According to a new study, kids with a congenital disorder, known as hemifacial microsomia (HFM), are more likely to develop left-handedness.
HFM is the second most common birth defect after cleft lips, and is a condition that affects the development of the lower half of the face. It most commonly affects the ears, mouth or jaw, and can occur on either side of the face or both.
Conducted by physician researchers from Hasbro Children's Hospital and Children's Hospital Boston, the new study was aimed at finding out whether the frequency of left-handedness increases in patients with HFM.
In the study, Albert Oh, MD, director of pediatric plastic and craniofacial surgery at Hasbro Children's Hospital, along with researchers from Children's Hospital Boston, analyzed 86 patients who were diagnosed with HFM and compared them to a control group using several factors. The study group comprised 48 percent male patients, with an average age of 13.5 years. Of those patients, 49 percent had predominant right side involvement of HFM, while 38 percent had left side involvement and 13 percent had almost equal involvement on both sides.
The control group included 96 children-44 per cent male with a mean age of 10 years.
After comparing to the control group, researchers found that the study group showed 26 percent were left-hand dominant for writing compared with only 11 percent in the control group.
They pointed out that for the patients who had bilateral involvement of their HFM, the side most affected was uniformly predictive of hand preference.
The patients with left-predominant involvement of HFM were left-handed, and the patients with right-predominant involvement were right-handed.
Oh said: "This study is significant in that it revealed a significant shift to left-hand preference in patients with HFM. This finding further emphasizes that the developmental abnormality that causes HFM is not isolated to the face."
The study, while limited in size, found no correlations between the side of facial involvement and hand preference that would support the theory of vascular disruption.
The study has been published in the Journal of Craniofacial Surgery.