Variability of expression of oral-facial-digital syndrome type I in 15 Saudi girls: Why is there a high rate of median cleft lip in the phenotype?

BACKGROUND: It is well known that the incidence of nonsyndromal cleft lip and palate varies greatly according to ancestry: 0.3 to 0.4 per 1000 live births in blacks, one in 1000 in Caucasians, and two in 1000 in Asians and individuals from the central province of Saudi Arabia. Median cleft lip is a variable feature in oral-facial-digital syndrome type I (OFD-I). OBJECTIVE: To test the hypothesis that genetic factors may determine the lip phenotype in OFD-I patients. METHODS: A study involving 15 Saudi girls (from the central province of Saudi Arabia) with OFD-I showed a high rate (93.3%) of median cleft lip and palate. This rate in OFD-I patients is known to range from 33% to 56% in Caucasians and also known to be very low in blacks. The authors compared the rate of median cleft lip with or without cleft palate in the Arabian series (93.3%) with the rate in Caucasians and blacks. RESULTS: The difference in median cleft lip with or without cleft palate among the three groups was significant. CONCLUSION: This supports the hypothesis that ancestral genetic factors may determine the lip phenotype in OFD-I patients.