WASHINGTON -- Scientists are hopeful that the discovery of a fatal gene mutation, now found only in Amish newborns, could be a major step toward preventing brain defects in babies worldwide.

The genetic disorder, known as Amish microcephaly, is specific to the Old Order Amish community in Lancaster County, Pa. It amounts to a breakdown in DNA creation that causes abnormally small heads and brains in fetuses and, eventually, death.

The 2 1/2-year study by the National Genome Research Institute in Bethesda, Md., is the first of its kind to link problems with DNA production to fetal brain development, said Dr. Leslie Biesecker, the report's lead author.

In Lancaster County -- where about 20,000 Amish people descend from only a few dozen who settled there in the 1700s from Germany -- 61 babies from 23 families have had the disorder.