[Steinert's myotonic dystrophy: severe neonatal form with unknown family history]

A child with severe generalized hypotonia and respiratory insufficiency, with an unknown positive family history for Steinert's disease, is referred. We want to point out the importance of correct anamnesis and of physical examination during pregnancy to suspect and diagnose rare and incurable fetal pathologies.

The child was born after caesarean section. Polyhydramnios and decreased fetal movements were noticed during pregnancy. At birth, the baby presented asphyxia (Apgar 4/6) and respiratory insufficiency: he was then intubed. He received assisted ventilation for 37 days. At the physical examination, the child appeared hypotonic, hyporeflexic, without sucking reflex, with arthrogryposis and ligament laxity. On first day, chest X-ray showed paralysis of the right hemidiaphragm. His mother presented with hypotonia of the facial muscles, lid drop, light muscular weakness, positivity to neostigmine test: we then assumed that the baby was affected by transient neonatal myasthenia gravis and neostigmine was carried on. Anyway, the general conditions of the baby didn't improve. We were able to establish diagnosis of Steinert's disease (a form of muscular dystrophy with autosomal dominant inheritance with incomplete penetrance) after some other examinations (negativity of acetylcholine receptor antibodies, elevation of creatine kinase level, myopathic pattern on electromyography). Gene DMPK alteration was documented with a molecular genetic test.