Registration of Down syndrome in the Medical Birth Registry of Norway: validity and time trends.

Objective: To validate Down syndrome registration in the Medical Birth Registry of Norway (MBRN), 2001-2005, and study time trends and geographical differences in Down syndrome prevalence,1967-2005.

Design/setting: Population-based cohort study, Norway.

Population: 2.

Follow-up of a girl with cleft lip and palate and multiple malformations: trisomy 20 mosaicism.

We describe a 16(1/2) -year-old girl with multiple anomalies including cleft lip and palate and a normal karyotype in blood lymphocytes. Because of hyperpigmention along the lines of Blaschko, her karyotype in skin fibroblasts was examined, which showed mosaicism for trisomy 20. This is the first report to our knowledge of this karyotype where hyperpigmentation and facial clefting occurred together.

An excess of chromosome 1 breakpoints in male infertility.

In a search for potential infertility loci, which might be revealed by clustering of chromosomal breakpoints, we compiled 464 infertile males with a balanced rearrangement from Mendelian Cytogenetics Network database (MCNdb) and compared their karyotypes with those of a Danish nation-wide cohort. We excluded Robertsonian translocations, rearrangements involving sex chromosomes and common variants. We identified 10 autosomal bands, five of which were on chromosome 1, with a large excess of breakpoints in the infertility group.