Hereditary ataxia with onset in adulthood

Gene: SPTAN1

Green List (high evidence)

The rating of this gene has been updated to Green and the mode of inheritance set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted following NHS Genomic Medicine Service approval.

Created: 10 Oct 2023, 4:24 p.m. | Last Modified: 10 Oct 2023, 4:32 p.m.

Panel Version: 4.24

Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted

Green List (high evidence)

Comment on mode of inheritance: Although there are three unrelated cases reported with biallelic SPTAN1 variants and hereditary spastic paraplegia, they do not present with ataxia (PMID:31515523; PMID:34526651). Hence, the MOI should remain as "MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted".

Created: 17 Aug 2023, 8:56 a.m. | Last Modified: 17 Aug 2023, 8:56 a.m.

Panel Version: 4.19

Comment on classification: This gene should be rated Green as there are several unrelated cases (many more than three cases identified with different variants) from multiple ethnicities reported with adult-onset ataxia and was also supported by functional studies including results from mouse model.

Out of 22 patients from 14 families identified with SPTAN1 variants in PMID:35150594, four unrelated patients displaying p.Lys2083del variant were reported with cerebellar ataxia, of these two had early-onset, one had juvenile-onset and one had adult-onset.

In PMID:36331550, authors carried out SPTAN1 gene enrichment analysis in the rare disease component of the 100,000 Genomes Project and screened 100,000 Genomes Project, DECIPHER database, and GeneMatcher to identify individuals with SPTAN1 variants. Statistically significant enrichment of rare probably damaging SPTAN1 variants were identified in families with hereditary ataxia (HA) or spastic paraplegia (HSP). Out of 31 individuals identified with SPTAN1 variants, five (from three families) were presented with complex HA/HSP and two were presented with pure HA. The two patients presented with pure ataxia had adult-onset.

A 33-year old Korean woman identified with SPTAN1 variant (p.Lys2083del) was reported with cerebellar ataxia in PMID:36408834, being the first reported case of SPTAN1-related cerebellar ataxia.

In addition, a strain of C57BL/6J mice harbouring a single point mutation in Sptan1 (c.3293G > A/ p.Arg1098Gln) with reduced CaM affinity and intrinsically enhanced sensitivity to calpain proteolysis was reported in PMID:33790315. Homozygotes are embryonically lethal and heterozygotes develop a progressive ataxia.
Sources: Literature

Created: 6 Feb 2023, 4:02 p.m.

Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted

Phenotypes
Developmental and epileptic encephalopathy 5, OMIM:613477; Cerebellar ataxia, MONDO:0000437; Hereditary spastic paraplegia, MONDO:0019064

Publications

• 33790315
• 35150594
• 36331550
• 36408834