Children seem normal for one year and then deteriorate, dying by age 10.
By JUDY SIEGEL-ITZKOVICHbeduin child 88 ap(photo credit: AP)
The genetic defect responsible for a severe neurodegenerative disease that is very common in a Beduin tribe in the Negev has been discovered by researchers at Ben-Gurion University of the Negev and Soroka University Medical Center in Beersheba. Stricken children seem completely normal until their first birthday, after which their neurological function declines steadily until they reach a fully vegetative state a year later and die between the ages of seven and 10.
Brain imaging of affected individuals demonstrated diffuse cerebellar atrophy and abnormal iron deposition in discrete parts of the brain. The disease, called infantile neuroaxonal dystrophy (NAD), is found in various populations around the world, especially in children resulting from consanguinious marriages (of first cousins and other close relatives). Until now, the molecular basis of the disease was unknown, and thus pre-natal diagnosis was not possible.
A research group headed by Dr. Ohad Birk of the human genetics lab at the National Institute for Biotechnology in the Negev and director of Soroka's genetics institute recently identified the specific gene mutated in this disease. The gene encodes a phospholipase - an enzyme which normally breaks down phospholipids, causing defective degradation of specific phospholipids in the brain of these patients.
The research was recently published in the American Journal of Human Genetics in parallel and independent of a similar study done by a research group in the US. studying the same disease in another population cohort. The research was done by doctorate student Shareef Khateeb together with Dr. Hagit Flusser, Dr. Rivka Ofir and other members of the team headed by Birk.
"The findings now enable carrier detection and prenatal diagnosis for this severe disease both in Israeli families, as well as in many families worldwide," said Birk. "In the longer run, molecular understanding of the disease mechanism might also enable novel treatment modalities. However, the findings have implications far beyond this disease. Iron deposition in the brain is found in ageing, as well as in severe neurodegenerative diseases in adults, such as Alzheimer's and Parkinson's disease. The involvement of a defect in a phospholipase enzyme in a neurodegenerative disease accompanied by iron deposition opens a new field of research in these common neurodegenerative diseases."
The BGU lab focuses on unraveling the molecular basis of hereditary human diseases, based on studies of unique inbred communities in southern Israel. The research results are immediately implemented as genetic tests available to the community, promoting community welfare. Over the past two years, the research team have discovered the links between eight genes and human diseases and has introduced more than two dozens novel genetic tests.