Prevalence < 1/106. Autosomal recessive transmission of a mutation of the MYMK gene (9.q34.2).
- hypotonia, of peripheral (slowly progressive congenital myopathy with anomalies of type I fibers and moderately elevated CPK levels; early and severe scoliosis) or central origin (brain anomaly: ventriculomegaly, white matter anomalies, neuronal heterotopia, small spots of necrosiswith microcalcifications, small size brainstem and annular protuberance with enlarged prepontine and pontocerebellar cisterns).
- Moebius sequence: congenital bilateral facial palsy with impairment of ocular abduction
- Pierre Robin sequence: micrognathia, glossoptosis and cleft palate
- characteristic face: elongated and thin neck, elongated and poorly expressive face, epicanthus, long philtrum, upturned nose
- and growth delay.
Sometimes: absence of major pectoralis muscle with ulnar deviation of the hand (Poland sequence), laryngeal stenosis, unexplained intermittent hypertension crises with sweating and facial flushing, hydronephrosis, or clubfeet.
Intelligence may be normal but intellectual deficit has been reported.
risk of difficult mask ventilation and intubation; if CPK level is high: avoidance of halogenated agents ? Choose a smaller than expected (laryngeal stenosis?) endotracheal tube. Risk of restrictive respiratory syndrome and pulmonary hypertension (scoliosis)
Updated: November 2017