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Proximal variants in CCND2 associated with microcephaly, short stature, and developmental delay: A case series and review of inverse brain growth phenotypes
Author(s) -
Pirozzi Filomena,
Lee Benson,
Horsley Nicole,
Burkardt Deepika D.,
Dobyns William B.,
Graham John M.,
Dentici Maria L.,
Cesario Claudia,
Schallner Jens,
Porrmann Joseph,
Di Donato Nataliya,
SanchezLara Pedro A.,
Mirzaa Ghayda M.
Publication year - 2021
Publication title -
american journal of medical genetics part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.064
H-Index - 112
eISSN - 1552-4833
pISSN - 1552-4825
DOI - 10.1002/ajmg.a.62362
Subject(s) - megalencephaly , microcephaly , cyclin d2 , polymicrogyria , biology , genetics , phenotype , intellectual disability , neuroscience , gene , cell cycle , cyclin , epilepsy
Cyclin D2 (CCND2) is a critical cell cycle regulator and key member of the cyclin D2‐CDK4 (DC) complex. De novo variants of CCND2 clustering in the distal part of the protein have been identified as pathogenic causes of brain overgrowth (megalencephaly, MEG) and severe cortical malformations in children including the megalencephaly‐polymicrogyria‐polydactyly‐hydrocephalus (MPPH) syndrome. Megalencephaly‐associated CCND2 variants are localized to the terminal exon and result in accumulation of degradation‐resistant protein. We identified five individuals from three unrelated families with novel variants in the proximal region of CCND2 associated with microcephaly, mildly simplified cortical gyral pattern, symmetric short stature, and mild developmental delay. Identified variants include de novo frameshift variants and a dominantly inherited stop‐gain variant segregating with the phenotype. This is the first reported association between proximal CCND2 variants and microcephaly, to our knowledge. This series expands the phenotypic spectrum of CCND2 ‐related disorders and suggests that distinct classes of CCND2 variants are associated with reciprocal effects on human brain growth (microcephaly and megalencephaly due to possible loss or gain of protein function, respectively), adding to the growing paradigm of inverse phenotypes due to dysregulation of key brain growth genes.