one-year-old tot will not survive long enough to even go to school.Little Rowan has a rare condition called Tay-Sachs Disease, a genetic condition which causes progressive damage to the nervous system.It affects just one in 320,000 babies – although it is more common within the Ashkenazi Jewish population of Eastern Europe where one in 3500 babies are born with it.The family do not think there are Ashkenazi antecedents on either side and Rowan’s brother and sister Aaron, seven, and Gracie, five, do not have the condition.Mum Deborah McDonald, 26, and delivery driver dad Aaron Packer, 25, had never even heard of the condition before Rowan was diagnosed.Deborah, who trained as a nurse for a time, said: “I’d heard about other genetic.