1
|
Geroldi A, Ponti C, Mammi A, Patrone S, Gotta F, Trevisan L, Sanguineri F, Origone P, Gaudio A, La Barbera A, Cataldi M, Gemelli C, Massucco S, Schenone A, Lanteri P, Fiorillo C, Grandis M, Mandich P, Bellone E. Early Onset Inherited Peripheral Neuropathies: The Experience of a Specialized Referral Center for Genetic Diagnosis Achievement. Pediatr Neurol 2024; 154:4-8. [PMID: 38428336 DOI: 10.1016/j.pediatrneurol.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 01/26/2024] [Accepted: 02/05/2024] [Indexed: 03/03/2024]
Abstract
BACKGROUND Charcot-Marie-Tooth disease (CMT) is a heterogeneous group of inherited peripheral neuropathies. Although the typical disease onset is reported in the second decade, earlier onsets are not uncommon. To date, few studies on pediatric populations have been conducted and the achievement of molecular diagnosis remains challenging. METHODS During the last 24 years we recruited 223 patients with early-onset hereditary peripheral neuropathies (EOHPN), negative for PMP22 duplication, 72 of them referred by a specialized pediatric hospital. Genetic testing for CMT-associated genes has been carried out with a range of different techniques. RESULTS Of the 223 EOHPN cases, 43% were classified as CMT1 (demyelinating), 49% as CMT2 (axonal), and 8% as CMTi (intermediate). Genetic diagnosis was reached in 51% of patients, but the diagnostic yield increased to 67% when focusing only on cases from the specialized pediatric neuromuscular centers. Excluding PMP22 rearrangements, no significant difference in diagnostic rate between demyelinating and axonal forms was identified. De novo mutations account for 38% of cases. CONCLUSIONS This study describes an exhaustive picture of EOHPN in an Italian referral genetic center and analyzes the molecular diagnostic rate of a heterogeneous cohort compared with one referred by a specialized pediatric center. Our data identify MPZ, MFN2, GDAP1, and SH3TC2 genes as the most frequent players in EOHPN. Our study underlines the relevance of a specific neurological pediatric expertise to address the genetic testing and highlights its importance to clarify possible unexpected results when neuropathy is only a secondary clinical sign of a more complex phenotype.
Collapse
Affiliation(s)
- Alessandro Geroldi
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy.
| | - Clarissa Ponti
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, UOC Genetica Medica, Genoa, Italy
| | - Alessia Mammi
- IRCCS Ospedale Policlinico San Martino, UOC Genetica Medica, Genoa, Italy
| | - Serena Patrone
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
| | - Fabio Gotta
- IRCCS Ospedale Policlinico San Martino, UOC Genetica Medica, Genoa, Italy
| | - Lucia Trevisan
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, UOC Genetica Medica, Genoa, Italy
| | - Francesca Sanguineri
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, UOC Genetica Medica, Genoa, Italy
| | - Paola Origone
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, UOC Genetica Medica, Genoa, Italy
| | - Andrea Gaudio
- IRCCS Ospedale Policlinico San Martino, UOC Genetica Medica, Genoa, Italy
| | - Andrea La Barbera
- IRCCS Ospedale Policlinico San Martino, UOC Genetica Medica, Genoa, Italy
| | - Matteo Cataldi
- Pediatric Neuropsychiatric Unit, IRCCS Institute "G. Gaslini", Genoa, Italy
| | - Chiara Gemelli
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, UOC Clinica Neurologica, Genoa, Italy
| | - Sara Massucco
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, UOC Clinica Neurologica, Genoa, Italy
| | - Angelo Schenone
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, UOC Clinica Neurologica, Genoa, Italy
| | - Paola Lanteri
- Pediatric Neuropsychiatric Unit, IRCCS Institute "G. Gaslini", Genoa, Italy
| | - Chiara Fiorillo
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy; Unit of Paediatric Neurology and Neuromuscular Disorders, IRCCS Institute "G. Gaslini", Genoa, Italy
| | - Marina Grandis
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, UOC Clinica Neurologica, Genoa, Italy
| | - Paola Mandich
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, UOC Genetica Medica, Genoa, Italy
| | - Emilia Bellone
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, UOC Genetica Medica, Genoa, Italy
| |
Collapse
|
2
|
Geroldi A, Tozza S, Fiorillo C, Nolano M, Fossa P, Vitale F, Domi R, Gaudio A, Mammi A, Patrone S, Barbera AL, Origone P, Ponti C, Sanguineri F, Zara F, Cataldi M, Salpietro V, Venturi CB, Massucco S, Schenone A, Manganelli F, Mandich P, Bellone E, Gotta F. A novel de novo variant in POLR3B gene associated with a primary axonal involvement of the largest nerve fibers. J Peripher Nerv Syst 2023; 28:620-628. [PMID: 37897416 DOI: 10.1111/jns.12602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/24/2023] [Accepted: 10/25/2023] [Indexed: 10/30/2023]
Abstract
BACKGROUND AND AIMS POLR3B gene encodes a subunit of RNA polymerase III (Pol III). Biallelic mutations in POLR3B are associated with leukodystrophies, but recently de novo heterozygous mutations have been described in early onset peripheral demyelinating neuropathies with or without central involvement. Here, we report the first Italian case carrying a de novo variant in POLR3B with a pure neuropathy phenotype and primary axonal involvement of the largest nerve fibers. METHODS Nerve conduction studies, sympathetic skin response, dynamic sweat test, tactile and thermal quantitative sensory testing and brain magnetic resonance imaging were performed according to standard procedures. Histopathological examination was performed on skin and sural nerve biopsies. Molecular analysis of the proband and his relatives was performed with Next Generation Sequencing. The impact of the identified variant on the overall protein structure was evaluated through rotamers method. RESULTS Since his early adolescence, the patient presented with signs of polyneuropathy with severe distal weakness, atrophy, and reduced sensation. Neurophysiological studies showed a sensory-motor axonal polyneuropathy, with confirmed small fiber involvement. In addition, skin biopsy and sural nerve biopsy showed predominant large fibers involvement. A trio's whole exome sequencing revealed a novel de novo variant p.(Arg1046Cys) in POLR3B, which was classified as Probably Pathogenic. Molecular modeling data confirmed a deleterious effect of the variant on protein structure. INTERPRETATION Neurophysiological and morphological findings suggest a primary axonal involvement of the largest nerve fibers in POLR3B-related neuropathies. A partial loss of function mechanism is proposed for both neuropathy and leukodystrophy phenotypes.
Collapse
Affiliation(s)
- Alessandro Geroldi
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
| | - Stefano Tozza
- Department of Neuroscience, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Naples, Italy
| | - Chiara Fiorillo
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
- Child Neuropsychiatric Unit, IRCCS Institute G. Gaslini, Genoa, Italy
| | - Maria Nolano
- Department of Neuroscience, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Naples, Italy
| | - Paola Fossa
- Department of Pharmacy, University of Genoa, Genoa, Italy
| | - Floriana Vitale
- Department of Neuroscience, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Naples, Italy
| | - Regi Domi
- Department of Pharmacy, University of Genoa, Genoa, Italy
| | - Andrea Gaudio
- OU Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Alessia Mammi
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
| | - Serena Patrone
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
| | - Andrea La Barbera
- OU Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Paola Origone
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
- OU Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Clarissa Ponti
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
- OU Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Francesca Sanguineri
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
- OU Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Federico Zara
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
- Medical Genetic Unit, IRCCS Institute G. Gaslini, Genoa, Italy
| | - Matteo Cataldi
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
- Child Neuropsychiatric Unit, IRCCS Institute G. Gaslini, Genoa, Italy
| | - Vincenzo Salpietro
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
- Medical Genetic Unit, IRCCS Institute G. Gaslini, Genoa, Italy
| | | | - Sara Massucco
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
- OU Neurology Clinic, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Angelo Schenone
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
- OU Neurology Clinic, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Fiore Manganelli
- Department of Neuroscience, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Naples, Italy
| | - Paola Mandich
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
- OU Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Emilia Bellone
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genoa, Italy
- OU Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Fabio Gotta
- OU Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| |
Collapse
|