French researchers report a case of neonatal hypotonia that was found to be related to a pathological sequence variant in the TNNC2 gene encoding type C troponin:
- this gene was already known to cause early-onset myopathy;
- in a pair of siblings, the first died in the neonatal period and the second was the subject of a medical termination of pregnancy;
- in both patients, a homozygous variant was identified in a region controlling splicing of the TNNC2 gene;
- functional studies confirmed the absence of protein, validating a loss-of-function mechanism.
The originality of this observation lies in the unusual mode of transmission, as this is the first case ever described of autosomal recessive inheritance for the TNNC2 gene.
