Which facial malformation is an example of multifactorial inheritance?

• A. Harelip
• B. Cleft lip
• C. Facial palsy
• D. Down syndrome

Answer: (B)

Cleft lip is an exemplary case of multifactorial inheritance due to the complex interplay of genetic and environmental factors that contribute to its development. Multifactorial traits are influenced by multiple genes, along with various environmental influences. In the case of cleft lip, genetic predisposition can be affected by factors such as maternal nutrition, teratogenic exposures during pregnancy, and other external conditions, leading to the malformation.

Unlike conditions that have a clear single-gene or chromosomal cause, like Down syndrome, or those that are primarily the result of other distinct genetic pathways, cleft lip showcases how genetics and environment can work together to influence physical development. This multifactorial basis is crucial in understanding the occurrence of the condition within families and populations.