Human white blood cells and hair follicles are good sources of mRNA for the pterin carbinolamine dehydratase/dimerization cofactor of HNF1 for mutation detection.

Pterin carbinolamine dehydratase/dimerization cofactor of HNF1 (PCD/DCoH) is a protein that has a dual function. It is a pterin 4alpha-carbinolamine dehydratase that is involved in the regeneration of the cofactor tetrahydrobiopterin during the phenylalanine hydroxylase- catalyzed hydroxylation of phenylalanine. In addition, it is the dimerization cofactor of HNF1 that is able to activate the transcriptional activity of HNF1. Deficiencies in the gene for this dual functional protein result in hyperphenylalaninemia. Here we report for the first time that the PCD/DCoH mRNA is present in human white blood cells and hair follicles. Taking advantage of this finding, a sensitive, rapid and convenient method for screening mutations occurring in the coding region of this gene has been described.