The molecular basis of transferase galactosaemia in South African negroids

Transferase galactosaemia is an autosomal recessively inherited disorder ca used by a deficiency of galactose-l-phosphate uridyltransferase (GALT). Man ifestations include jaundice, vomiting, cataracts, mental retardation, spee ch abnormalities and poor growth. The GALT gene has been mapped and sequenc ed. The S135L mutation accounts for approximately 48% of galactosaemia alle les in African Americans and has been found to account for about 91% of gal actosaemia alleles in negroid South African patients which suggested that t he mutation had an African origin. We have calculated the S135L allele freq uency (+/-1SE) in a sample of healthy unrelated negroid South Africans to b e 0.0067 (+/-0.0024). The S135L mutation was also detected in negroid popul ations from other regions of Africa confirming its African origin.