Expanding the Spectrum of Congenital Myopathy Linked to Variants in the MYBPC1 Gene: A Clinical Report.

OBJECTIVES: Heterozygous missense variants in MYBPC1 have been recently identified in 13 patients from 6 families with congenital myopathy with tremor. All the patients had mild skeletal myopathy invariably associated with a distinctive myogenic tremor and hypotonia with gradual clinical improvement. However, no phenotypic description has been reported for the neonatal respiratory impairment that patients may suffer.

METHODS: We report 3 new patients from 2 independent families with congenital myopathy with tremor.

RESULTS: Tremors and respiratory distress associated with stridor should raise the diagnosis of congenital myopathy with tremors linked to MYBPC1 -dominant variants in children with neonatal hypotonia.

DISCUSSION: Neonatal severe respiratory impairment requiring intensive noninvasive ventilation because of stridor is described in 2 patients. Stridor was previously reported in one other case and is part of the clinical features.