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Bisello G, Franchini R, Carmona CAC, Bertoldi M. Mild/moderate phenotypes in AADC deficiency: Focus on the aromatic amino acid decarboxylase protein. J Inherit Metab Dis 2024. [PMID: 39166734 DOI: 10.1002/jimd.12791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Revised: 08/06/2024] [Accepted: 08/07/2024] [Indexed: 08/23/2024]
Abstract
AADC deficiency is a severe neurometabolic inherited rare disorder due to the absence or decrease of dopamine and serotonin levels, causing deep motor and neurodevelopmental impairments. The disease is often fatal in the first decade of life, and pharmacological treatments (dopamine agonists, pyridoxine, and monoamine oxidase inhibitors as the first-line choices) can only alleviate the symptoms. Gene therapy surgery is now available for severe patients in the European Union and the United Kingdom, and follow-up data witness encouraging improvements. In the past few years, mostly due to the increased awareness and knowledge of AADC deficiency, together with newborn screening programs and advancements in methods for genetic diagnosis, the number of mild/moderate phenotypes of AADC deficiency patients has increased to 12% of the total. A review of the genotypes (homozygous/compound heterozygous) of AADC deficiency mild/moderate patients is presented here. The pathogenicity classification of each genetic variant is discussed. Then, we focused on the type of AADC protein possessed by patients and on the predictable structural score of the homodimeric/heterodimeric species of each protein variant. Since the terminology used for genetic and protein variants is the same, we highlighted how it could be misleading. We analyzed the loss-of-function as a fold-change decrease of activity of the recombinant purified AADC enzyme(s) theoretically synthesized by mild/moderate patients. A minimal residual kcat of 8% and/or kcat/Km of 1% seems necessary to avoid a severe disease manifestation. Overall, this cluster of mild/moderate patients needs consideration for a more appropriate and aimed therapeutic approach.
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Affiliation(s)
- Giovanni Bisello
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Rossella Franchini
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | | | - Mariarita Bertoldi
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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Bisello G, Saris CG, Franchini R, Verbeek MM, Willemsen MA, Perduca M, Bertoldi M. An attenuated, adult case of AADC deficiency demonstrated by protein characterization. Mol Genet Metab Rep 2024; 39:101071. [PMID: 38524666 PMCID: PMC10958467 DOI: 10.1016/j.ymgmr.2024.101071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 03/10/2024] [Accepted: 03/10/2024] [Indexed: 03/26/2024] Open
Abstract
A case of an adult with borderline AADC deficiency symptoms is presented here. Genetic analysis revealed that the patient carries two AADC variants (NM_000790.3: c.1040G > A and c.679G > C) in compound heterozygosis, resulting in p.Arg347Gln and p.Glu227Gln amino acid alterations. While p.Arg347Gln is a known pathogenic variant, p.Glu227Gln is unknown. Combining clinical features to bioinformatic and molecular characterization of the AADC protein population of the patient (p.Arg347Gln/p.Arg347Gln homodimer, p.Glu227Gln/p.Glu227Gln homodimer, and p.Glu227Gln/p.Arg347Gln heterodimer), we determined that: i) the p.Arg347Gln/p.Arg347Gln homodimer is inactive since the alteration affects a catalytically essential structural element at the active site, ii) the p.Glu227Gln/p.Glu227Gln homodimer is as active as the wild-type AADC since the alteration occurs at the surface and does not change the chemical nature of the amino acid, and iii) the p.Glu227Gln/p.Arg347Gln heterodimer has a catalytic efficiency 75% that of the wild-type since only one of the two active sites is compromised, thus demonstrating a positive complementation. By this approach, the molecular basis for the mild presentation of the disease is provided, and the experience made can also be useful for personalized therapeutic decisions in other mild AADC deficiency patients. Interestingly, in the last few years, many previously undiagnosed or misdiagnosed patients have been identified as mild cases of AADC deficiency, expanding the phenotype of this neurotransmitter disease.
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Affiliation(s)
- Giovanni Bisello
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biochemistry, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Christiaan G.J. Saris
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Geert Grooteplein 10, 6525 GA Nijmegen, the Netherlands
| | - Rossella Franchini
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biochemistry, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Marcel M. Verbeek
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Geert Grooteplein 10, 6525 GA Nijmegen, the Netherlands
- Translational Metabolic Laboratory, Department of Human Gentics, Radboud University Medical Centre, Geert Grooteplein 10, 6525 GA Nijmegen, the Netherlands
| | - Michel A.A.P. Willemsen
- Department of Pediatric Neurology, Radboud University Medical Centre, Geert Grooteplein 10, 6525 GA Nijmegen, the Netherlands
| | - Massimiliano Perduca
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Mariarita Bertoldi
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biochemistry, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
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Cursio I, Siliquini S, Carducci C, Bisello G, Mastrangelo M, Leuzzi V, Bertoldi M, Marini C. Case report: Childhood epilepsy and borderline intellectual functioning hiding an AADC deficiency disorder associated with compound heterozygous DDC gene pathogenic variants. Front Neurol 2023; 14:1284339. [PMID: 38116105 PMCID: PMC10729769 DOI: 10.3389/fneur.2023.1284339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 10/31/2023] [Indexed: 12/21/2023] Open
Abstract
Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare autosomal recessive neurometabolic disorder leading to severe combined serotonin, dopamine, norepinephrine, and epinephrine deficiency. We report on a female patient with borderline functioning and sporadic clear-cut focal to bilateral seizures from age 10 years. A neuropsychological assessment highlighted a mild impairment in executive functions, affecting attention span and visual-spatial abilities. Following the diagnosis of epilepsy with a presumed genetic etiology, we applied a diagnostic approach inclusive of a next-generation sequencing (NGS) gene panel, which uncovered two variants in trans in the DOPA decarboxylase (DDC) gene underlying an AADC deficiency. This compound heterozygous genotype was associated with a mild reduction of homovanillic acid, a low level of the norepinephrine catabolite, and a significant reduction of 5-hydroxyindoleacetic acid in cerebrospinal fluid. Remarkably, 3-O-methyldopa (3-OMD) and 5-hydroxytryptophan were instead increased. During the genetically guided re-evaluation process, some mild signs of dysautonomic dysfunction (nasal congestion, abnormal sweating, hypotension and fainting, excessive sleepiness, small hands and feet, and increased levels of prolactin, tiredness, and fatigue), more typical of AADC deficiency, were evaluated with new insight. Of the two AADC variants, the R347Q has already been characterized as a loss-of-function with severe catalytic impairments, while the novel L391P variant has been predicted to have a less severe impact. Bioinformatic analyses suggest that the amino acid substitution may affect affinity for the PLP coenzyme. Thus, the genotype corresponds to a phenotype with mild and late-onset symptoms, of which seizures were the clinical sign, leading to medical attention. This case report expands the spectrum of AADC deficiency phenotypes to encompass a less-disabling clinical condition including borderline cognitive functioning, drug-responsive epilepsy, and mild autonomic dysfunction.
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Affiliation(s)
- Ida Cursio
- Child Neurology and Psychiatric Unit, Pediatric Hospital G. Salesi, Azienda Ospedaliero Universitaria delle Marche, Ancona, Italy
| | - Sabrina Siliquini
- Child Neurology and Psychiatric Unit, Pediatric Hospital G. Salesi, Azienda Ospedaliero Universitaria delle Marche, Ancona, Italy
| | - Claudia Carducci
- Department of Experimental Medicine, Sapienza - Università di Roma, Rome, Italy
| | - Giovanni Bisello
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Mario Mastrangelo
- Department of Women/Child Health and Urological Science, Sapienza - Università di Roma, Rome, Italy
| | - Vincenzo Leuzzi
- Department of Human Neuroscience, Sapienza - Università di Roma, Rome, Italy
| | - Mariarita Bertoldi
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Carla Marini
- Child Neurology and Psychiatric Unit, Pediatric Hospital G. Salesi, Azienda Ospedaliero Universitaria delle Marche, Ancona, Italy
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Rizzi S, Spagnoli C, Bellini M, Cesaroni CA, Spezia E, Bergonzini P, Caramaschi E, Soliani L, Turco EC, Piccolo B, Demuth L, Cordelli DM, Biasucci G, Frattini D, Fusco C. Aromatic L-Amino-Acid Decarboxylase Deficiency Screening by Analysis of 3-O-Methyldopa in Dried Blood Spots: Results of a Multicentric Study in Neurodevelopmental Disorders. Genes (Basel) 2023; 14:1828. [PMID: 37761968 PMCID: PMC10530573 DOI: 10.3390/genes14091828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023] Open
Abstract
Aromatic L-amino acid decarboxylase deficiency (AADCd) is a rare recessive metabolic disorder caused by pathogenic homozygous or compound heterozygous variants in the dopa decarboxylase (DDC) gene. Adeno-associated viral vector-mediated gene transfer of the human DDC gene injected into the putamen is available. The typical presentation is characterized by early-onset hypotonia, severe developmental delay, movement disorders, and dysautonomia. Recently, mild and even atypical phenotypes have been reported, increasing the diagnostic challenge. The aim of this multicentric study is to identify the prevalence of AADCd in a population of patients with phenotypic clusters characterized by neurodevelopmental disorders (developmental delay/intellectual disability, and/or autism) by 3-O-methyldopa (3-OMD) detection in dried blood spots (DBS). It is essential to identify AADCd promptly, especially within non-typical phenotypic clusters, because better results are obtained when therapy is quickly started in mild-moderate phenotypes. Between 2021 and 2023, 390 patients with non-specific phenotypes possibly associated with AADCd were tested; none resulted in a positive result. This result highlights that the population to be investigated for AADCd should have more defined clinical characteristics: association with common signs (hypotonia) and/or pathognomonic symptoms (oculogyric crisis and dysautonomia). It is necessary to continue to screen selected clusters for reaching diagnosis and improving long-term outcomes through treatment initiation. This underscores the role of newborn screening in identifying AADCd.
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Affiliation(s)
- Susanna Rizzi
- Child Neurology and Psychiatry Unit, Department of Pediatrics, Presidio Ospedaliero Santa Maria Nuova, AUSL-IRCCS di Reggio Emilia, 42123 Reggio Emilia, Italy; (S.R.); (C.A.C.); (D.F.); (C.F.)
| | - Carlotta Spagnoli
- Child Neurology and Psychiatry Unit, Department of Pediatrics, Presidio Ospedaliero Santa Maria Nuova, AUSL-IRCCS di Reggio Emilia, 42123 Reggio Emilia, Italy; (S.R.); (C.A.C.); (D.F.); (C.F.)
| | - Melissa Bellini
- Pediatrics and Neonatology Unit, Maternal and Child Health Department, Guglielmo da Saliceto Hospital, 29121 Piacenza, Italy; (M.B.); (G.B.)
| | - Carlo Alberto Cesaroni
- Child Neurology and Psychiatry Unit, Department of Pediatrics, Presidio Ospedaliero Santa Maria Nuova, AUSL-IRCCS di Reggio Emilia, 42123 Reggio Emilia, Italy; (S.R.); (C.A.C.); (D.F.); (C.F.)
| | - Elisabetta Spezia
- Pediatrics Unit, Department of Pediatrics, Azienda Ospedaliero-Universitaria Policlinico di Modena, 41125 Modena, Italy; (E.S.); (P.B.); (E.C.)
| | - Patrizia Bergonzini
- Pediatrics Unit, Department of Pediatrics, Azienda Ospedaliero-Universitaria Policlinico di Modena, 41125 Modena, Italy; (E.S.); (P.B.); (E.C.)
| | - Elisa Caramaschi
- Pediatrics Unit, Department of Pediatrics, Azienda Ospedaliero-Universitaria Policlinico di Modena, 41125 Modena, Italy; (E.S.); (P.B.); (E.C.)
| | - Luca Soliani
- U.O.C. Neuropsichiatria dell’età Pediatrica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, 40138 Bologna, Italy; (L.S.); (D.M.C.)
| | - Emanuela Claudia Turco
- Child Neuropsychiatry Unit, Mother and Child Department, University-Hospital of Parma, 43126 Parma, Italy; (E.C.T.); (B.P.)
| | - Benedetta Piccolo
- Child Neuropsychiatry Unit, Mother and Child Department, University-Hospital of Parma, 43126 Parma, Italy; (E.C.T.); (B.P.)
| | - Laura Demuth
- R&D Biochemistry, Centogene GmbH, 18055 Rostock, Germany;
| | - Duccio Maria Cordelli
- U.O.C. Neuropsichiatria dell’età Pediatrica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, 40138 Bologna, Italy; (L.S.); (D.M.C.)
- Dipartimento di Scienze Mediche e Chirurgiche (DIMEC), Alma Mater Studiorum, Università di Bologna, 40138 Bologna, Italy
| | - Giacomo Biasucci
- Pediatrics and Neonatology Unit, Maternal and Child Health Department, Guglielmo da Saliceto Hospital, 29121 Piacenza, Italy; (M.B.); (G.B.)
| | - Daniele Frattini
- Child Neurology and Psychiatry Unit, Department of Pediatrics, Presidio Ospedaliero Santa Maria Nuova, AUSL-IRCCS di Reggio Emilia, 42123 Reggio Emilia, Italy; (S.R.); (C.A.C.); (D.F.); (C.F.)
| | - Carlo Fusco
- Child Neurology and Psychiatry Unit, Department of Pediatrics, Presidio Ospedaliero Santa Maria Nuova, AUSL-IRCCS di Reggio Emilia, 42123 Reggio Emilia, Italy; (S.R.); (C.A.C.); (D.F.); (C.F.)
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