PUBLIC RELEASE DATE:

9-May-2014

Contact: Nicole Giese Rura rura@wi.mit.edu 617-258-6851 Whitehead Institute for Biomedical Research

CAMBRIDGE, Mass. (May 9, 2014) 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.

HFM affects approximately one in 3,500 births. While some cases appear to run in families, no gene had been found to be causative. That is until Whitehead Fellow Yaniv Erlich and his lab set out to do just that. Their work is described in this week's issue of the journal PLOS ONE.

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.

Thought to be brought on by circulation difficulties during embryonic development, HFM is also thought to be sporadicmeaning that it occurs spontaneously rather than through inheritance. However, one family in northern Israel has more than its share of the anomaly.

To identify the origin of this family's disorder, 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.

"What's unique here is that this is the largest family with this disorder described in the literature," says Erlich. "Most of the time, you see one person affected, or perhaps two peoplea parent and a child. Such a large family increases the power of the genetic study and clearly signals that there is a genetic component to a disease."

To find the cause of this 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.

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Scientists find gene behind a highly prevalent facial anomaly

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