This anomaly was observed in 5/51 cases (9.8%).