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Phenotypic implications of pathogenic variant types in Pompe disease. J Hum Genet 2021; 66:1089-1099. [PMID: 33972680 DOI: 10.1038/s10038-021-00935-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/01/2021] [Accepted: 04/20/2021] [Indexed: 11/08/2022]
Abstract
Newborn screening and therapies for Pompe disease (glycogen storage disease type II, acid maltase deficiency) will continue to expand in the future. It is thus important to determine whether enzyme activity or type of pathogenic genetic variant in GAA can best predict phenotypic severity, particularly the presence of infantile-onset Pompe disease (IOPD) versus late-onset Pompe disease (LOPD). We performed a retrospective analysis of 23 participants with genetically-confirmed cases of Pompe disease. The following data were collected: clinical details including presence or absence of cardiomyopathy, enzyme activity levels, and features of GAA variants including exon versus intron location and splice site versus non-splice site. Several combinations of GAA variant types for individual participants had significant associations with disease subtype, cardiomyopathy, age at diagnosis, gross motor function scale (GMFS), and stability of body weight. The presence of at least one splice site variant (c.546 G > C/p.T182 = , c.1076-22 T > G, c.2646 + 2 T > A, and the classic c.-32-13T > G variant) was associated with LOPD, while the presence of non-splice site variants on both alleles was associated with IOPD. Enzyme activity levels in isolation were not sufficient to predict disease subtype or other major clinical features. To extend the findings of prior studies, we found that multiple types of splice site variants beyond the classic c.-32-13T > G variant are often associated with a milder phenotype. Enzyme activity levels continue to have utility for supporting the diagnosis when the genetic variants are ambiguous. It is important for newly diagnosed patients with Pompe disease to have complete genetic, cardiac, and neurological evaluations.
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Niño MY, Wijgerde M, de Faria DOS, Hoogeveen-Westerveld M, Bergsma AJ, Broeders M, van der Beek NAME, van den Hout HJM, van der Ploeg AT, Verheijen FW, Pijnappel WWMP. Enzymatic diagnosis of Pompe disease: lessons from 28 years of experience. Eur J Hum Genet 2020; 29:434-446. [PMID: 33162552 PMCID: PMC7940434 DOI: 10.1038/s41431-020-00752-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 10/03/2020] [Accepted: 10/20/2020] [Indexed: 11/09/2022] Open
Abstract
Pompe disease is a lysosomal and neuromuscular disorder caused by deficiency of acid alpha-glucosidase (GAA), and causes classic infantile, childhood onset, or adulthood onset phenotypes. The biochemical diagnosis is based on GAA activity assays in dried blood spots, leukocytes, or fibroblasts. Diagnosis can be complicated by the existence of pseudodeficiencies, i.e., GAA variants that lower GAA activity but do not cause Pompe disease. A large-scale comparison between these assays for patient samples, including exceptions and borderline cases, along with clinical diagnoses has not been reported so far. Here we analyzed GAA activity in a total of 1709 diagnostic cases over the past 28 years using a total of 2591 analyses and we confirmed the clinical diagnosis in 174 patients. We compared the following assays: leukocytes using glycogen or 4MUG as substrate, fibroblasts using 4MUG as substrate, and dried blood spots using 4MUG as substrate. In 794 individuals, two or more assays were performed. We found that phenotypes could only be distinguished using fibroblasts with 4MUG as substrate. Pseudodeficiencies caused by the GAA2 allele could be ruled out using 4MUG rather than glycogen as substrate in leukocytes or fibroblasts. The Asian pseudodeficiency could only be ruled out in fibroblasts using 4MUG as substrate. We conclude that fibroblasts using 4MUG as substrate provides the most reliable assay for biochemical diagnosis and can serve to validate results from leukocytes or dried blood spots.
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Affiliation(s)
- Monica Y Niño
- Department of Pediatrics, Erasmus MC University Medical Center, Rotterdam, The Netherlands.,Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands.,Center for Lysosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Mark Wijgerde
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Douglas Oliveira Soares de Faria
- Department of Pediatrics, Erasmus MC University Medical Center, Rotterdam, The Netherlands.,Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands.,Center for Lysosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | | | - Atze J Bergsma
- Department of Pediatrics, Erasmus MC University Medical Center, Rotterdam, The Netherlands.,Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands.,Center for Lysosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Mike Broeders
- Department of Pediatrics, Erasmus MC University Medical Center, Rotterdam, The Netherlands.,Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands.,Center for Lysosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Nadine A M E van der Beek
- Center for Lysosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands.,Department of Neurology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Hannerieke J M van den Hout
- Department of Pediatrics, Erasmus MC University Medical Center, Rotterdam, The Netherlands.,Center for Lysosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Ans T van der Ploeg
- Department of Pediatrics, Erasmus MC University Medical Center, Rotterdam, The Netherlands.,Center for Lysosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Frans W Verheijen
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - W W M Pim Pijnappel
- Department of Pediatrics, Erasmus MC University Medical Center, Rotterdam, The Netherlands. .,Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands. .,Center for Lysosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands.
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Nazari F, Sinaei F, Nilipour Y, Fatehi F, Streubel B, Ashrafi MR, Aryani O, Nafissi S. Late-onset pompe disease in Iran: A clinical and genetic report. Muscle Nerve 2016; 55:835-840. [PMID: 27649523 DOI: 10.1002/mus.25413] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 09/01/2016] [Accepted: 09/19/2016] [Indexed: 11/08/2022]
Abstract
INTRODUCTION Pompe disease is characterized by absence or deficiency of acid α-glucosidase, and several causative mutations are known. In this study we report clinical and laboratory data in Iranian patients with late-onset Pompe disease (LOPD), focusing on population-specific mutations. METHODS Clinical and laboratory data of 14 patients from 10 families with the diagnosis of LOPD were recorded. All had reduced enzyme activity on dried blood spot (DBS) analysis. Genetic investigation was performed to identify the underlying mutations. RESULTS The age of onset ranged from <2 to 38 years. The clinical presentations were heterogeneous. Two siblings presented with foot drop. The most common mutation was c.(-32-13T>G). There were 4 novel mutations: c.(2040 + 2dup); c.(1650delG); c.(1837T>G); and c.(2596delG). CONCLUSION This is a comprehensive report of LOPD in Iranian patients. Distinct phenotypic and genotypic features in this population are highlighted. Muscle Nerve 55: 835-840, 2017.
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Affiliation(s)
- Ferdos Nazari
- Iranian Center of Neurological Research, Shariati Hospital, Tehran University of Medical Sciences, North Karegar Street, Tehran, 14114, Iran
| | - Farnaz Sinaei
- Iranian Center of Neurological Research, Shariati Hospital, Tehran University of Medical Sciences, North Karegar Street, Tehran, 14114, Iran
| | - Yalda Nilipour
- Pediatric Pathology Research Center, Mofid Children Hospital, Shahid Beheshti Medical University, Tehran, Iran
| | - Farzad Fatehi
- Iranian Center of Neurological Research, Shariati Hospital, Tehran University of Medical Sciences, North Karegar Street, Tehran, 14114, Iran
| | - Berthold Streubel
- Department of Obstetrics and Feto-Maternal Medicine, Medical University of Vienna, Vienna, Austria
| | - Mahmoud Reza Ashrafi
- Children's Medical Center, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Omid Aryani
- Genetics Department, Special Medical Center, Tehran, Iran
| | - Shahriar Nafissi
- Iranian Center of Neurological Research, Shariati Hospital, Tehran University of Medical Sciences, North Karegar Street, Tehran, 14114, Iran
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