TRPM3-related neurodevelopmental disorder

Rare disease

Medical condition

TRPM3-related neurodevelopmental disorder

Specialty| Neurology

TRPM3-related neurodevelopmental disorder[1] is a monogenetic developmental and epileptic encephalopathy that affects the central nervous system.[2] The broad phenotype includes global developmental delay, intellectual disability, epilepsy, musculoskeletal anomalies, altered pain perception, ataxia, hypotonia, nystagmus, and cerebellar atrophy.[2][3][4]

## Signs and Symptoms

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The earliest sign for TRPM3-related neurodevelopmental disorder is usually congenital hypotonia. Infant feeding issues including dysphagia and gastroesophageal reflux are also reported.[1] Global developmental delay is nearly always present along with mild-to-severe intellectual disability.[1][2][4] Epilepsy is reported in 50% of cases.[1][2]

Other signs of TRPM3-related neurodevelopmental disorder are dysmorphic facial features, scoliosis, hip dysplasia, exotropia, strabismus, nystagmus, ataxia, and altered pain perception.[1][2]

## Cause

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TRPM3-related neurodevelopmental disorder is an autosomal dominant genetic disorder.[1] It is caused by missense mutations in the TRPM3 gene.[1][2] Since the general population has numerous truncating variants and microdeletions throughout TRPM3, the underlying mechanism for neurodevelopmental disorder is not haploinsufficiency.[3]

Research has shown that the disease-associated mutations lead to a gain-of-function. The mutations produce increased basal activity of the TRPM3 ion channel as well as increased response to chemical and noxious heat stimuli. The gain-of-function results in increased intracellular Ca2+. It is possible that this increased channel activity and/or Ca2+ induced nerve damage could be the underlying mechanism of the disease.[5][6][2]

## Diagnosis

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Diagnosis is made through genetic testing using an intellectual disability or epilepsy multigene panel that includes TRPM3 or whole exome sequencing.[1] Following identification of a mutation in the TRPM3 gene, alterations in channel activity are evaluated using electrophysiological assays and calcium imaging[2][6][5]

## Treatment

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There is currently no known cure or treatment for TRPM3-related neurodevelopmental disorder. Treatment for individual manifestations of symptoms may follow standard of care (anti-epileptic medication for seizures, physical therapy, occupational therapy, speech therapy, etc).[1]

A single study points to the anti-convulsant drug primidone as an off label therapeutic.[7] Primidone is a known TRPM3 antagonist.[8]

## Prognosis

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Life span is apparently not impacted by TRPM3-related neurodevelopmental disorder. Not enough data currently exists to understand the disease progression.[1]

## Epidemiology

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There are currently >30 reported cases of TRPM3-related neurodevelopmental disorder.[1][4][2][9][10][11] It is unknown what the prevalence of this disorder is worldwide.

## Other Resources

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TRPM3 Foundation

## References

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1. ^ a b c d e f g h i j k Dyment, David; Lines, Matthew; Innes, A Micheil (2023-02-23). "TRPM3-Related Neurodevelopmental Disorder". University of Washington, Seattle. PMID 36821706.
2. ^ a b c d e f g h i Burglen, Lydie; Van Hoeymissen, Evelien; Qebibo, Leila; et al. (2023). "Gain-of-function variants in the ion channel gene TRPM3 underlie a spectrum of neurodevelopmental disorders". eLife. 12. doi:10.7554/elife.81032. PMC 9886277. PMID 36648066.
3. ^ a b Dyment, David A.; Terhal, Paulien A.; Rustad, Cecilie F.; et al. (2019). "De novo substitutions of TRPM3 cause intellectual disability and epilepsy". European Journal of Human Genetics. 27 (10): 1611–1618. doi:10.1038/s41431-019-0462-x. PMC 6777445. PMID 31278393. S2CID 195804345.
4. ^ a b c Lines, Matthew A.; Goldenberg, Paula; Wong, Ashley; et al. (2022). "Phenotypic spectrum of the recurrent TRPM3 p.( Val837Met ) substitution in seven individuals with global developmental delay and hypotonia". American Journal of Medical Genetics Part A. 188 (6): 1667–1675. doi:10.1002/ajmg.a.62673. PMID 35146895. S2CID 246749002.
5. ^ a b Zhao, Siyuan; Yudin, Yevgen; Rohacs, Tibor (2020). "Disease-associated mutations in the human TRPM3 render the channel overactive via two distinct mechanisms". eLife. 9. doi:10.7554/elife.55634. PMC 7255801. PMID 32343227.
6. ^ a b Van Hoeymissen, Evelien; Held, Katharina; Nogueira Freitas, Ana Cristina; Janssens, Annelies; Voets, Thomas; Vriens, Joris (19 May 2020). "Gain of channel function and modified gating properties in TRPM3 mutants causing intellectual disability and epilepsy". eLife. 9: e57190. doi:10.7554/eLife.57190. ISSN 2050-084X. PMC 7253177. PMID 32427099.
7. ^ Becker, Lena-Luise; Horn, Denise; Boschann, Felix; et al. (2023). "Primidone improves symptoms in TRPM3-linked developmental and epileptic encephalopathy with spike-and-wave activation in sleep". Epilepsia. 64 (5): e61–e68. doi:10.1111/epi.17586. PMID 36929095. S2CID 257581570.
8. ^ Krügel, Ute; Straub, Isabelle; Beckmann, Holger; Schaefer, Michael (2017). "Primidone inhibits TRPM3 and attenuates thermal nociception in vivo". Pain. 158 (5): 856–867. doi:10.1097/j.pain.0000000000000846. PMC 5402713. PMID 28106668.
9. ^ Gauthier, LW; Chatron, N; Cabet, S; Labalme, A; Carneiro, M; Poirot, I; Delvert, C; Gleizal, A; Lesca, G; Putoux, A (November 2021). "Description of a novel patient with the TRPM3 recurrent p.Val837Met variant". European Journal of Medical Genetics. 64 (11): 104320. doi:10.1016/j.ejmg.2021.104320. PMID 34438093.
10. ^ Kang, Q; Yang, L; Liao, H; Yang, S; Kuang, X; Ning, Z; Liao, C; Chen, B (1 June 2021). "A Chinese patient with developmental and epileptic encephalopathies (DEE) carrying a TRPM3 gene mutation: a paediatric case report". BMC Pediatrics. 21 (1): 256. doi:10.1186/s12887-021-02719-8. PMC 8167971. PMID 34074259.
11. ^ Sundaramurthi, JC; Bagley, AM; Blau, H; Carmody, L; Crandall, A; Danis, D; Gargano, M; Gustafson, AG; Raney, EM; Shingle, M; Davids, JR; Robinson, PN (8 September 2023). "De novo TRPM3 missense variant associated with neurodevelopmental delay and manifestations of cerebral palsy". Cold Spring Harbor Molecular Case Studies. 9 (4): mcs.a006293. doi:10.1101/mcs.a006293. PMC 10815282. PMID 37684057. S2CID 261620692.

Classification|

* OMIM: 620224

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External resources|

* GeneReviews: TRPM3-Related Neurodevelopmental Disorder