The recurrent TUBB3 Gly98Ser substitution is the first described to inconsistently result in CFEOM3

Scott C. Smith, Ann Haskins Olney, Angela Beavers, Joanna Spaulding, Marilu Nelson, Shelly Nielsen, Jennifer N. Sanmann

Research output: Contribution to journalArticle

Abstract

Missense variants in TUBB3 have historically been associated with either congenital fibrosis of the extraocular muscles type 3 (CFEOM3) or malformations of cortical development (MCD). Until a recent report identified two amino acid substitutions in four patients that had clinical features of both disorders, pathogenic variants of TUBB3 were thought distinct to either respective disorder. Three recurrent de novo Gly71Arg TUBB3 substitutions and a single patient with a de novo Gly98Ser substitution blurred the MCD and CFEOM3 phenotypic distinctions. Here we report a second patient with a missense c.292G>A (p.Gly98Ser) substitution, but without CFEOM3, the first reported evidence that even the same TUBB3 substitution can produce a spectrum of TUBB3 syndrome phenotypes. Our patient presented with amblyopia, exotropia, optic disc pallor, and developmental delay. Neuroimaging identified hypoplasia of the corpus callosum, interdigitation of the frontal lobe gyri, and dysplasia or hypoplasia of the optic nerves, basal ganglia, brainstem, and cerebellum. This report identifies the TUBB3 Gly98Ser substitution to be recurrent but inconsistently including CFEOM3, and identifies the absence of joint contractures and the presence of optic disc abnormalities that may be genotype-specific to the TUBB3 Gly98Ser substitution.

Original languageEnglish (US)
Pages (from-to)2161-2167
Number of pages7
JournalAmerican Journal of Medical Genetics, Part A
Volume182
Issue number9
DOIs
StatePublished - Sep 1 2020

Keywords

  • TUBB3 Gly98Ser
  • congenital fibrosis of the extraocular muscles
  • genotype–phenotype comparison
  • malformations of cortical development

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

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