A TPM2 mutation causes congenital myopathy with fibre-type disproportion.

We report a 9-year-old girl with delayed motor milestones and respiratory difficulty since birth. She presented as a floppy infant, with generalised muscle wasting, dysphagia and facial weakness. The muscle biopsy of the biceps brachii revealed congenital fibre-type disproportion (CFTD) and Sanger sequencing detected a pathogenic variant in the beta-tropomyosin (TPM2) gene (c.415_417delGAG; p.Glu139del). There has been only one previous report of CFTD associated with p.Glu139del in the TPM2 gene.