描述
Histidinemia (Histidine Ammonia-Lyase Deficiency; HAL Deficiency; Histidase Deficiency; HIS Deficiency) is an autosomal recessive disease caused by a mutation in the HAL gene which codes for hisitidine ammonia-lyase. A deficiency in this enzyme results in accumulation of L-histidine in serum, spinal fluid, and urine; histamine in plasma and urine; and imidazoleacetic acid, imidazolactic acid, and 1-methylhistamine in urine. Symptoms include organic acids in urine, mental retardation, and delayed speech development. Treatment includes a low-histamine diet.