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Mental retardation associated with myopathy, facial malformation, and seizures.

Puerto Rican Infant Hypotonia Syndrome.

Three cases have been described; genetic inheritance unknown.

Features include myopathy, (congenital fiber type disproportion, i.e., type I muscle fibers are significantly smaller than type II fibers (normally about the same size), and a predominance of type I fibers by numbers (normally about equal)), nonprogressive hypotonia, facial malformations (hypertelorism, broad nasal root, long philtrum, mouth held open, high-arched and narrow palate, microdontia), delayed bone age with abnormal ossification, pectus excavatum, seizures, and mental retardation.

Direct laryngoscopy and tracheal intubation could be difficult because of facial malformations. Avoid anesthetic muscle relaxants until the airway has been secured. Evaluate neurological function (clinical, history, CT/MRI, EEG). Consider interaction between antiepileptic treatment and anesthetic drugs. Evaluate myopathy (history, clinical, creatine phosphokinase); avoid succinylcholine and halogenated drugs. Reduce neuromuscular blocking agent doses because of hypotonia and use a peripheral nerve stimulator.

Qazi QH, Markouizos D, Rao C, et al: A syndrome of hypotonia, psychomotor retardation, seizures, delayed and dysharmonic skeletal maturation, and congenital fibre type disproportion. J Med Genet 31(5):405, 1994.

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