Discovery of a novel multilocus DNA polymorphism [DNF24]

Recent human-specific spreading of a subtelomeric domain

The recent spreading of a subtelomeric region at nine different human chromosome ends was characterized by a combination of segregation analyses, physical mapping, junction cloning, and FISH investigations. The events occurred very recently in human genome evolution as demonstrated by sequence analysis of different alleles and the single location of the ancestral site at chromosome 17qter in chimpanzee and orangutan. The domain successfully colonized most 1p, 5q, and 6q chromosome ends and is also present at a significant frequency of 6p, 7p, 8p, 11p, 15q, and 19p ends. On 6qter, the transposed domain is immediately distal to the highly conserved, single-copy gene PDCD2.

Identical twin discordance for the Brachmann-de Lange syndrome revisited

The only known twin pair evidently discordantly affected for the BDLS (Brachmann-de Lange syndrome) and who had been considered monozygotic (MZ) based on blood analysis remained a problem because biological zygosity determination needed further typing. In this report we review the clinical findings of this pair of twins at the age of 20. The use of DNA fingerprinting with three multilocus probes, F10, DNF24, and 33.6, allowed us to present evidence of monozygosity with a high degree of certainty. The significance of this confirmation of discordance in determining the cause of BDLS is discussed. Intensive comparative genomic studies of the discordant twin sisters may be useful to unravel the molecular genetics of this enigmatic pattern of malformation.

Paternity testing in the DNA era

Paternity can be efficiently and effectively tested using multi-allelic variable number of tandem repeat (VNTR) polymorphisms. This can be achieved by using multilocus DNA fingerprinting probes or batteries of single-locus minisatellite probes, or by PCR testing of sets of minisatellite and microsatellite loci. Although some problems of statistics and population genetics remain to be overcome, the informativeness of these hypervariable loci is so high that paternity disputes can be resolved with certainty in virtually every case.