In the 1930s, two families, the Jessops and the Barlows, settled the area around Hildale, Utah, along the border with Arizona, where they founded the FDLS — and began handing down to their descendants a recessive gene for a severe form of mental retardation called Fumarase Deficiency. The birth defect has become increasingly prevalent within the FLDS community since 1990 when it was first identified by Dr. Theodore Tarby, an Arizona pediatric neurologist, now retired but formerly with the Children's Rehabilitative Services in Phoenix. He saw his first case when an FLDS mother brought her severely retarded son to see him. Tarby asked the mother whether any of her other children had problems, and she mentioned a daughter with cerebral palsy — testing proved that she, too, had Fumarase Deficiency syndrome.
The birth defect — an enzyme deficiency — causes severe mental retardation, epilepsy and disfigurement of features. "The retardation is in the severe range — an IQ around 25," Dr. Tarby says. Afflicted children are missing portions of their brain, often cannot sit or stand, and suffer grand mal seizures and encephalitis. Language skills are nonexistent or minimal. "I remember one little girl has a fascination with coins and the only word she could say was 'money,'" the doctor said. Families whose children are affected often avail themselves of state-funded medical care, consistent with the FLDS philosophy of seeking government aid — despite their suspicion of government — which they call "bleeding the Beast."