October 19, 2007
During the early 1900s, doctors believed cleft lip and cleft palate were developmentally related. But in the early 1940s, new evidence emerged that showed they were distinct developmental entities, resulting in today’s umbrella designation of cleft lip and/or palate. As some have noted, the “and/or” designation can lull scientists into a binary mindset that causes them to miss other related but subtle birth defects in children born with clefts. Identifying these complex phenotypes is particularly important as scientists discover more genes involved in clefting and need additional clues to figure out their functions. As reported in the October issue of the Journal of Dental Research, NIDCR grantees and colleagues examined a mixed group of people in Brazil to see if clefts and dental anomalies could be used in combination to define new subphenotypes of clefting. Among the 500 people in the study with clefts, the researchers found 23 had multiple dental anomalies. Of those, 20 people had tooth agenesis, most frequently involving the lateral incisor on the non-cleft side of the mouth. The researchers propose that the improper development of the lateral incisor may suggest incomplete forms of bilateral clefts of the lip.