Ataxia and cerebellar anomalies - narrow panel

Gene: SKOR2

Green List (high evidence)

Comment on list classification: There are more than 3 unrelated individuals reported with biallelic SKOR2 variants and childhood onset ataxia and /or evidence of cerebellar anomalies on MRI. Hence, this gene should be promoted to Green at the next update.

Created: 21 Apr 2026, 5:05 p.m. | Last Modified: 21 Apr 2026, 5:07 p.m.

Panel Version: 8.81

PMID: 29997391 Valence et al., 2019
Patient P15 - 10yo female, consanguineous Turkish parents; she presented with neonatal hypotonia and psychomotor delay; at age 10, she had scoliosis, nystagmus, mild ID, and a nonprogressive ataxia with ataxic gait. She was homozygous for SKOR2 variant NM_001278063.1: c.2750C>G; p.Ser917*. Cerebellar dysplasia seen on brain MRI.

PMID: 40890458 Farazi Fard et al., 2025
9 patients from 2 unrelated consanguineous Iranian families:
Family 1 - 8 affected individuals homozygous for SKOR2 c.374G>C, p.Arg125Pro variant; ataxia present in 6/8 individuals, cerebellar hypoplasia in 8/8. Other phenotypes: scoliosis (5/8), strabismus (4/8), and other more variable features.
Family 2 - affected 6yo female proband homozygous for SKOR2 c.1271_1274del, p.Lys424Argfs*71 variant; she had strabismus, hypotonia, cerebellar hypoplasia, and osteomalacia, but no ataxia reported.

PMID: 41821366 Abu-El-Haija et al., 2026 - Online ahead of print
Report of eight individuals from five unrelated families (from Iraq, Turkey, Pakistan, Morocco, and South East Asia) with biallelic variants in SKOR2 associated with a phenotypic spectrum of cerebellar hypoplasia, microcephaly, ataxia, developmental delays and intellectual disability. Disease with childhood-onset, consanguinity reported in 7/8 individuals. Ataxic gait noted in 4 individuals, generally delayed walking age (>2 years in 6 cases).
Intellectual disability was present in 5/5 individuals assessed (4 mild, IQ = 55-58, and 1 case with severe ID). Cerebellar anomalies noted on brain MRI in 6/6 patients, including cerebellar hypoplasia /atrophy in 4 cases. Scoliosis / kyphosis noted in 3 patients.
Sources: Literature

Created: 21 Apr 2026, 5:03 p.m.

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Valence-Farazi cerebellar ataxia syndrome, OMIM: 621386; Valence-Farazi cerebellar ataxia syndrome, MONDO:0980707

Publications

• 29997391
• 40890458
• 41821366