Functional characterisation of a complex mutation in the α(1,4)galactosyltransferase gene in Taiwanese individuals with p phenotype.

Individuals with p phenotype lack P1, P(k) and P antigens on red blood cells, presumably as a result of deficiency in the enzyme α(1,4)galactosyltransferase (A4GALT). The aim of this study was to explore the molecular background of a Taiwanese family with p phenotype.,Blood samples from two p siblings and seven family members were investigated. The coding region of the A4GALT gene was analysed by polymerase chain reaction and direct sequencing. The wild- and mutant-complementary DNAs (cDNAs) of A4GALT were cloned into an expression vector and transfected to Chinese hamster ovary (CHO) cells. P(k) expression on the transfected cells was analysed by flow cytometry and the activities of A4GALT were measured by high-performance liquid chromatography.,The two individuals with p phenotype were homozygous for the complex mutation, which was caused by a combined deletion and insertion between nt 418 and 428. No expression of P(k) and no enzyme activity were observed in cells transfected with the mutant construct.,The first case of p phenotype in Taiwan was caused by a non-functional allele resulting from a homozygous complex mutation of A4GALT gene.