May 08, 2017
Phenylketonuria (PKU) is a metabolic disease of the new born in which there is decreased metabolism of the amino acid phenylalanine. If PKU is not treated, it may lead to seizures, intellectual disability, mental disorders, and behavioral problems. It may also cause light colored skin (hypopigmentation) and a musty smell from body. If mothers are not properly treated against PKU, their babies may have cardiac disorders, small head (microcephaly) and low birth weight. The disease cannot be detected by physical examination of the baby after birth. The disease is genetic and in inherited from parents. The disease is caused due to mutations in the PAH gene which leads to low levels of the enzyme phenylalanine hydroxylase. As a result, there is built up of dietary phenylalanine in the body to highly toxic levels. The disease is autosomal recessive, which means that there must be mutation of both the copies of the gene, for the disease to occur. Those who have one of the gene pair mutated, does not have the disease. 2 types of Phenylketonuria PKU are identified- classic PKU and variant PKU, depending on the enzyme function. Many countries conduct newborn screening programs for PKU.
The disease was first discovered by Ivar Asbjørn Følling in 1934 and affects about 1 in 10,000 to 25,000 babies. Males and females are equally affected by the disease.
The role of diet in the disease was discovered in 1953. Treatment of the disease is done with giving diet low in phenylalanine and special supplements/formula. The diet should be maintained lifelong and patients can lead almost a normal diet. Periodic monitoring is done with blood tests. The medicine sapropterin dihydrochloride is useful in some cases. Gene therapy holds promise in the treatment of the disease and currently research is on in this aspect.
Disclaimer: The information given in this write-up is purely for educating the reader. It is not meant to be a substitute for any advice from a medical expert.