U.S. study finds increased prevalence of left-handedness in children with facial development disorder

WASHINGTON, March 2 (Xinhua) -- A new study by physician
researchers from Hasbro Children's Hospital in Rhode Island and Children's
Hospital Boston has identified an increased prevalence in left-handedness
in children with a congenital disorder known as hemifacial
microsomia (HFM).

The study was published in the March 2009 edition of
the Journal of Craniofacial Surgery.

Overall, ten percent of the population is
left-handed. A higher frequency has been associated with certain craniofacial
malformations such as cleft lip and other conditions.

Albert Oh, director of pediatric plastic and
craniofacial surgery at Hasbro Children's Hospital, along with researchers from
Children's Hospital Boston, developed this study to determine if the frequency
of left-handedness increased in patients with HFM.

HFM is the second most common birth defect after
clefts, 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.

A total of 86 patients who were diagnosed with HFM
were studied and compared to a control group using several factors. The study
group was 48 percent male, 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 percent male with a mean age of 10
years.

When compared to the control group, the study group
showed 26 percent were left-hand dominant for writing compared with only 11
percent in the control group. Also of note, 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.

Albert Oh, who is also a professor of surgery at the
Warren Alpert Medical School of Brown University, says: "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."

Oh and the authors also note that the study should
promote further discussion of the two major etiological theories of HFM:
vascular disruption and abnormal proliferation or migration of neural crest
cells (cells located in the neural plate in the embryo that migrate to their
final destinations during embryo development).

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.