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Li L, Yang H, Zhao J, Yang N, Gong L, Tang Y, Kong Y. Identification and molecular analysis of 11 cases of the PTS gene variants associated with tetrahydrobiopterin deficiency. Front Genet 2022; 13:919209. [PMID: 36212127 PMCID: PMC9536429 DOI: 10.3389/fgene.2022.919209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 07/07/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Tetrahydrobiopterin deficiency (BH4D) is a rare autosomal recessive amino acid metabolic disease that belongs to a kind of hyperphenylalaninemia (HPA), and 6-pyruvyltetrahydrotrexate synthase (PTPS) deficiency is the most common type of BH4D. This study investigates the clinical and genetic characteristics of 11 PTPS deficiency cases in the Beijing area, identifies the genetic pathogenic factors, and evaluates the value of high-throughput sequencing in the precise diagnosis of PTPS deficiency.Methods: The Beijing Neonatal Disease Screening Center diagnosed patients with HPA. The study used phenylalanine (Phe) in blood, the ratio of Phe to Thr, urotrexate spectrum analysis, erythrocyte dihydrotrexate reductase (DHPR) activity determination, and high-throughput sequencing as methods. Bioinformatics software analyzed the variants’ pathogenicity and used RT-PCR to identify deep intron variants’ pathogenicity.Result: Among 635 cases with HPA, 38 cases were diagnosed with BH4D, of which the incidence in HPA was 5.98%. Nine kinds of PTS gene variants were detected, including seven missense variants, one splicing variant, and one deletion variant. The splicing variant c.84–291A>G had three splicing results in vivo: normal length, 79bp pseudoexon insertion, and exon 3 skipping. Bioinformatics and Sanger sequencing were performed to verify the identified variants.Conclusion: High-throughput sequencing is a helpful tool for clinical diagnosis and differential diagnosis of BH4D. This study confirms that c.84–291A>G is the hot spot variant of PTPS deficiency, and it is the first reported variant with a new splicing pattern in vivo. A novel deletion variant c.84_163del (p.Lys29Cysfs∗9) was found to enrich the genetic variant spectrum of the disease.
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Manti F, Nardecchia F, Banderali G, Burlina A, Carducci C, Carducci C, Donati MA, Gueraldi D, Paci S, Pochiero F, Porta F, Ortolano R, Rovelli V, Schiaffino MC, Spada M, Blau N, Leuzzi V. Long-term clinical outcome of 6-pyruvoyl-tetrahydropterin synthase-deficient patients. Mol Genet Metab 2020; 131:155-162. [PMID: 32651154 DOI: 10.1016/j.ymgme.2020.06.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/17/2020] [Accepted: 06/18/2020] [Indexed: 12/14/2022]
Abstract
INTRODUCTION 6-Pyruvoyl-tetrahydropterin synthase deficiency (PTPSd) is a rare autosomal recessive disorder of synthesis of biogenic amines, which is characterized by variable neurological impairment and hyperphenylalaninemia. We aimed to assess the long-term clinical outcome of this disorder and the factors affecting it. METHODS At total of 28 PTPSd patients (aged 19.9 ± 10.9 years) underwent clinical (neurological and psychiatric) and neuropsychological assessment (BRIEF, VABS-II, and IQ). Based on CSF homovanillic (HVA) and 5-hydroxyindolacetic acid (5-HIAA) and pterin concentrations at diagnosis, patients were classified as having either a severe [SF; low level of CSF, HVA, and 5-HIAA with altered neopterin/biopterin (Neo/Bio)] or mild form (MF; normal HVA and 5-HIAA with altered Neo/Bio) of PTPSd. RESULTS Approximately 36% of patients had MF PTPSd. At the last examination, 43% of patients had movement disorders (2 MF, 10 SF), 43% of patients had variable degrees of intellectual disability (SF only), 39% met the criteria for a psychiatric disorder (3 MF, 9 SF). Applying a linear regression model, we found that HVA and phenylalanine levels at birth had a significant influence on IQ, BRIEF, and VABS-II variability. Lastly, 5-HIAA further contributed to VABS-II variability. The disease showed a self-limiting clinical course and its treatment, although delayed, is effective in improving the neurological status. CONCLUSIONS Neurodevelopmental impairment due to PTPSd shows a self-limiting course. A continuous improvement in the neurological condition has been observed in patients receiving treatment, even when delayed. The severity of brain biogenic amine depletion at diagnosis predicts neurological and psychiatric outcomes.
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Affiliation(s)
- Filippo Manti
- Department of Human Neuroscience, Unit of Child Neurology and Psychiatry, Sapienza University, Rome, Italy
| | - Francesca Nardecchia
- Department of Human Neuroscience, Unit of Child Neurology and Psychiatry, Sapienza University, Rome, Italy
| | - Giuseppe Banderali
- Department of Pediatrics, University of Milan, San Paolo Hospital, Santi Paolo e Carlo ASST, Milan, Italy
| | - Alberto Burlina
- Division of Inherited Metabolic Diseases, Department of Paediatrics, University Hospital of Padova, Padova, Italy
| | - Carla Carducci
- Department of Experimental Medicine, Sapienza University of Rome, Italy
| | - Claudia Carducci
- Department of Experimental Medicine, Sapienza University of Rome, Italy
| | | | - Daniela Gueraldi
- Division of Inherited Metabolic Diseases, Department of Paediatrics, University Hospital of Padova, Padova, Italy
| | - Sabrina Paci
- Department of Pediatrics, University of Milan, San Paolo Hospital, Santi Paolo e Carlo ASST, Milan, Italy
| | | | - Francesco Porta
- Department of Pediatrics, AOU Città della Salute e della Scienza di Torino, University of Torino, Italy
| | - Rita Ortolano
- Department of Medical and Surgical Sciences, Pediatric Unit, Regional Centre for Expanded Newborn Screening, S. Orsola-Malpighi University Hospital, Bologna, Italy
| | - Valentina Rovelli
- Department of Pediatrics, University of Milan, San Paolo Hospital, Santi Paolo e Carlo ASST, Milan, Italy
| | | | - Marco Spada
- Department of Pediatrics, AOU Città della Salute e della Scienza di Torino, University of Torino, Italy
| | - Nenad Blau
- Division of Metabolism, University Children's Hospital Zürich, Switzerland
| | - Vincenzo Leuzzi
- Department of Human Neuroscience, Unit of Child Neurology and Psychiatry, Sapienza University, Rome, Italy.
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