Severe FVII deficiency caused by a new point mutation combined with a previously undetected gene deletion

Abstract

A 3-week-old Caucasian female presented with severe unprovoked parenchymal cerebral haemorrhage. Her plasma factor VII (FVII) activity was <0.01 units/ml. FVII activities for her mother and sister were 0.65 units/ml and 0.51 units/ml, respectively, while her father's level was normal. These results indicated that the mother was heterozygous for a non-functional F7 gene that had also been inherited by the proband's sister. The proband's severe FVII deficiency was caused by a new mutation in her paternal F7 gene coupled with the inheritance of the non-functional maternal F7 gene. DNA sequence analysis revealed that the proband had apparent homozygosity for a novel single point mutation (g.3907G > A) changing the codon for Glu29 to Lys (E29K); neither parent had the E29K mutation. Because of the unlikelihood that the proband was homozygous for two identical new point mutations, the DNA sequence abnormality was more likely to have arisen from a single mutated gene on one allele and a F7 gene deletion on the other allele. Real time polymerase chain reaction (PCR) analysis confirmed that the proband had inherited a gene deletion that was present in the aternal side of the family. Subsequent clotting assays and real time PCR vealed that the maternal deletion also included the closely linked F10 gene.