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6-Pyruvoyl-Tetrahydropterin Synthase (PTPS) Deficiency
PTS gene
6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency is an autosomal recessive inborn error of tetrahydrobiopterin (BH4) synthesis that accounts for approximately 60% of all tetrahydrobiopterin deficiencies. BH4 is a cofactor essential for phenylalanine hydroxylase, and tryptophan and tyrosine hydroxylases; decreased activities of the latter enzymes is likely the cause of the neurologic symptoms associated with this disorder. Infants develop neurological symptoms even though blood phenylalanine levels are normal. Approximately 80% of patients with PTPS deficiency present with the severe “typical” form characterized by early onset of severe neurological symptoms including microcephaly, psychomotor retardation, tonal abnormalities, seizures, hypothermia and hyperthermia (without infections), swallowing difficulties and hypersalivation. Other features include mental retardation and microcephaly. The clinical course of severe PTPS deficiency may be similar to that in other inborn errors of BH4 metabolism namely dihydropteridine reductase deficiency and GTP cyclohydrolase I deficiency. Less severely affected patients are classified as having a mild/peripheral or “atypical” form of PTPS deficiency with symptoms ranging from transient hyperphenylalanemia to cases where a mild form progresses into a severe form. In a study of 25 Chinese patients with deficient PTPS enzyme activity, mutation analysis identified a sequence variant in 98% of alleles. In multiple smaller studies (studies including between 1-4 patients) of patients from varied ethnic backgrounds with deficient PTPS enzyme activity, mutations were found on 83-100% of alleles.
Using genomic DNA, bi-directional sequence of coding exons and corresponding intron/exon boundaries of the PTS gene (1-6) is analyzed. If sequencing identifies a mutation on only one allele of the PTS gene, and if clinically indicated, reflex deletion/duplication testing (ExonArrayDx) will be performed at no additional charge to evaluate for a deletion/duplication of one or more exons of this gene. Mutations found in the first person of a family to be tested are confirmed by repeat analysis using sequencing, restriction fragment analysis, or another appropriate method.
Information Sheet, including prices and CPT codes
Consent Document
Genetic Test Sample Submission Form (Test Requisition Form) including Payment Options
PTS DEFICIENCY, 6-@PYRUVOYL-TETRAHYDROPTERIN SYNTHASE DEFICIENCY, cerebrospinal, HPA, neurotransmitters, monoamine, L-dopa, carbidopa, 5-hydroxytryptophan, tetrahydopterin, biopterin
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