Mutational analyses in four Japanese families with X-linked liver phosphorylase kinase deficiency type 1

We analysed the gene of the human alpha-subunit of liver phosphorylase kina se (PHKA2) in four Japanese families with X-linked liver phosphorylase kina se deficiency type 1 by RT-PCR followed by PCR-single-strand conformation p olymorphism and direct DNA sequencing. In this study, two novel mutations ( Y116D and 2675A --> G) and one mutation previously reported (P1205L) were i dentified, revealing molecular heterogeneity in Japanese patients. Consider ing the dissimilarity in phenotype among our patients even with an identica l mutation in the PHKA2 gene, it seems that each genetic deficiency in this gene may not be the only factor to determine the clinical heterogeneity in this disease.