Craniosynostosis in Western Australia, 1980-1994: a population-based study.

A craniomaxillofacial unit was established recently in Western Australia, and a study was carried out to provide some baseline characteristics of primary craniosynostosis in Western Australia and to investigate whether there has been any significant temporal change in birth prevalence. A case control study was conducted, using cases identified from a population-based register of birth defects, and a random sample of all births without a birth defect formed the control group. All subjects were born in Western Australia over the period 1980-1994 inclusive. The prevalence of craniosynostosis over the period 1980-1994 in Western Australia was 5.06 per 10,000 births. There was a significant linear increase in lambdoid synostosis over this period of 15.7% per year. Craniosynostosis was significantly more common among male infants, infants born preterm (<37 weeks gestation), breech presentation or presentations other than vertex, and infants born to fathers 40 years of age or older, even after accounting for known autosomal dominant syndromes. Other major birth defects were found in 11.2% of children with nonsyndromic craniosynostosis. Only 43 children (25.3%) with craniosynostosis were reported to have been seen by a geneticist. Thus, the prevalence of craniosynostosis in Western Australia is among the lowest reported. There is no current explanation for the increase in lambdoid synostosis. The increased risk of so-called nonsyndromic craniosynostosis with paternal age raises the possibility of undiagnosed new dominant mutations. This, along with the excess of other birth defects in children with craniosynostosis emphasises the need to ensure that these families are offered genetic counseling.