PIK3R2

Chr 19AD

phosphoinositide-3-kinase regulatory subunit 2

Also known as: MPPH, MPPH1, P85B, p85, p85-BETA, p85beta

NCBI Gene: 5296 ENSG00000105647 UniProt: O00459 OMIM: 603157

The protein encoded by PIK3R2 serves as a regulatory subunit of phosphatidylinositol 3-kinase (PI3K), a lipid kinase that phosphorylates phosphatidylinositol to generate second messengers in growth signaling pathways. Gain-of-function mutations cause megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome 1, inherited in an autosomal dominant pattern.

GeneReviews OMIM ResearchSummary from RefSeq, OMIM, Mechanism

Phosphatidylinositol 3-kinase (PI3K) is a lipid kinase that phosphorylates phosphatidylinositol and similar compounds, creating second messengers important in growth signaling pathways. PI3K functions as a heterodimer of a regulatory and a catalytic subunit. The protein encoded by this gene is a regulatory component of PI3K. Three transcript variants, one protein coding and the other two non-protein coding, have been found for this gene. [provided by RefSeq, Apr 2019]

GeneReviews OMIM ResearchGenerating clinical summary…

Primary Disease Associations & Inheritance

Megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome 1MIM #603387

Clinical highlights

Gene-disease validity (ClinGen)

overgrowth syndrome and/or cerebral malformations due to abnormalities in MTOR pathway genes · ADDefinitivesufficient evidence for diagnostic panels

Interpreting a novel variant

Gain of function is the curated mechanism (Gene2Phenotype), so a variant that simply removes the protein may not be the pathogenic class here — missense variants in functional domains often carry more weight.Curated gene-level mechanism — a prior for triage, not a per-variant call.

Active trials

Pubs (1 yr)

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P/LP submissions

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P/LP missense

0.49

LOEUF

GOF

Mechanism· G2P

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GeneReview available — PIK3R2