Editor—Two mutations have been identified in recent years that predispose a heterozygous carrier to venous thrombosis. One is a mutation localised to the factor V gene, Arg 506 to Gln (factor V Leiden mutation, FVL), which has been shown to be the most common cause of familial thrombosis1 2 through resistance to activated protein C (APC), which is an inhibitor of activated factors V and VIII.3 The second is in the gene for the coagulation factor prothrombin (factor II), the G20210A mutation.4

There are two published estimates of prevalence of theFVL mutation in the Australian population, the first in a study of recurrent miscarriage,5 where 3.5% of the controls had FVL. The other is a recent study of blood donors where 3.6% were found to be heterozygous.6

Fewer studies have been done on the prothrombin (PT) mutation which is not as prevalent, thought to occur in approximately 2% of healthy, normal controls.1 4

Of particular relevance to this study are the findings of children with ischaemic strokes7-9 or thromboembolism,10 11 who have been reported as having a high prevalence of the FVL mutation. A more recent study12 suggests that neitherFVL nor PT is a risk factor for childhood stroke and that “a large prospective multicentre study is required” to investigate this further. There has also been a report of three babies with hemiplegic cerebral palsy (CP) who were heterozygous for the FVLmutation.13 In the three cases, there was a suggestion that placental infarction/thrombosis or neonatal stroke may have occurred and resulted in the hemiplegia. Other relevant studies have also been done, suggesting that placental infarction and late fetal loss14 15 may occur more frequently in women who are carriers of FVL.

Cerebral …