Cerebellar and Pontocerebellar Hypoplasia

Gene: CHP1

Green List (high evidence)

2 different consanguineous families with 2 affected siblings with ataxia (1 paediatric onset, 1 adult onset). 3 of the patients had cerebellar atrophy. WES identified homozygous variants in CHP1 gene in both families (K19del and Arg91Cys), which segregated with the disorder in the family.

Decreased CHP1 protein on IHC of cerebellar tissue in family with Arg91Cys variant. In vitro functional expression studies in HEK293 cells showed that the K19del mutation resulted in decreased protein expression, with normal levels of transcript, suggesting defects in protein stability. The mutant protein formed massive protein aggregates in transfected neuronal cell bodies and neurite-like projections, whereas the wildtype protein showed a more uniform distribution. The mutant protein altered CHP1 association into functional complexes and impaired membrane localization of the Na+/H+ transporter NHE1. The findings indicated that the CHP1 mutation likely causes ataxia in an NHE1-dependent manner, resembling the mechanism observed in the Chp1 vacillator mutant mouse.
Sources: Literature

Created: 26 Jan 2022, 10:12 p.m.

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Spastic ataxia 9, autosomal recessive, OMIM #618438

Publications

• PMID: 29379881, 32787936