Identification of the Most Common Mutations in the Phenylalanine Hydroxylase (PAH) Gene & Quinoid Dihydropteridine Reductase (QDPR) Gene in Jordanian Patients.
Phenylketonuria (PKU) is an autosomal recessive metabolic disorder in which the body is unable to process an essential amino acid, Phenylalanine (Phe). Accumulation of Phe to harmful levels in the body causes intellectual disability, irreversible brain damage and other serious health problems. The most severe form of this disorder is known as classic PKU and it results from PAH gene mutations whereas less severe form of this condition is sometimes referred to as variant PKU and non-PKU hyperphenylalaninemia and is caused by mutations in QDPR and other genes).
The PKU project was initiated in collaboration with Ministry of Health in 2007. In 2008 the National Jordanian Screening Program (NJSP) was established and according to this program the incidence of PKU in the Jordanian population is 1/4000 while the average incidence in Caucasian population of 1/10000.
Currently there are more than 116 families registered on the Jordanian Charity Association for Phenylketonuria (JCA PKU). In 2009 PKU project was started at the NCDEG, aiming for identification of the most common mutations in the PAH & QDPR genes in order to introduce the diagnosis, carrier, prenatal and neonatal testing and genetic counseling to the affected families.
Our sample pool consisted of 49 unrelated families, with more than 69 affected individuals. Up to now 35 families have been genetically diagnosed. 33 families were diagnosed with classical PKU (PKU I), having mutations within the PAH gene and two families were diagnosed with DHPR deficiency, having 2 different mutations within the QDPR gene.
The results obtained so far provide an experimental framework to define the most common mutations within the Jordanian population. Our future direction is to establish a national scale statistical database, performing full PAH and QDPR gene sequencing, hoping to understand the genotype-phenotype correlation within our population and provide dietary management for the PKU patients.