Ataxia - paediatric

Gene: PIK3R5

Red List (low evidence)

Al Tassan et al. (2012) reported 4 sibs, from consanguineous Saudi Arabian family, with ataxia-oculomotor apraxia. The proband developed progressive unsteady gait and had frequent falls at age 14 years with later onset of arm dysmetria and dysarthria. He became wheelchair-bound at age 23. Ocular movement was impaired, with slowed saccadic eye movements and head-eye lag resulting in head thrust, but smooth pursuit was normal. He had severe limb and axial dysmetria with mild distal atrophy and weakness affecting the lower limbs more than the upper limbs. He also had distal sensory impairment, more prominent in the lower limbs, areflexia, and axonal sensory polyneuropathy with absent sensory nerve action potentials in the lower limbs. Laboratory studies showed increased level of alpha-fetoprotein, and brain MRI showed atrophy of the cerebellar folia and vermis. His 3 sibs were similarly affected. A homozygous mutation in the PIK3R5 gene (P629S) was found by linkage analysis followed by sequencing of the genes within the region.

Created: 27 Jan 2022, 3:28 a.m. | Last Modified: 27 Jan 2022, 3:28 a.m.

Panel Version: 0.10796

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Ataxia-oculomotor apraxia 3, OMIM #615217

Publications

• 22065524

Red List (low evidence)

Al Tassan et al. (2012) reported 4 sibs, from consanguineous Saudi Arabian family, with ataxia-oculomotor apraxia. The proband developed progressive unsteady gait and had frequent falls at age 14 years with later onset of arm dysmetria and dysarthria. He became wheelchair-bound at age 23. Ocular movement was impaired, with slowed saccadic eye movements and head-eye lag resulting in head thrust, but smooth pursuit was normal. He had severe limb and axial dysmetria with mild distal atrophy and weakness affecting the lower limbs more than the upper limbs. He also had distal sensory impairment, more prominent in the lower limbs, areflexia, and axonal sensory polyneuropathy with absent sensory nerve action potentials in the lower limbs. Laboratory studies showed increased level of alpha-fetoprotein, and brain MRI showed atrophy of the cerebellar folia and vermis. His 3 sibs were similarly affected. A homozygous mutation in the PIK3R5 gene (P629S) was found by linkage analysis followed by sequencing of the genes within the region.
Sources: Literature

Created: 27 Jan 2022, 12:09 a.m.

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Ataxia-oculomotor apraxia 3, OMIM #615217

Publications

• PubMed: 22065524