Novel lip pit phenotypes and mutations of IRF6 in Van der Woude syndrome patients from Pakistan.

The role of interferon regulatory factor 6 (IRF6) gene mutations in causing Van der Woude syndrome (VWS) and poplyteal pterygium syndrome has been described in different populations worldwide. The former is one of the major syndromes of cleft lip and/or cleft palate (CL/P) with the distinct phenotype of presence of pits with or without sinuses on the lower lip. We identified seven probands with VWS from Punjab province of Pakistan and recognized two previously unreported lip pit phenotypes. The mutational analysis of IRF6 in this cohort revealed four novel and two previously reported mutations. The newly identified mutations include three frameshifts (c.635delG; c.21_33del13; c.627delC) and one transition mutation (c.2T>C) affecting the first codon of IRF6. Together with a past epidemiological study on VWS in Pakistan, the frequency of this syndrome among CL/P individuals from Punjab was calculated to be 1.17%.