A mutant gene carried by 5 percent of Caucasus Jews – “Mountain Jews” or Juhuri, mostly from Azerbaijan and Dagestan – that can cause brain atrophy in children if both parents are carriers has been discovered by researchers at Hadassah University Medical Center in Jerusalem’s Ein Kerem.The identification of the mutation will make it possible for couples to be screened and prevent the birth of babies who would otherwise suffer from severe mental retardation.The findings, which will be published in the print edition of the American Journal of Human Genetics in November, were released on Thursday night by its online edition.The team of researchers included Dr. Avraham Shaag, Dr. Shamir Zenvirt and Prof.Orly Elpeleg from the hospital’s department of genetic and metabolic diseases and Prof. Ophry Pines of the department of microbiology and molecular genetics of the Hebrew University Medical Faculty.Eighty babies of Caucasus origin had been born recently in hospitals throughout Israel.Their anonymous blood samples were sent to Hadassah.At four to nine weeks of age, four of the infants suddenly began to suffer neurological symptoms – muscle tension, serious disquiet, convulsions and difficulty smiling and nursing. Those affected developed mental retardation, seizures, spasticity, epilepsy and brain and cerebellum atrophy.This ethnic group does not include the Georgian Jews of the Caucasus Mountains, but rather “Mountain Jews” and Tats who are believed to have inhabited Caucasia for a long time. Their distant forefathers once lived in southwest Persia, the southwestern part of present-day Iran.The predecessors of the “Mountain Jews” settled in Caucasian Albania in the fifth and sixth centuries CE. They were genetically isolated for around 2,500 years. After fleeing persecution in Persia, they moved north to mountain villages on both sides of the high peaks between the Black and Caspian Seas. Twenty years ago, with the fall of the Soviet Union, many of the Caucasian Jews immigrated to Israel, the US and Europe.The Hadassah researchers located an identical area on Chromosome #11 of all affected infants, of which one genetic mutation has been found to cause the tragic phenomenon.As 80 babies is a small sample, the frequency of the gene might change in a bigger sample, the researcher says.During the past three years the team of Hadassah researchers headed by Elpeleg has discovered 15 genes whose mutation can cause the birth of children with genetic diseases.