Gene behind highly prevalent facial anomaly found

Whitehead Institute scientists have identified a genetic cause of a facial disorder known as hemifacial microsomia (HFM). The researchers find that duplication of the gene OTX2 induces HFM, the second-most common facial anomaly after cleft lip and palate. The researchers find that duplication of the gene OTX2 induces HFM, the second-most common facial anomaly after cleft lip and palate.

HFM affects approximately one in 3,500 births. While some cases appear to run in families, no gene had been found to be causative. Patients with HFM tend to have asymmetrical faces, --typically with one side of the upper and lower jaws smaller than the opposite side--a smaller or malformed ear on the affected side, and, in some cases, neurological or developmental abnormalities.

 

The genetic cause of this girl's hemifacial microsomia (HFM) was the focus of research conducted by Whitehead Institute Fellow Yaniv Erlich and his lab..

Erlich and lab technician Dina Zielinski began studying the genomes of a five-year-old female member of the family, along with those of her mother, grandmother, and male cousin, who all exhibited traits of HFM. Later, the genetic information from the grandmother's Russian cousin, who resides in the Philadelphia area, was recruited to the study.To find the cause of a family's HFM, Zielinski began by searching for a point mutation, but the five of the study participants held no such mutation in common. Next she looked for sections of the genome that are duplicated. All had an extra copy of one 1.3 megabase pair section of chromosome 14. Duplications this large are frequently detrimental. Within this large piece of DNA, he identified eight candidate genes that could cause the type of HFM running in this family. She then used two algorithms to compare the molecular signatures of these eight genes to other genes known to be responsible for various facial malformations with features similar to HFM. After this analysis, the gene OTX2 that codes for a transcription factor rose above the seven other candidates.

Intriguingly, another, darker role of OTX2 was highlighted during the course of the study. The little girl who was this research's main focus was diagnosed with medulloblastoma, a highly malignant tumor originating at the base of the brain in or near the cerebellum. OTX2 is a known oncogene for her subclass of medulloblastoma, confirming that her OTX2 expression is out of line.

Posted by

Keerti Mishra