Pre-pregnancy genetic screening typically covers many hereditary diseases and hundreds of mutations. Two physician-scientists at Rambam Health Care Campus (Rambam) in Haifa, Israel, have discovered a new mutation linked to a specific type of autism that occurs most frequently in Ashkenazi Jews. Pre-natal testing for this gene has now been added to the national health basket.
Dr. Sharon Bratman-Morag, a genetic counselor at Rambam’s Genetics Institute, together with Dr. Karin Weiss, the institute’s director have been looking for genetic links to autism. Their research began six years ago when a brother and sister with developmental delays and movement disorders visited the hospital’s Genetic Institute. Initial scans found no known genetic condition. However, further analysis revealed a rare mutation in the tubulin folding cofactor B gene. Subsequent research between Rambam and the Technion-Israel Institute of Technology confirmed this mutation’s role in the condition of the twins.
The condition is an autosomal recessive genetic disorder, meaning that if both parents are carriers; their child has a 25% chance of developing this form of autism, intellectual disability, and a movement disorder that typically appears around age nine. Furthermore, the mutation appears more frequently in Ashkenazi Jews (1:80) as compared to the rest of the population (5:100,000).
Bratman-Morag explains that early diagnosis of autism is challenging because multiple genes are involved. Even with comprehensive pre-pregnancy genetic testing, the risk of autism remains.
Through the national health system and genetic institute laboratories, couples contemplating pregnancy — or those already pregnant — can undergo comprehensive genetic screening via a simple blood test. If the results confirm that both parents are carriers of the mutated gene, they are referred for counseling due to the high carrier frequency.
With this information, Bratman-Morag and her colleagues reviewed Israeli and international genetic databases and identified 10 children and young people with similar symptoms of autism and movement disorders. It was discovered that all of these patients were of Ashkenazi descent and shared the same rare mutation.
On average, each person carries mutations for about five hereditary diseases. However, if we have a normal copy of each gene, we remain healthy because. Common diseases included in genetic screening are Tay-Sachs (prevalent among Ashkenazi Jews), cystic fibrosis (common across all populations), and Propionic Acidemia (prevalent among those of Moroccan descent).
Technological advancements have expanded screening protocols to cover many more hereditary diseases. Gynecologists now routinely refer couples for genetic screening. Costs have decreased significantly, making it feasible to screen for hundreds of diseases simultaneously. Screening both partners for the most common genetic diseases is part of Israel’s new approach to identifying potential risks.
If discovered that the biological parents are carriers their child has a 25% chance of inheriting two defective genes and developing the disease. In such cases, the parents have two options enabling them to make informed decisions:
Natural Conception: Early in the pregnancy, an amniocentesis or placental tissue test can determine if the fetus has inherited two defective copies of the gene. Test results are available within eight weeks.
In Vitro Fertilization (IVF): Fertilized eggs are tested, and only healthy embryos with at least one normal copy of the gene are transferred to the uterus. The presence of one normal copy of the gene reduces the risk of developing this form of autism.
Recognizing the importance of the physicians’ research results, the Ministry of Health has added this test to the standard pre-pregnancy screening protocols and is now part of the national health basket.