Phenotypic and genetic analysis of a compound heterozygote for dys- and hypoprothrombinaemia

We studied a 2-year-old boy with a phenotype of combined hypo- and dysprothrombinaemia. Sequencing of polymerase-chain-reaction-amplified genomic DNA revealed three different mutations in heterozygosity, a G to A transition at position 7312, resulting in the replacement of arginine 271 by histidine, an A to G transition at position 20058, resulting in the replacement of histidine 562 by arginine, and a 2-bp deletion at 20062-20063, causing a frameshift and a premature stop codon in exon 14. The first two mutations are compatible with the dysprothrombinaemia phenotype, whereas the small deletion is thought to be the cause of hypoprothrombinaemia.