Effect of Experimental Phenylketonuria on the Bone of Pregnant Mothers and their young during Perinatal Life and after Delivered Newborn of Albino Rats

Phenylketonuria (PKU) is a genetic disorder that is characterized by an inability of the body to utilize the essential amino acid, phenylalanine. The disease results from a deficiency in phenylalanine hydroxylase, the enzyme catalyzing the conversion of phenylalanine to tyrosine. Although, this inborn error of metabolism was among the first in humans to be understood biochemically and genetically, little is known about the mechanisms involved in the pathology of PKU during neonatal development. Elevated concentrations of plasma phenylalanine were induced in pregnant rats by oral administration of 50mg/100g body weight alpha-methylphenylalanine plus phenylalanine supplementation at a dosage of 60mg/100g body weight two times daily after the 6th day of onset of gestation till 14 & 16 days of gestation as well as at parturition. Treatment with alpha-methylphenylalanine/ phenylalanine resulted in a significant decrease of accumulated body weight gain during pregnancy as well as exhibited marked growth retardation of prenatal fetuses and delivered newborn. The growth retarded fetuses was manifested by decreased body weight, malformed both fore- & hindlimb, oedematous skin & superficial hematomas widely spread in different parts of the body. Ossification of bones was greatly altered. Skeletal abnormalities restricted mainly in skull, sternebrae, lumbar, caudal vertebrae and distal phalanx of both fore- & hindlimb. Histological examination of femoral bone revealed varieties of histopathological abnormalities which illustrated and discussed. These results suggested that exposure of the fetus to high plasma concentrations of phenylalanine cause deformities of bone.