BGU re­searchers iden­tify mu­ta­tion caus­ing ge­netic dis­ease com­mon in Moroc­can Jews

The Jerusalem Post - - NEWS - • By JUDY SIEGEL

The gene mu­ta­tion re­spon­si­ble for a dis­ease that causes epilepsy and se­vere men­tal re­tar­da­tion has been dis­cov­ered by re­searchers at Ben-Gu­rion Univer­sity of the Negev, mak­ing early de­tec­tion pos­si­ble. The dis­cov­ery makes it pos­si­ble for po­ten­tial car­ri­ers of the mu­ta­tion to be tested, and in cases of in-vitro fer­til­iza­tion, em­bryos can be tested as well. Those af­fected by the dis­ease would not be im­planted in the womb and this would bring about the erad­i­ca­tion of the dis­ease. Prof. Ohad Birk, head of the ge­net­ics in­sti­tute at Soroka Univer­sity Med­i­cal Cen­ter and the af­fil­i­ated Mor­ris Kahn Lab at BGU’s na­tional in­sti­tute for biotech­nol­ogy, dis­cov­ered the mu­ta­tion for the dis­ease, which the re­searchers have called PCCA2 (Pro­gres­sive cere­bello cere­bral at­ro­phy type 2). The dis­ease was shown to be caused by two mu­ta­tions in the VPS53 gene – both of them com­mon in Jews of Moroc­can an­ces­try, with one of ev­ery 37 Moroc­can Jews car­ry­ing one of the two mu­ta­tions. The Birk team showed that the mu­ta­tions cause de­fec­tive circulation within pa­tients’ cells, leading to detri­men­tal ex­ces­sive stor­age of “junk” in the cells. They re­cently pub­lished their study on­line in the Jour­nal of Med­i­cal Ge­net­ics. The re­search was fi­nanced by the Is­rael Sci­ence Foun­da­tion and the Legacy Her­itage fund. Ba­bies who are af­fected by the mu­ta­tion seem to be per­fectly nor­mal when they are born and de­velop well un­til about six month, at which point brain at­ro­phy pre­sents it­self and the in­fants be­gin to de­te­ri­o­rate – reach­ing se­vere re­tar­da­tion by age one. PCCA2 is a re­ces­sive dis­ease, this means that if both par­ents are car­ri­ers of a VPS53 mu­ta­tion there is a 25 per­cent risk of the dis­ease man­i­fest­ing in each preg­nancy. Based on the high car­rier rate, PCCA2 is the most com­mon se­vere ge­netic dis­ease in Moroc­can Jews dis­cov­ered so far, and rou­tine car­rier test­ing for this dis­ease in Moroc­can Jews will likely be avail­able within months. Four years ago, Birk’s group dis­cov­ered an­other gene for a sim­i­lar dis­ease – PCCA – which is com­mon in Jews of Moroc­can and Iraqi an­ces­try (1:40 car­rier rate in both co­horts). Un­like PCCA2, the mu­ta­tions in PCCA are in a gene called SESPSECS that can­cels the body’s abil­ity to uti­lize the es­sen­tial mi­cronu­tri­ent, se­le­nium. Thanks to this re­search, rou­tine, govern­ment-funded car­rier test­ing for SESPSECS mu­ta­tions was in­tro­duced in 2011 for all Jews of Moroc­can or Iraqi an­ces­try. PCCA and PCCA2 are the two most com­mon ge­netic dis­eases in Jews of Moroc­can her­itage, and have never been de­scribed be­fore world­wide. The re­search into PCCA2 was done as part of the doc­toral the­sis of Miora Fe­in­stein in Birk’s lab. Dr. Hagit Flusser, Prof. Bruria Ben-Zeev, Prof. Tally Ler­man-Sagie and Dr. Dorit Lev con­trib­uted to the clin­i­cal as­pects and Dr. Orly Agamy and oth­ers of the Birk lab took part in the molec­u­lar stud­ies. Birk’s re­search led to the dis­cov­ery of more than 20 ge­netic dis­eases com­mon in Arabs and Sephardi Jews, pro­vid­ing in­sights into the na­ture of ill­ness and un­rav­el­ing molec­u­lar path­ways of nor­mal hu­man de­vel­op­ment.

(BGU)

OHAD BIRK

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