BACKGROUND AND OBJECTIVE: X-linked dystonia parkinsonism (XDP, DYT3, MIM #314250) is a neurodegenerative movement disorder found endemically in the Philippines. An SVA retrotransposon insertion mutation has been described in patients with XDP, which requires Southern analysis for detection. However, this method is costly and time-consuming. Hence we developed a PCR-based method and validated it among our local population.

METHODS AND RESULTS: A total of 58 samples from 58 patients with a clinical diagnosis of XDP were collected. Other samples were from an obligate female carrier, two unaffected male relatives, and two patients with typical Parkinson’s disease. Primers designed to amplify the SVA retrotransposon found in the DYT3-TAF1 gene (NCBI Accession Number AB191243) were used. All patients were positive for the expected 3229-bp product after PCR amplification. The normal control showed a 599-bp product, while the female carrier showed both the 3229 and 599-bp product. Subsequent RFLP analysis using BamHI verified the presence of the SVA retrotransposon insertion mutation. CONCLUSION: Our results show that large-scale PCR-based testing to screen for genetic diseases with a relatively high prevalence such as XDP is possible in our setting. When followed by RFLP analysis, this can provide genetic confirmation of the diagnosis of XDP and facilitate proper genetic counselling and therapy.
Dystonia 3, Torsion, X-Linked

INTRODUCTION: Phenylketonuria (PKU), an autosomal recessive metabolic disorder caused by phenylalanine hydroxylase (PAH) deficiency, leads to hyperphenylalaninemia and neurological damage if untreated. This is the first study in the Philippines to identify the disease-causing mutations in the PAH gene of clinically diagnosed Filipino PKU patients.

METHODS: The study included four unrelated PKU patients detected by the Philippine Newborn Screening Program from 1996 to 2008. Plasma amino acid analyses for all patients showed increased phenylalanine and low to normal tyrosine levels consistent with the diagnosis of PKU. Mutations in the PAH gene were identified by genomic DNA extraction from dried blood spots of the patients, PAH exon amplification by polymerase chain reaction and subsequent bi-directional DNA sequence analysis.

RESULTS: All patients presented with significantly elevated phenylalanine levels on bacterial inhibition assay and thin layer chromatography. Urinary pterins confirmed the diagnosis of Tetrahydrobiopterin deficiency in two patients while the other 2 patients had the Classical PKU phenotype. Four previously identified mutations in the PAH gene (p.I65T, p.R413P, p.EX6-96A>G, p.R243Q) were identified in those with Classical PKU.

CONCLUSION: The present results confirm the heterogeneity of mutations at the PAH locus in Filipinos. Neonatal screening and the use of molecular diagnosis significantly aid in the medical management and genetic counseling of patients and their families.

Phenylalanine Hydroxylase ; Phenylalanine ; Neonatal Screening ; Genetic Counseling ; Tyrosine ; Pterins ; Chromatography, Thin Layer ; Philippines ; Phenylketonurias ; Exons ; Sequence Analysis, Dna ; Phenotype ; Dna

Objective: The observed irregularities in the biochemical profile and the limited information on long-term outcomes among patients with Duarte variant (D/G) galactosemia have led to patient management variability. This study examined the molecular characteristics of Filipino patients with presumed variant galactosemia for confirmation of diagnosis. It also aimed to describe the corresponding biochemical, clinical and neurodevelopmental profiles in order to gain a better understanding of the patients with normal galactose metabolites in spite of low to absent GALT activity detected by the local newborn screening program. Methods: Thirteen (13) patients who were presumed to have a variant form of galactosemia by national newborn screening between 2002 and 2010, and who previously underwent physical and neurodevelopmental assessment were included in the study. Repeat clinical, ophthalmologic and neurodevelopmental evaluations were done upon recruitment of participants. Direct sequence analysis of the coding region of the GALT gene was conducted to determine the patients’ genotypes. Results: None of the patients’ genotypes were consistent with Duarte variant (D/G) galactosemia. Their genotypes reflect the normal total blood galactose levels in patients, but were inconsistent with the absent or trace GALT activity. Conclusion Molecular testing for the entire cohort of presumed “variant” galactosemia Filipino patients will provide better profiling of this condition. Re-evaluation and assessment of the current guidelines used by national newborn screening in classifying variant galactosemia are recommended.
Galactosemias ; Neonatal Screening