A Newborn with Severe Ventriculomegaly: Expanding the PPP2R1A Gene Mutation Phenotype

Abstract

Protein phosphatase 2A (PP2A) is a heterotrimeric protein serine/threonine phosphatase that regulates a diverse range of cellular activities. The PPP2R1A gene on chromosome 19 (19q13.41) encodes the α isoform of the scaffolding subunit of the PP2A holoenzyme, which functions to link the catalytic subunit to the regulatory subunit. Here we present a case of a newborn boy with a novel PPP2R1A gene mutation (c.548G>A; p.Arg183Gln) with severe lateral and third ventriculomegaly, hypoplastic corpus callosum, and pontocerebellar hypoplasia. To our knowledge, this is the sixth case reported in the literature, thus expanding the phenotype of this rare genetic condition.

Keywords: PPP2R1A; protein phosphatase 2A; ventriculomegaly.

Fig. 1

( A ) Sagittal HASTE image shows severe ventriculomegaly, pontine hypoplasia ( asterisk ), and dysplastic vermis (arrow). ( B ) Axial HASTE (HAlf fourier Single-shot Turbo spin Echo) image demonstrates severe ventriculomegaly with very thin, abnormally smooth, and packed cortex suspicious for polymicrogyria. ( C ) Axial HASTE image redemonstrating severe ventriculomegaly, as well as abnormal rotation of the thalami and poor definition of the posterior limb of the internal capsules that may represent incomplete separation of the thalami from the putamina. ( D ) Axial HASTE image is notable for floating choroid plexuses “on stalks” both flipped into the left lateral ventricle, only scant commissurated callosal fibers noted anteriorly (arrow), and no callosal fibers posteriorly.