De novo variants in CNOT3 cause a variable neurodevelopmental disorder

Area of Science:

• Genetics
• Developmental Biology
• Neuroscience

Background:

• Exome sequencing has identified de novo variants in CNOT3 as a novel cause of developmental disorders.
• The DDD study and other large-scale sequencing efforts have contributed to the identification of affected individuals.

Purpose of the Study:

• To describe the molecular and clinical details of 16 probands with developmental disorders and de novo CNOT3 variants.
• To characterize the developmental phenotype associated with CNOT3 variants.
• To investigate the underlying mechanism of CNOT3-related disorders.

Main Methods:

• Exome-based sequencing.
• Clinical phenotyping of affected individuals.
• Molecular analysis of CNOT3 variants (protein-truncating and missense).

Main Results:

• Sixteen probands with de novo CNOT3 variants were identified and characterized.
• Consistent phenotypic features include hypotonia, small stature, developmental delay, behavioral problems, and intellectual disability.
• While no distinct facial phenotype was observed, some common dysmorphic features were noted. Eight cases had protein-truncating variants, suggesting haploinsufficiency as a likely mechanism.

Conclusions:

• De novo CNOT3 variants represent a newly recognized genetic cause of developmental disorders.
• The phenotype is characterized by global developmental delay, hypotonia, and intellectual disability, with variable dysmorphic features.
• Haploinsufficiency due to protein-truncating variants is the probable mechanism, with specific missense variants potentially impacting functional domains.