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Review
. 2021 Aug;185(8):2445-2454.
doi: 10.1002/ajmg.a.62350. Epub 2021 May 25.

Delineating the Smith-Kingsmore syndrome phenotype: Investigation of 16 patients with the MTOR c.5395G > A p.(Glu1799Lys) missense variant

Rebecca L Poole  1   2 , Philippa D K Curry  3 , Ruta Marcinkute  4 , Carole Brewer  5 , David Coman  6 , Emma Hobson  7 , Diana Johnson  8 , Sally Ann Lynch  9 , Anand Saggar  10 , Claire Searle  11 , Ingrid Scurr  12 , Peter D Turnpenny  5 , Pradeep Vasudevan  13 , Katrina Tatton-Brown  3   10
Affiliations
Review

Delineating the Smith-Kingsmore syndrome phenotype: Investigation of 16 patients with the MTOR c.5395G > A p.(Glu1799Lys) missense variant

Rebecca L Poole et al. Am J Med Genet A. 2021 Aug.

Abstract

Smith-Kingsmore Syndrome (SKS) is a rare genetic syndrome associated with megalencephaly, a variable intellectual disability, autism spectrum disorder, and MTOR gain of function variants. Only 30 patients with MTOR missense variants are published, including 14 (47%) with the MTOR c.5395G>A p.(Glu1799Lys) variant. Limited phenotypic data impacts the quality of information delivered to families and the robustness of interpretation of novel MTOR missense variation. This study aims to improve our understanding of the SKS phenotype through the investigation of 16 further patients with the MTOR c.5395G>A p.(Glu1799Lys) variant. Through the careful phenotypic evaluation of these 16 patients and integration with data from 14 previously reported patients, we have defined major (100% patients) and frequent (>15%) SKS clinical characteristics and, using these data, proposed guidance for evidence-based management. In addition, in the absence of functional studies, we suggest that the combination of the SKS major clinical features of megalencephaly (where the head circumference is at least 3SD) and an intellectual disability with a de novo MTOR missense variant (absent from population databases) should be considered diagnostic for SKS.

Keywords: MTOR; Smith-Kingsmore syndrome; megalencephaly.

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References

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