Genetic aspects of the obstructive sleep apnoea/hypopnoea syndrome--is there a common link with obesity?

Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is the third most common respiratory condition after asthma and chronic obstructive airway disease affecting approximately 2-4% of the middle-aged population. OSAHS has a hereditary component but owing to difficulties with phenotyping, its genetic basis has been difficult to elucidate. Despite this, limited progress has been made in considering the genetic basis of the 'intermediate phenotypes' of OSAHS such as craniofacial structure and upper airway control. Obesity is a risk factor for the development of OSAHS. The genetics of obesity are complex, but advances have been made recently using genome-wide association studies. Some authors postulate that OSAHS and common obesity share many pathophysiological pathways. However, the genes underpinning the development of sleep-disordered breathing and obesity are likely to be different, despite phenotypes that appear to overlap and influence each other's expression. This paper focuses on human studies over-viewing the most recent work in the area and includes a brief discussion on methods of genetic studies.