Length variability in α-synuclein gene predisposes to Parkinson's disease

The aetiology of Parkinson's disease is largely unknown, but genetic factors may be implicated. The most promising association of a gene with susceptibility for Parkinson's disease seems to be that of the α-synuclein gene, but previous studies gave conflicting results.

A collaboration of 18 teams of researchers worldwide analysed published and unpublished individual data for more than 5000 people. They found that variability in the length of a dinucleotide repeat sequence (REP1) in the promoter of the α-synuclein gene was associated with susceptibility to Parkinson's disease: the 263 base pair allele conveyed an increased risk of developing the disease, whereas the 259 base pair allele seemed to be protective. However, the gene variants did not seem to modify the age of disease onset.

The gene codes for the α-synuclein protein, which is abnormally aggregated in the neurones of people with Parkinson's disease, although only about 1% of people with the disease have a mutated α-synuclein gene. The α-synuclein protein is also the major compound of Lewy bodies, the pathohistological marker of Parkinson's disease. If overexpression of the α-synuclein gene was a common underlying pathophysiological mechanism in people with the disease, this would offer opportunities for new drugs targeted at reducing expression of the gene. As yet, however, there is no robust evidence for this. Large longitudinal studies are needed to assess whether the gene has a modifying effect on the course of the disease.

Adherence to antiretroviral treatment is high in Africa

Concerns raised over the ability of people infected with HIV in sub-Saharan Africa to adhere to antiretroviral treatment seem to contribute to delayed access to treatment. A recent meta-analysis showed that these concerns are unjustified.

A comprehensive search for available data on adherence rates found 31 studies (17 573 patients) from North America and 27 studies (12 116 patients) …