Adult onset neurodegenerative disorder

Gene: ARSA

Green List (high evidence)

Comment on mode of inheritance: ARSA deficiency is a well-established cause of recessive metachromatic leukodystrophy. There is also some emerging evidence that heterozygous variants in ARSA may be a genetic modifier of Parkinson's disease. However, heterozygous variants act as risk factors, rather than causing familial dominant disease. Hence, the mode of inheritance should remain as 'BIALLELIC, autosomal or pseudoautosomal' on this panel.

Created: 8 Jul 2026, 9:45 a.m. | Last Modified: 8 Jul 2026, 9:45 a.m.

Panel Version: 9.2

PMID: 37381728 Senkevich et al., 2023
Authors performed burden analyses in six independent cohorts with 5801 PD patients and 20,475 controls, followed by meta-analysis, and found evidence for associations between rare functional ARSA variants and PD in four cohorts (P ≤ 0.05 in each). Of note: "results should be interpreted with caution as no association survived multiple comparisons correction."

Authors also found potential co-segregation of p.E382K variant in two unrelated PD patients with history of MLD and PD. The variant was not found in any controls.
Family A, patient II-4 - 62yo, had Parkinson's disease, het for p.E382K; also a carrier of the GBA1 variant RecNcil - hence, impossible to estimate the role of the ARSA variant in PD.
Family A, individual IV-1 - 12yo, diagnosed with MLD, comp het for ARSA variants p.E382K and c.465G>T, p.Q155H.
Caveat: variant p.E382K = c.1150G>A, p.Glu384Lys (p.E384K) - MAF = 0.00005331 in gnomAD v4.1.1., no homozygotes. P/LP classification in ClinVar.
Family B: 5 family members with Parkinson's disease, 4 deceased and not genotyped (77-82yrs), individual II-4 (72yo) had PD and was ARSA wt/wt. Individual IV-1: 7yo, MLD diagnosis, comp het for ARSA variants p.E382K and c.1107+1G>A. Other het p.E382K carriers are aged under 60yo so not known if they will be affected by PD.

PMID: 31312839 Lee et al., 2019
Reported a 32yo female proband with MLD, comp het for ARSA variants p.L300S and p.C174Y. Her father and paternal uncle had Parkinson's disease, and were heterozygous for the ARSA p.L300S variant - thought to be a potential risk factor.
Also analysed 92 cases with familial dominant Parkinson's disease. ARSA p.N352S was found to be a protective variant (more common in controls than PD cohort).
"ARSA is a genetic modifier of Parkinson's disease pathogenesis, acting as a molecular chaperone for α-synuclein." In cell lines, authors showed that ARSA deficiency correlates with an increase in α-synuclein aggregation.

Created: 8 Jul 2026, 9:41 a.m. | Last Modified: 8 Jul 2026, 9:57 a.m.

Panel Version: 9.2

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Metachromatic leukodystrophy, OMIM:250100; metachromatic leukodystrophy, MONDO:0018868; arylsulfatase A deficiency

Publications

• 31312839
• 37381728

Green List (high evidence)

metachromatic leukodystrophies comprise several allelic disorders.In the late infantile form, onset is usually in the second year of life and death occurs before 5 years in most. Clinical features are motor symptoms, rigidity, mental deterioration, and sometimes convulsions. In the adult form of metachromatic leukodystrophy, initial symptoms, which begin after age 16, are usually psychiatric and may lead to a diagnosis of schizophrenia. Disorders of movement and posture appear late. Can be diagnosed biochemically - low ASA activity. Many cases.

Created: 2 Sep 2019, 4:06 p.m. | Last Modified: 2 Sep 2019, 4:06 p.m.

Panel Version: 1.99

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Metachromatic leukodystrophy (#250100); Dystonia

Green List (high evidence)

Adult onset form reported.

Created: 23 Jul 2019, 3:35 p.m. | Last Modified: 23 Jul 2019, 3:35 p.m.

Panel Version: 1.72

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Metachromatic leukodystrophy (#250100); Dystonia

Variants in this GENE are reported as part of current diagnostic practice

I don't know

Review and rating from Tracy Lester (Oxford Medical Genetics Laboratories Oxford University Hospitals NHS Foundation Trust) on behalf of Wessex and West Midlands GLH for GMS Neurology specialist test group. All the green and amber, except for the genes with triplet repeats, were reviewed.

Created: 2 Sep 2019, 4:46 p.m. | Last Modified: 2 Sep 2019, 4:46 p.m.

Panel Version: 1.101

Review and rating submitted by Nick Beauchamp (Sheffield Diagnostic genetics Service), on behalf of Yorkshire and North East GLH for GMS Neurology specialist test group.

Created: 23 Jul 2019, 3:51 p.m. | Last Modified: 23 Jul 2019, 3:51 p.m.

Panel Version: 1.74

Review and rating submitted byJames Polke (North Bristol NHS Trust), unless specified in the review comment, on behalf of London North GLH for GMS Neurology specialist test group.

Created: 23 Apr 2019, 5:35 p.m.

Green List (high evidence)