Cleft lip (CL) and palate (CP) occurs as part of many other mal-formation syndromes in a non-specific manner more frequently than would be expected. The aetiology of isolated clefts, without syndromic features or family history, however, is likely a result of genetic and environmental factors.
The population incidence is:
- 1 in 500 - 1 in 1000 for cleft lip (with or without cleft palate). It is unilateral in 80% of cases with the left side more commonly affected. Males are often more severe.
- 1 in 2500 for isolated cleft palate. The spectrum of abnormalities ranges from bifid uvula to submucous cleft to velopharyngeal insufficiency (regurgitation of milk in children to nasal speech in adults).
Recent case control studies have shown that periconceptual folate supplementation has a 47% risk reduction in CL/P in offspring of when compared to no maternal folate supplementation.
- A dose of 5mg/day is recommended for women with a previous occurrence and 400mcg/day where there is no prior history.