- 1 in 3,000 births.
- Two or more digits (bone or soft tissue) are fused together.
- Chromosomal abnormalities: common finding in triploidy.
- In most cases it is an isolated finding, but there is a common association with genetic syndromes:
- Apert syndrome: autosomal dominant; brachysyndactyly of hands and feet, craniosynostosis, hypertelorism, heart defects.
- Carpenter syndrome: autosomal recessive; polysyndactyly, craniosynostosis.
- Fraser syndrome: autosomal recessive; microphthalmia, facial cleft, tracheal atresia, bilateral renal agenesis, heart defects, syndactyly or polydactyly.
- Detailed ultrasound examination.
- Follow-up should be standard.
- Standard obstetric care and delivery.
- Isolated cases: good prognosis.
- Isolated familial polysyndactyly: 50%.
- Part of Apert syndrome: 50%.
- Part of Carpenter and Fraser syndrome: 25%.
- Part of triploidy: no increased risk.