The p53 pathway and natural selection
The expression of p53 is regulated by a number of proteins, and one of its main inhibitors is MDM2. Researchers have predicted that alleles of the genes may be under selective pressures. Shi and colleagues report that the p53 allele has undergone selective pressure due to changes in winter temperature, but not in response to UV exposure. In contrast, the MDM2 variant showed signs of selection only due to UV exposure.

The XQTL test in family-based designs
Methods of testing for association with markers on the X-chromosome differ from those dealing with autosomal loci because the X-chromosome undergoes differential inheritance in males versus females and is subject to dosage compensation. Here, Zhang et al. develop a test that identifies X-linked QTL by using family samples.

DPP6 in IVF
Idiopathic ventricular fibrillation (IVF) is currently diagnosed only after the occurrence of a sudden cardiac death or an aborted sudden cardiac death. The presence of a family history of IVF indicates a genetic component to this condition. Here, Alders et al. identify a conserved haplotype on 7q36 encompassing DPP6 in IVF families, providing hope for earlier diagnosis.

A duplication within a BMP2 regulatory element
One type of brachydactyly, BDA2, is characterized by shortening of the middle phalanges of the second and fifth finger. Here, Dathe and colleagues study two families with a variable but penetrant BDA2 phenotype. Genome-wide linkage analysis identifies a locus on 20p with the promising candidate BMP2, but initial sequencing efforts fail to identify any obvious mutations. The authors then examine the genomic region surrounding the BMP2 coding sequence and find small duplications about 110 kb downstream in both families.

Genome-wide linkage screen of familial PD
Genome-wide linkage studies (GWLS) can be a powerful technique used to uncover regions of the genome associated with a certain trait or disorder. Here, Gao et al. conduct a GWLS to detect genomic regions that associate with Parkinson disease (PD). Their findings indicate that a region on chromosome 18 containing 76 annotated genes and another locus on chromosome 3 containing 90 genes are associated with PD.