Spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME) is a rare autosomal recessive lysosomal disorder caused by biallelic ASAH1 variants that reduce lysosomal acid ceramidase. Impaired ceramide degradation causes ceramide accumulation and lower motor neuron and CNS neuronal dysfunction, producing a non-5q spinal muscular atrophy combined with myoclonic and generalized seizures and progressive neurological deterioration. It is allelic with Farber disease, the more severe acid ceramidase deficiency phenotype.
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Conditions with similar clinical presentations that must be differentiated from Spinal Muscular Atrophy-Progressive Myoclonic Epilepsy Syndrome:
name: Spinal Muscular Atrophy-Progressive Myoclonic Epilepsy Syndrome
creation_date: "2026-06-13T00:00:00Z"
description: >-
Spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME) is a rare autosomal
recessive lysosomal disorder caused by biallelic ASAH1 variants that reduce lysosomal acid
ceramidase. Impaired ceramide degradation causes ceramide accumulation and lower motor neuron
and CNS neuronal dysfunction, producing a non-5q spinal muscular atrophy combined with
myoclonic and generalized seizures and progressive neurological deterioration. It is allelic
with Farber disease, the more severe acid ceramidase deficiency phenotype.
synonyms:
- SMA-PME
- ASAH1-related spinal muscular atrophy with progressive myoclonic epilepsy
- acid ceramidase deficiency, SMA-PME phenotype
- Jankovic syndrome
category: Mendelian
disease_term:
preferred_term: spinal muscular atrophy-progressive myoclonic epilepsy syndrome
term:
id: MONDO:0008045
label: spinal muscular atrophy-progressive myoclonic epilepsy syndrome
mappings:
mondo_mappings:
- term:
id: MONDO:0008045
label: spinal muscular atrophy-progressive myoclonic epilepsy syndrome
mapping_predicate: skos:exactMatch
mapping_source: MONDO
parents:
- Lysosomal Storage Disorder
inheritance:
- name: Autosomal recessive
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
evidence:
- reference: PMID:37280710
reference_title: "Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME): three new cases and review of the mutational spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "A rare form of non-5q SMA\nis an autosomal-recessive condition called spinal muscular atrophy with\nprogressive myoclonic epilepsy (SMA-PME)"
explanation: SMA-PME is an autosomal recessive non-5q SMA.
pathophysiology:
- name: Acid Ceramidase Deficiency
conforms_to: "lysosomal_substrate_accumulation#Lysosomal Hydrolase or Cofactor Deficiency"
description: >-
Biallelic ASAH1 variants reduce lysosomal acid ceramidase, the hydrolase that degrades
ceramide; SMA-PME is allelic with Farber disease.
gene:
preferred_term: ASAH1
term:
id: hgnc:735
label: ASAH1
biological_processes:
- preferred_term: ceramide catabolic process
term:
id: GO:0046514
label: ceramide catabolic process
modifier: DECREASED
evidence:
- reference: PMID:40017560
reference_title: "Acid Ceramidase Deficiency: New Insights on SMA-PME Natural History, Biomarkers, and In Cell Enzyme Activity Assay."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "epilepsy (SMA-PME) due to acid ceramidase deficiency is a rare disorder, allelic\nwith Farber disease, resulting from recessive ASAH1 variants"
explanation: SMA-PME results from acid ceramidase deficiency due to recessive ASAH1 variants, allelic with Farber disease.
downstream:
- target: Ceramide Accumulation and Motor Neuron Degeneration
description: Reduced ceramide degradation causes ceramide accumulation and neuronal injury.
- name: Ceramide Accumulation and Motor Neuron Degeneration
conforms_to: "lysosomal_substrate_accumulation#Lysosomal Substrate Accumulation"
description: >-
Impaired ceramide degradation causes ceramide accumulation, driving lower motor neuron loss
(spinal muscular atrophy) and cortical neuronal dysfunction (progressive myoclonic epilepsy).
cell_types:
- preferred_term: motor neuron
term:
id: CL:0000100
label: motor neuron
- preferred_term: neuron
term:
id: CL:0000540
label: neuron
evidence:
- reference: PMID:37280710
reference_title: "Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME): three new cases and review of the mutational spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "myoclonic and generalized seizures with progressive neurological deterioration"
explanation: Ceramide-driven neuronal dysfunction produces seizures and progressive neurological deterioration.
downstream:
- target: Spinal muscular atrophy
causal_link_type: DIRECT
description: >-
Lower motor neuron degeneration produces the spinal muscular atrophy
component of SMA-PME.
evidence:
- reference: PMID:37280710
reference_title: "Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME): three new cases and review of the mutational spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "spinal muscular atrophy with\nprogressive myoclonic epilepsy (SMA-PME)"
explanation: The review names spinal muscular atrophy as the motor-neuron component of SMA-PME.
- target: Muscle weakness
causal_link_type: DIRECT
description: >-
Anterior horn and lower motor neuron involvement produces progressive
muscle weakness.
evidence:
- reference: PMID:40017560
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Patients present\nin early childhood with muscle weakness due to anterior horn degeneration"
explanation: The natural-history report directly links muscle weakness to anterior horn degeneration.
- target: Myoclonic seizures
causal_link_type: DIRECT
description: >-
Cortical neuronal dysfunction produces myoclonic seizures.
evidence:
- reference: PMID:37280710
reference_title: "Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME): three new cases and review of the mutational spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "myoclonic and generalized seizures with progressive neurological deterioration"
explanation: The review lists myoclonic seizures as part of the progressive neurologic phenotype.
- target: Generalized seizures
causal_link_type: DIRECT
description: >-
Cortical neuronal dysfunction also produces generalized seizures in
SMA-PME.
evidence:
- reference: PMID:37280710
reference_title: "Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME): three new cases and review of the mutational spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "myoclonic and generalized seizures with progressive neurological deterioration"
explanation: The review lists generalized seizures as part of the progressive neurologic phenotype.
- target: Drug-resistant myoclonic epilepsy
causal_link_type: DIRECT
description: >-
Progressive neuronal dysfunction manifests as drug-resistant myoclonic
epilepsy in the SMA-PME spectrum.
evidence:
- reference: PMID:40017560
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "and/or\nprogressive drug-resistant myoclonic epilepsy"
explanation: The natural-history report identifies progressive drug-resistant myoclonic epilepsy as a core presentation.
phenotypes:
- name: Spinal muscular atrophy
description: Lower motor neuron degeneration producing progressive proximal weakness (non-5q SMA).
phenotype_term:
preferred_term: Spinal muscular atrophy
term:
id: HP:0007269
label: Spinal muscular atrophy
evidence:
- reference: PMID:37280710
reference_title: "Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME): three new cases and review of the mutational spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "spinal muscular atrophy with\nprogressive myoclonic epilepsy (SMA-PME)"
explanation: Spinal muscular atrophy is the motor component of SMA-PME.
- name: Myoclonic seizures
description: Myoclonic seizures characterize the progressive myoclonic epilepsy component.
phenotype_term:
preferred_term: Myoclonic seizure
term:
id: HP:0032794
label: Myoclonic seizure
evidence:
- reference: PMID:37280710
reference_title: "Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME): three new cases and review of the mutational spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "myoclonic and generalized seizures with progressive neurological deterioration"
explanation: Myoclonic seizures are a defining feature of SMA-PME.
- name: Generalized seizures
description: Generalized seizures accompany the myoclonic epilepsy.
phenotype_term:
preferred_term: Generalized-onset seizure
term:
id: HP:0002197
label: Generalized-onset seizure
evidence:
- reference: PMID:37280710
reference_title: "Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME): three new cases and review of the mutational spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "myoclonic and generalized seizures with progressive neurological deterioration"
explanation: Generalized seizures occur in SMA-PME.
- name: Muscle weakness
description: Progressive muscle weakness from lower motor neuron loss.
phenotype_term:
preferred_term: Muscle weakness
term:
id: HP:0001324
label: Muscle weakness
clinical_course: PROGRESSIVE
evidence:
- reference: PMID:40017560
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Patients present\nin early childhood with muscle weakness due to anterior horn degeneration"
explanation: Muscle weakness in SMA-PME results from anterior horn (lower motor neuron) degeneration, presenting in early childhood.
- name: Drug-resistant myoclonic epilepsy
description: Progressive drug-resistant myoclonic epilepsy is a core component of SMA-PME.
phenotype_term:
preferred_term: Myoclonic seizure
term:
id: HP:0032794
label: Myoclonic seizure
evidence:
- reference: PMID:40017560
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "and/or\nprogressive drug-resistant myoclonic epilepsy"
explanation: The myoclonic epilepsy of SMA-PME is progressive and drug-resistant.
- name: Sensorineural hearing loss
description: >-
Sensorineural hearing loss occurs in a majority of SMA-PME patients per the Cuinat 2025
natural-history cohort (per-patient frequency in full text).
phenotype_term:
preferred_term: Sensorineural hearing impairment
term:
id: HP:0000407
label: Sensorineural hearing impairment
evidence:
- reference: ORPHA:2590
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0000407 | Sensorineural hearing impairment | Occasional (29-5%)"
explanation: Orphadata lists sensorineural hearing impairment as an occasional SMA-PME phenotype.
- name: Cognitive impairment
description: >-
Cognitive impairment is reported in a substantial fraction of SMA-PME patients (Cuinat
2025 cohort; full-text frequency data).
phenotype_term:
preferred_term: Cognitive impairment
term:
id: HP:0100543
label: Cognitive impairment
biochemical:
- name: Reduced acid ceramidase activity and elevated C26-ceramide
presence: DECREASED
context: >-
Reduced acid ceramidase (ACDase) activity with elevated C26-ceramide measurable on dried
blood spots is a diagnostic biomarker; an in-cell ceramide-degradation assay supports it.
evidence:
- reference: PMID:40017560
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "C26-ceramide\nquantification on dried blood spots (DBSs) was performed"
explanation: C26-ceramide quantification on dried blood spots is a usable diagnostic biomarker.
genetic:
- name: ASAH1 pathogenic variants
gene_term:
preferred_term: ASAH1
term:
id: hgnc:735
label: ASAH1
association: Causative
notes: >-
Biallelic ASAH1 variants cause SMA-PME; recurrent exon 2 missense variants
(e.g., c.109C>A p.Pro37Thr, c.125C>T p.Thr42Met) have been reported.
evidence:
- reference: PMID:37280710
reference_title: "Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME): three new cases and review of the mutational spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "two different homozygous missense mutations"
explanation: Recurrent exon 2 ASAH1 missense variants cause SMA-PME.
diagnosis:
- name: ASAH1 sequencing and ceramidase assay
description: >-
Diagnosis is established by ASAH1 molecular testing (after excluding 5q SMA by SMN1/SMN2
analysis) and demonstration of reduced acid ceramidase activity / elevated C26-ceramide.
diagnosis_term:
preferred_term: genetic testing
term:
id: MAXO:0000127
label: genetic testing
evidence:
- reference: PMID:37280710
reference_title: "Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME): three new cases and review of the mutational spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "whole-exome\nsequencing was performed to detect the disease-causing variants in three cases\nof SMA-PME"
explanation: Exome/ASAH1 sequencing establishes the SMA-PME diagnosis after excluding 5q SMA.
differential_diagnoses:
- name: Farber disease
description: >-
Farber disease (Farber lipogranulomatosis) is the more severe acid ceramidase deficiency
phenotype, allelic with SMA-PME, presenting with subcutaneous nodules, arthropathy, and
hoarseness rather than the SMA/myoclonic epilepsy picture.
disease_term:
preferred_term: Farber lipogranulomatosis
term:
id: MONDO:0009218
label: Farber lipogranulomatosis
evidence:
- reference: PMID:40017560
reference_title: "Acid Ceramidase Deficiency: New Insights on SMA-PME Natural History, Biomarkers, and In Cell Enzyme Activity Assay."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "due to acid ceramidase deficiency is a rare disorder, allelic\nwith Farber disease"
explanation: SMA-PME and Farber disease are allelic acid ceramidase deficiency phenotypes.
- name: 5q spinal muscular atrophy
description: >-
Classic 5q SMA (SMN1) presents with proximal weakness but without myoclonic epilepsy and
is excluded by SMN1/SMN2 copy-number analysis.
evidence:
- reference: PMID:37280710
reference_title: "Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME): three new cases and review of the mutational spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Multiplex ligation-dependent probe\namplification (MLPA) was employed for determining the copy numbers of SMN1 and\nSMN2 genes to rule out 5q SMA"
explanation: SMN1/SMN2 analysis distinguishes SMA-PME (non-5q) from classic 5q SMA.
treatments:
- name: Supportive and Antiepileptic Care
description: >-
No disease-modifying therapy exists; management is supportive, including antiepileptic
drugs for myoclonic/generalized seizures and respiratory/neuromuscular support.
treatment_term:
preferred_term: supportive care
term:
id: MAXO:0000950
label: supportive care
evidence:
- reference: PMID:37280710
reference_title: "Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME): three new cases and review of the mutational spectrum."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "myoclonic and generalized seizures with progressive neurological deterioration"
explanation: This is phenotype evidence (drug-resistant seizures) motivating the supportive antiepileptic approach; no disease-modifying therapy exists.
references:
- reference: PMID:40017560
title: "Acid Ceramidase Deficiency: New Insights on SMA-PME Natural History, Biomarkers, and In Cell Enzyme Activity Assay."
Spinal muscular atrophy with progressive myoclonic epilepsy (SMA‑PME) is an ultra-rare, autosomal recessive, non‑5q spinal muscular atrophy phenotype characterized by lower motor neuron degeneration (anterior horn cell disease) with progressive muscle weakness plus progressive myoclonic epilepsy and neurologic deterioration. It is caused by biallelic loss‑of‑function variants in ASAH1, encoding lysosomal acid ceramidase (ACDase), and is allelic to Farber disease (acid ceramidase deficiency spectrum). (cuinat2025acidceramidasedeficiency pages 1-2, najafi2023spinalmuscularatrophy pages 1-2)
Direct abstract quotes supporting the definition include: - “Spinal muscular atrophy with progressive myoclonic epilepsy (SMA‑PME) due to acid ceramidase deficiency is a rare disorder, allelic with Farber disease, resulting from recessive ASAH1 variants.” (Cuinat et al., 2025-04; https://doi.org/10.1212/nxg.0000000000200243) (cuinat2025acidceramidasedeficiency pages 1-2) - “Patients present in early childhood with muscle weakness due to anterior horn degeneration and/or progressive drug-resistant myoclonic epilepsy.” (Cuinat et al., 2025-04; https://doi.org/10.1212/nxg.0000000000200243) (cuinat2025acidceramidasedeficiency pages 1-2)
The retrieved evidence is derived from aggregated disease resources: case reports/series, mutational spectrum reviews, natural history synthesis, and clinical trial registry entries—not from EHR-only sources in this retrieval set. (cuinat2025acidceramidasedeficiency pages 1-2, najafi2023spinalmuscularatrophy pages 2-4, NCT03233841 chunk 1)
| Concept (disease/gene/enzyme) | Identifier type | Identifier/value | Notes/synonyms | Evidence snippet (short quote) | Source (authors year, URL) |
|---|---|---|---|---|---|
| Disease | Preferred name | Spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME) | Also written as “spinal muscular atrophy with progressive myoclonic epilepsy”; ASAH1-related acid ceramidase deficiency phenotype | “Spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME)” (cuinat2025acidceramidasedeficiency pages 1-2, najafi2023spinalmuscularatrophy pages 1-2) | Cuinat et al. 2025, https://doi.org/10.1212/nxg.0000000000200243; Najafi et al. 2023, https://doi.org/10.1186/s13052-023-01474-z |
| Disease | OMIM/MIM | MIM #159950 | Explicitly given for SMA-PME | “SMA-PME (MIM#159950)” (cuinat2025acidceramidasedeficiency pages 1-2) | Cuinat et al. 2025, https://doi.org/10.1212/nxg.0000000000200243 |
| Disease | Disease classification / related disorder | Acid ceramidase deficiency | SMA-PME is described as an ASAH1-related acid ceramidase deficiency disorder allelic with Farber disease | “SMA-PME due to acid ceramidase deficiency is a rare disorder, allelic with Farber disease” (cuinat2025acidceramidasedeficiency pages 1-2) | Cuinat et al. 2025, https://doi.org/10.1212/nxg.0000000000200243 |
| Disease | Related disease OMIM/MIM | Farber disease (FD; MIM #228000) | Allelic disorder within ASAH1 deficiency spectrum | “Farber disease (FD; MIM#228000) and SMA-PME (MIM#159950)” (cuinat2025acidceramidasedeficiency pages 1-2) | Cuinat et al. 2025, https://doi.org/10.1212/nxg.0000000000200243 |
| Disease | MONDO | Not in retrieved sources | No MONDO identifier explicitly stated in retrieved evidence | “The excerpt does not provide Orphanet, MONDO, MeSH, or ICD codes.” (cuinat2025acidceramidasedeficiency pages 1-2) | Cuinat et al. 2025, https://doi.org/10.1212/nxg.0000000000200243 |
| Disease | Orphanet | Not in retrieved sources | No Orphanet identifier explicitly stated in retrieved evidence | “The excerpt does not provide Orphanet, MONDO, MeSH, or ICD codes.” (cuinat2025acidceramidasedeficiency pages 1-2) | Cuinat et al. 2025, https://doi.org/10.1212/nxg.0000000000200243 |
| Disease | MeSH | Not in retrieved sources | No MeSH identifier explicitly stated in retrieved evidence | “The excerpt does not provide Orphanet, MONDO, MeSH, or ICD codes.” (cuinat2025acidceramidasedeficiency pages 1-2) | Cuinat et al. 2025, https://doi.org/10.1212/nxg.0000000000200243 |
| Disease | ICD-10/ICD-11 | Not in retrieved sources | No ICD code explicitly stated in retrieved evidence | “The excerpt does not provide Orphanet, MONDO, MeSH, or ICD codes.” (cuinat2025acidceramidasedeficiency pages 1-2) | Cuinat et al. 2025, https://doi.org/10.1212/nxg.0000000000200243 |
| Gene | Gene symbol | ASAH1 | Causative gene for SMA-PME; recessive biallelic pathogenic variants | “biallelic pathogenic variants in ASAH1 gene” (najafi2023spinalmuscularatrophy pages 1-2) | Najafi et al. 2023, https://doi.org/10.1186/s13052-023-01474-z |
| Gene | Full gene/protein name | N-acylsphingosine amidohydrolase 1 (ASAH1) | Gene encodes lysosomal acid ceramidase | “encodes N-Acylsphingosine Amidohydrolase 1 (ASAH1)” (nishio2024clinicalandgenetic pages 19-21, nishio2024clinicalandgenetic pages 21-22) | Nishio et al. 2024, https://doi.org/10.3390/genes15101294 |
| Gene | Chromosomal location | 8p22 | Explicitly stated in retrieved evidence | “ASAH1 (14 exons, located at 8p22)” (najafi2023spinalmuscularatrophy pages 1-2) | Najafi et al. 2023, https://doi.org/10.1186/s13052-023-01474-z |
| Gene | Alternative cytogenetic location wording | 8p23.3–p21.3 | Alternate location wording reported in review | “mapped to chromosome 8p23.3–p21.3” (nishio2024clinicalandgenetic pages 19-21) | Nishio et al. 2024, https://doi.org/10.3390/genes15101294 |
| Enzyme/protein | Enzyme name | Acid ceramidase (ACDase; aCDase) | Lysosomal hydrolase encoded by ASAH1; synonyms ACDase/aCDase | “ASAH1 encodes acid ceramidase (aCDase)” (najafi2023spinalmuscularatrophy pages 1-2); “ACDase (acid ceramidase)” (cuinat2025acidceramidasedeficiency pages 1-2) | Najafi et al. 2023, https://doi.org/10.1186/s13052-023-01474-z; Cuinat et al. 2025, https://doi.org/10.1212/nxg.0000000000200243 |
| Disease information source type | Evidence provenance | Aggregated disease-level literature/case series; not EHR-derived in retrieved sources | Retrieved evidence consists of case reports, case series, reviews, and a natural history study | “we present the detailed history of 9 patients… Based on a comprehensive literature review” (cuinat2025acidceramidasedeficiency pages 1-2); “three new cases and review of the mutational spectrum” (najafi2023spinalmuscularatrophy pages 2-4) | Cuinat et al. 2025, https://doi.org/10.1212/nxg.0000000000200243; Najafi et al. 2023, https://doi.org/10.1186/s13052-023-01474-z |
Table: This table summarizes the explicitly stated disease, gene, and enzyme identifiers and nomenclature retrieved for ASAH1-related spinal muscular atrophy with progressive myoclonic epilepsy. It is useful for normalization of disease knowledge base entries while clearly marking identifiers that were not available in the retrieved evidence.
SMA‑PME is caused by biallelic pathogenic variants in ASAH1, producing acid ceramidase deficiency with downstream ceramide accumulation. (cuinat2025acidceramidasedeficiency pages 1-2, najafi2023spinalmuscularatrophy pages 1-2)
Mechanistic definition quote: - Acid ceramidase “catalyzes the degradation of ceramides into fatty acids and sphingosine inside the lysosome.” (Cuinat et al., 2025-04; https://doi.org/10.1212/nxg.0000000000200243) (cuinat2025acidceramidasedeficiency pages 1-2)
Across recent case series/reviews, core manifestations include: - Motor neuron disease / SMA phenotype: progressive proximal weakness, gait loss, muscle atrophy, tremor; attributed to anterior horn degeneration. (cuinat2025acidceramidasedeficiency pages 1-2, najafi2023spinalmuscularatrophy pages 2-4) - Progressive myoclonic epilepsy: myoclonus and generalized seizures (including tonic‑clonic, absences, drop attacks), often progressively drug‑resistant. (cuinat2025acidceramidasedeficiency pages 2-3, najafi2023spinalmuscularatrophy pages 2-4) - Neurodevelopment/cognition: cognitive impairment and psychomotor regression can appear later in disease in a subset (e.g., cognitive impairment 4/9; psychomotor regression 3/9 in one cohort). (cuinat2025acidceramidasedeficiency pages 3-4) - Sensorineural hearing loss: reported frequently in one cohort (5/9). (cuinat2025acidceramidasedeficiency pages 2-3)
Recent natural history statistics (Cuinat et al. 2025; 9 new patients + literature review): - “A total of 44 patients from 37 families.” (cuinat2025acidceramidasedeficiency pages 2-3) - “Age at onset ranged from 2.5 to 16 years” and epilepsy onset typically “5 to 14 years.” (cuinat2025acidceramidasedeficiency pages 8-10) - In the 9-patient cohort: weakness in 8/9 (mean ~10 years), loss of ambulation 5/9 (mean ~12.6 years), epilepsy 7/9 (mean ~9.7 years), drug resistance 4/7 occurring ~1.1 years after onset. (cuinat2025acidceramidasedeficiency pages 2-3) - Mortality: “50% of patients died before 18 years” and death “at around 17 years of age,” typically from respiratory complications or status epilepticus. (cuinat2025acidceramidasedeficiency pages 8-10, cuinat2025acidceramidasedeficiency pages 1-2)
(ontology mappings suggested for knowledge-base use) - Proximal muscle weakness (HP:0008994) - Muscle atrophy (HP:0003202) - Lower motor neuron dysfunction / neurogenic muscle weakness (HP:0007340, motor neuron phenotype terms) - Myoclonic seizures (HP:0002123) - Generalized tonic-clonic seizures (HP:0002069) - Progressive myoclonic epilepsy (HP:0007256) - Drug-resistant epilepsy (HP:0002340) - Tremor (HP:0001337) - Loss of ambulation (HP:0031936) - Sensorineural hearing impairment (HP:0000407) - Cognitive impairment (HP:0100543) - Developmental regression (HP:0002376)
While formal QoL instruments were not reported in the retrieved papers, the progressive loss of gait/ambulation, drug-resistant epilepsy, and cognitive regression imply major functional impairment. Motor scales (MFM‑32; GMFC‑MLD) were used in prospective follow-up in SMA‑PME, indicating clinically meaningful monitoring of function. (cuinat2025acidceramidasedeficiency pages 1-2)
Genotype–phenotype signals (from compiled case analysis): - Two variants recur in the literature synthesis (e.g., p.(Thr42Met) and p.(Lys152Asn)) and were associated with differences in onset; the 2025 natural history study reports a “genotype-phenotype correlation for the 2 main variants and the disease onset.” (cuinat2025acidceramidasedeficiency pages 1-2) - Variant distribution across ACDase subunits: Farber-associated mutations cluster more in the β-subunit, whereas “a larger number of mutations in SMA‑PME have been identified within the alpha-subunit.” (nishio2024clinicalandgenetic pages 19-21, nishio2024clinicalandgenetic pages 21-22) - “Residual levels of acid ceramidase activity may determine the phenotype of the ASAH1-related disorders.” (nishio2024clinicalandgenetic pages 21-22)
No SMA‑PME-specific human modifier-gene or epigenetic evidence was retrieved in the current tool run.
No SMA‑PME-specific environmental, lifestyle, or infectious contributing factors were identified in the retrieved evidence; this disorder is primarily Mendelian (ASAH1). (cuinat2025acidceramidasedeficiency pages 1-2, najafi2023spinalmuscularatrophy pages 1-2)
ASAH1 loss of function → reduced lysosomal acid ceramidase activity → ceramide accumulation in tissues (CNS and peripheral organs) → inflammatory responses and neurodegeneration/motor neuron pathology → progressive weakness (SMA phenotype) and progressive myoclonic epilepsy. (cuinat2025acidceramidasedeficiency pages 1-2, derome2024[therapeuticperspectivesfor pages 2-3)
Mechanistic tissue distribution quote (French review): - “Cette mutation empêche l’adressage de l’ACDase au lysosome, réduit son activité enzymatique et entraîne une accumulation de céramides dans le cerveau et les organes périphériques…” (Derome et al., 2024-11; https://doi.org/10.1051/medsci/2024162) (derome2024[therapeuticperspectivesfor pages 2-3) - “Les niveaux de céramides sont élevés dans le SNC, de manière plus importante dans la moelle épinière que dans le cerveau.” (derome2024[therapeuticperspectivesfor pages 2-3)
Neuroinflammation hypothesis (review): - “Accumulation of ceramide may also cause an imbalanced activation of pathways and mediators in microglia, leading to neurodegeneration and neuroinflammation.” (Nishio et al., 2024-09; https://doi.org/10.3390/genes15101294) (nishio2024clinicalandgenetic pages 19-21)
A 2024 review summarizes zebrafish ASAH1 knockdown phenotypes: “marked loss of motor-neuron axonal branching and increased spinal-cord apoptosis,” supporting motor neuron vulnerability to ASAH1 deficiency. (nishio2024clinicalandgenetic pages 21-22)
Mouse model survival statistics (therapeutic perspectives review): - Asah1P361R/P361R (Farber-like) median survival “autour de 50 jours” and a milder line with median survival “145 jours.” (derome2024[therapeuticperspectivesfor pages 2-3)
The 2025 natural history synthesis describes a progressive course with development of weakness and epilepsy, loss of ambulation, later cognitive decline in some, and adolescent mortality in many. (cuinat2025acidceramidasedeficiency pages 8-10, cuinat2025acidceramidasedeficiency pages 2-3, cuinat2025acidceramidasedeficiency pages 1-2)
Disease prevalence is not robustly established in the retrieved primary sources. A 2024 French-language review states ASAH1 deficiency prevalence is “<1/1,000,000.” (derome2024[therapeuticperspectivesfor pages 1-2)
Consanguinity and homozygosity are prominent in reported cases (55% homozygous variants; 42% parental consanguinity reported). (cuinat2025acidceramidasedeficiency pages 8-10)
Testing-strategy evidence in non‑5q SMA cohorts (actionable for SMA‑PME differential): - Theuriet et al. recommend “a large NGS panel should be the first choice, before performing WES or WGS,” and note ASAH1 was missed because it was not included in the panel: “the ASAH1 variant could not have been detected by the NGS panel, because this gene is currently not included,” prompting the recommendation to update panels to include ASAH1. (Theuriet et al., 2024-06; https://doi.org/10.1038/s41431-023-01407-8) (theuriet2024geneticcharacterizationof pages 6-7)
SMA‑PME is associated with EEG abnormalities (e.g., generalized spikes and slow waves; generalized SW/PSW complexes), and neurogenic changes on muscle biopsy/EMG consistent with denervation in cited case series summarized in the 2024 non‑5q SMA review. (nishio2024clinicalandgenetic pages 19-21, nishio2024clinicalandgenetic pages 21-22)
Key laboratory measures in recent natural-history work include: - ACDase activity in leukocytes: profoundly decreased (e.g., “1.5%–8.3% of control values” in one cohort). (cuinat2025acidceramidasedeficiency pages 2-3) - C26‑ceramide on dried blood spots (DBS) by LC‑MS/MS: evaluated as a candidate biomarker; authors note limited reliability for longitudinal follow-up in SMA‑PME (moderate accumulation; variable trajectories). (cuinat2025acidceramidasedeficiency pages 12-13) - In-cell ceramide degradation assay in living skin fibroblasts: proposed as a more reliable measure of residual enzymatic activity and a potential pharmacodynamic readout for therapy. (cuinat2025acidceramidasedeficiency pages 1-2)
SMA‑PME has a poor prognosis with progressive neurologic decline. In compiled analyses, death is often in adolescence, frequently due to respiratory complications or status epilepticus; one synthesis reports that “50% of patients died before 18 years” and death “at around 17 years of age.” (cuinat2025acidceramidasedeficiency pages 8-10, cuinat2025acidceramidasedeficiency pages 1-2)
No disease-modifying or curative treatment is established in the retrieved evidence; management is largely supportive and symptomatic. - Najafi et al. state that “No successful disease-modifying treatments have been reported; management is symptomatic and multidisciplinary.” (najafi2023spinalmuscularatrophy pages 2-4) - A 2024 therapeutic perspectives review states: “À ce jour, il n’y a pas de traitement spécifique ou curatif disponible.” (Derome et al., 2024-11; https://doi.org/10.1051/medsci/2024162) (derome2024[therapeuticperspectivesfor pages 1-2)
Because SMA‑PME is on the ASAH1 (acid ceramidase deficiency) spectrum, therapeutic concepts often derive from Farber disease and lysosomal storage disease strategies: - Hematopoietic stem cell transplantation (HSCT): reported to correct peripheral inflammatory signs but not neurologic progression in acid ceramidase deficiency: “correction complète et persistante des signes inflammatoires… mais n’empêche pas la progression de la maladie neurologique.” (derome2024[therapeuticperspectivesfor pages 2-3) - Enzyme replacement therapy (ERT; rhACDase): preclinical ERT lowers ceramide accumulation and inflammatory markers in Asah1 mutant mice; a key limitation is CNS penetration (“does not yet have the full capacity to penetrate the blood–brain barrier”). (Kleynerman et al., 2023-02; https://doi.org/10.3390/biom13020274) (kleynerman2023acidceramidasedeficiency pages 14-15) - Gene therapy / gene-based approaches: discussed conceptually as promising for sphingolipid metabolic disorders and acid ceramidase deficiency in expert reviews; AAV-based delivery and lentiviral HSC gene therapy frameworks are described as potential strategies. (derome2024[therapeuticperspectivesfor pages 2-3, kleynerman2023acidceramidasedeficiency pages 14-15)
While no SMA‑PME interventional trials were retrieved in this run, Farber disease (same ASAH1/ACDase deficiency spectrum) has structured observational studies relevant to biomarker and outcome development: - Farber Disease Natural History Study (NCT03233841; completed; enrollment 45; first posted 2017): collects clinical/functional outcomes (6MWT, PFTs), PROs, imaging, inflammatory markers, and exploratory “specific ceramide levels” and “cytokines/chemokines” in blood; confirmatory diagnosis includes acid ceramidase activity <30% of control. https://clinicaltrials.gov/study/NCT03233841 (NCT03233841 chunk 1) - BioFarber biomarker study (NCT02298634; withdrawn; first posted 2018): planned NGS confirmation of ASAH1 and mass‑spectrometry biomarker discovery from DBS. https://clinicaltrials.gov/study/NCT02298634 (NCT02298634 chunk 1)
Primary prevention is not applicable in the traditional (environmental) sense for a recessive Mendelian disorder, but genetic counseling and carrier testing in affected families are central.
Given recessive inheritance and high consanguinity fraction reported, preventive strategies include cascade testing and reproductive counseling. (cuinat2025acidceramidasedeficiency pages 8-10)
No naturally occurring veterinary disease analogs were retrieved in the current evidence set.
Model-organism work is substantial for acid ceramidase deficiency broadly: - Mouse models (e.g., Asah1P361R/P361R) recapitulate systemic ceramide accumulation, inflammation, and early mortality (median survival ~50 days in one model; 145 days in a milder line). (derome2024[therapeuticperspectivesfor pages 2-3) - Zebrafish knockdown evidence suggests motor neuron axonal branching defects and spinal cord apoptosis. (nishio2024clinicalandgenetic pages 21-22)
References
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