X-linked hypophosphataemia in South Africa

To investigate the pattern of clinical presentation in a series of South African subjects with X-linked hypophosphataemia (XLH) with particular reference to ethnic differences in presentation and inheritance, and to determine the perceptions and psychosocial problems associated with the disease.

The clinical details of 50 subjects were collected from their records as well as from examining those currently attending the clinics held at Chris Hani Baragwanath Hospital and the National Health Laboratory Services in Johannesburg. There were 17 males and 33 females in the study. The psychosocial part of the study involved interviews with 20 parents and 7 subjects (aged 16 years or more).

Thirty-one of the subjects were black, 17 white and 2 Indian. The mean age of clinical onset was 2.02 years (range 0.25 - 10 years). Fifty-four per cent of the cases were apparently sporadic. The prevalence of sporadic mutations was 64% among the black subjects and 41% among the white subjects. No differences were found in either clinical or biochemical presentation between genders or ethnic groups, despite an apparently higher sporadic presentation in the black children. The study also showed that this disorder had not only affected family life but also the lives of the subjects and their interpersonal relationships. The hereditary nature of the condition was not clear to most parents even after having attended the clinic for many years.

South African subjects with XLH have similar features to those reported in other studies but there is a higher prevalence of sporadic mutations in the black subjects. Better counselling services are needed to improve the understanding of this condition among parents of affected children.