title: The STR system in the human phenylalanine hydroxylase gene: true fragment length obtained with fluorescent labelled PCR primers.
abstract: We present a simple, fast, non-radioactive method for the analysis of the polymorphic short tandem repeat (STR) system in the human phenylalanine hydroxylase gene. Previously, sizing of the STR marker involved radiolabelling of PCR amplified fragments and resolution on denaturing polyacrylamide gels using M13 sequencing ladder as a standard. However, this method consistently gave sizes 2 bp longer than the known sequence. The fluorescent method presented here employs internal lane standards and enables accurate sizing of the fragments. To avoid confusion, we suggest that the true fragment lengths are used as reference values in the future. The analysis of STR alleles is valuable for population genetic studies and for targeted mutation screening in phenylketonuria (PKU). It can replace RFLP-based haplotype analysis for carrier detection, and we report its use for prenatal diagnosis in a Northern Irish family with PKU. The analysis of 250 Northern Irish chromosomes, including 128 PKU alleles, showed no significant difference between normal and PKU alleles, with fragment lengths of 238 and 242 bp most common in both groups.
authors.affiliation: Department of Medical Genetics, Belfast City Hospital, Northern Ireland.
authors.forename: J
authors.initials: J
authors.lastname: Zschocke
authors.forename: C A
authors.initials: CA
authors.lastname: Graham
authors.forename: J J
authors.initials: JJ
authors.lastname: McKnight
authors.forename: N C
authors.initials: NC
authors.lastname: Nevin
mesh_terms: D005820:Genetic Testing / Q000379:methods*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D009660:Northern Ireland / Q000453:epidemiology; D010651:Phenylalanine Hydroxylase / Q000235:genetics*; D010661:Phenylketonurias / Q000453:epidemiology / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D012680:Sensitivity and Specificity
chemical_list: D010651:Phenylalanine Hydroxylase