Ataxia and cerebellar anomalies - narrow panel

Gene: MAB21L1

Green List (high evidence)

Comment on list classification: There are nine patients from six unrelated families reported with cerebellar anomalies and with biallelic MAB21L1 variants. Hence, this gene can be promoted to green rating in the next GMS update.

Created: 19 May 2026, 1:51 p.m. | Last Modified: 19 May 2026, 1:51 p.m.

Panel Version: 9.3

PMID:27103078 (2017) reported the identification of a homozygous frameshift variant in MAB21L1 gene (p.Cys246Leufs*18) in an 8-year-old Algerian boy with scrotum agensis, ophthalmological anomalies, cerebellar malformation, facial dysmorphism and global developmental delay. Ocular anomalies included nystagmus, convergent strabismus and corneal dystrophy. There is also functional evidence available from knockout mice which presented a similar malformative association of ophthalmological malformations of the anterior chamber and preputial glands hypoplasia.

PMID:30487245 (2019) reported the identification of four homozygous MAB21L1 loss of function variants (p.Glu281fs*20, p.Arg287Glufs*14 p.Tyr280* and p.Ser93Serfs*48) and one missense variant (p.Gln233Pro) in 10 affected individuals from five consanguineous families with a distinctive autosomal recessive neurodevelopmental syndrome. Cerebellar anomalies such as cerebellar hypoplasia/ Dandy-Walker malformation/ Cerebellovermian hypoplasia with/ without pontine involvement was reported in eight patients from five families.

Biallelic variants in this gene are associated with relevant phenotypes in OMIM (MIM #618479, last accessed 19 May 2026), Gene2Phenotype (with 'definitive' rating on the DD and Eye panels) and ClinGen (Strong rating by Syndromic disorders Expert panel - https://search.clinicalgenome.org/CCID:008388)
Sources: Literature

Created: 19 May 2026, 1:50 p.m.

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Cerebellar, ocular, craniofacial, and genital syndrome, OMIM:618479; cerebellar, ocular, craniofacial, and genital syndrome, MONDO:0032774

Publications

• 27103078
• 30487245