A group of 46 European patients with mucopolysaccharidosis type I (MPS I) was screened for mutations of the alpha-L-iduronidase gene. The 2 common nonsense mutations, W402X and Q70X, were identified in, respectively, 37% and 35% of mutant alleles. Considerable differences were seen in the frequency of these 2 mutations in patients from North Europe (Norway and Finland) and other European countries (mainly The Netherlands and Germany). In Scandinavia, W402X and Q70X account for 17% and 62% of the MPS I alleles, respectively, while in other European countries W402X is about 2.5 times more frequent (48%) than Q70X (19%). Eight novel mutations are described including 4 missense mutations, 1 nonsense mutation, 1 insertion of 2 base pairs, and 2 deletions of 1 and 12 base pairs.

Mutations of the iduronate-2-sulfatase gene were identified in 16 patients with mucopolysaccharidosis type II (Hunter syndrome). Together with another 10 cases reported by us earlier it emerges that about 20% of the patients have deletions of the whole gene or other major structural alterations. One, two or three base pair deletions are found in about 23% of the cases while the remaining about 57% carry point mutations predicting amino acid replacement, premature termination of translation, or aberrant splicing. Molecular analysis of mRNA in splice site mutants showed that these latter defects frequently resulted in use of cryptic splice sites in exons or introns. 62% of the small deletions and point mutations have occurred in 3 of the 9 iduronate-2-sulfatase gene exons. Knowledge of the primary genetic defect allows fast and reliable carrier detection and prenatal diagnosis as well as insight into the relationship between genotype and phenotype.

Among 639 spontaneous abortions between the 8th and 14th week of gestation 342 (53.5%) revealed an abnormal karyotype. While the rate of trisomies distinctly increased with advancing maternal age, a decrease in the rate of 45,X conceptuses and polyploidies was observed among abortions from older women. The overall relation of XXXX:XXYY among the tetraploidies was 14:11 and that of XXX:XXY:XYY among the triploidies was 26:36:1. However, when the latter was related to maternal age, a reversal of the XXX:XXY ratio of 1:2 in the younger to 2:1 in the older age groups became evident. Furthermore a decrease in the rate of "paternally" derived partial hydatidiform moles was found among the triploid abortion specimens from older women. From these observations we conclude that digyny plays a major role in the origin of triploidy in the increased maternal age groups, while diandry related to immaturity of oocytes and impairment of oocyte cortical function is more frequent in triploid abortions from younger women.

“Jumping translocation” (jt) refers to a rare type of chromosome mosaic, in which the same portion of a (donor) chomosome is translocated to different (recipient) chromosome sites. It have mainly been observed in lymphocyte cultures of patients with hematologic malignancies. We report a phenotypically normal female carrying a mosaic of two cell lines with the Xq26‐qter segment translocated to the short arm of chromosomes 15 or 21 in peripheral blood lymphocytes. In skin fibroblasts, only the X/21 translocation was detected. We speculate that recombination between homologous repetitive sequences on non‐homologous human acrocentrics may be the cause of such chromosomal rearrangements.

Die Indikationsstellung zur invasiven pränatalen Diagnostik (PND) fetaler chromosomaler Störungen hat sich im letzten Jahrzehnt verändert. Die Altersindikation (Alter der Schwangeren ≥ 35 Jahren) verliert zugunsten einer individuellen Indikationsstellung unter Berücksichtigung des maternalen Alters und der detaillierten Sonographie inklusive fetaler Echokardiographie zunehmend an Bedeutung. Durch den Einsatz von hochauflösenden Ultraschallsonden und der Vaginalsonographie können Auffälligkeiten beim Feten (z. B. strukturelle Fehlbildungen, wie Omphalozele, Herzfehler, ZNS-Fehlbildungen, Megazystis und Extremitätenfehlbildungen, und "Marker", wie verdickte Nackentransparenz, Hygroma colli und Hydrops fetalis), die mit einer chromosomalen Fehlverteilung oder auch nicht chromosomal bedingten Syndromen assoziiert sind, häufig bereits im 1. Trimenon erkannt werden. Die frühe Diagnose solcher struktureller Fehlbildungen und Marker ermöglicht es, den Paaren nach individueller, ausführlicher Beratung eine invasive Diagnostik zur Bestimmung des fetalen Karyotyps anzubieten. Die Entwicklungen der nicht invasiven Verfahren der pränatalen Diagnostik resultierten in einem Rückgang der invasiven pränatalen diagnostischen Eingriffe (Amniozentese [AC], Chorionzottenbiopsie [CVS]) bei gleichzeitigem Anstieg des Anteils von auffälligen Chromosomenbefunden in den letzten 15 Jahren im Bereich der