[MIM 618 524]

(MYOTREM, congenital myopathy 16)

Very rare. Sporadic or autosomal dominant transmission of a mutation of the MYPBPC1 gene (12q23.2) coding for the slow skeletal-type muscle isoform of myosin-binding protein C.

Other mutations of this gene cause various types of arthrogryposis (see this term).

This is a sarcomeric myopathy characterized by:

• neonatal hypotonia with lingual tremor, feeding difficulties
• delayed walking, unsteady gait, proximal muscle weakness
• progressive appearance of a high frequency tremor of the limbs
• absence of contractures (sometimes moderate ones in the elbows and ankles)
• muscle atrophy of varying importance
• normal intellectual development
• evolution that seems to stabilize in adolescence
• sometimes: winged scapulae, scoliosis, lordosis, spine stiffness, micrognathia, microstomy
• normal CPK level
• histology: predominance of atrophic type 1 fibers

Anesthetic implications:

no reported cases. Possible difficult laryngoscopy or intubation. Avoid succinylcholine and probably halogenated agents

References :

-        Stavusis J, Lace B, Schafer J, Geist J, Inashkina I et al.
Novel mutations in MYBPC1 are associated with myogenic tremor and mild myopathy. 
Ann Neurol 2019; 86: 129-42.

-        Shirashi K, Tsuburaya RS, Mukaida N, Yoshida T.
A case of congenital myopathy accompanied by tremor due to a MYBPC1 mutation.
Pediatrics International 2022; 64: e15061

-        Zhao Y,Yan C, Ji K.
Ultrasonography of muscle vibration caused by MYBPC1 variant.
JAMA Neurology 2023  in press

Updated: April 2023