Case 2: A Profoundly Hypotonic Premature Infant.

A female infant is born at 32 weeks’ gestation to a 30-year-old gravida 3, para 2 woman. The pregnancy had been complicated by dichorionic-diamniotic twin gestation and polyhydramnios, small stomach, and micrognathia of 1 twin. The pregnancy is the result of in vitro fertilization performed outside the United States, using the mother’s egg and father’s sperm. No preimplantation genetic testing was performed. The infant is delivered via cesarean section under general anesthesia for nonreassuring fetal monitoring. Her Apgar scores are 1, 1, 2, 3, and 3 at 1, 5, 10, 15, and 20 minutes, respectively. She requires endotracheal intubation, chest compressions, and exogenous surfactant administration in the delivery room. She maintains a stable heart rate (>100 beats/min) after resuscitation and has peripheral acrocyanosis but has no spontaneous respiratory effort, activity, or grimace. Physical examination reveals an appropriate-for-gestational age infant. She is significantly hypotonic and lethargic, with no spontaneous movements. Neurologic examination demonstrates open eyes, with nonreactive pupils and no tracking. Her tongue is midline and protruding, with no fasciculations. She has flaccid arms and outwardly deviated hips. She has no palmar or plantar grasp reflexes and minimal withdrawal from pain. She has reduced palm and sole creases. Contractures of knees, wrists, and elbows are noted. She has long digits and high plantar arches. Her abnormal neurologic examination is initially attributed to general anesthesia exposure and hypoxic-ischemic encephalopathy but does not improve with time. Spinal muscular atrophy sequencing is normal, showing 2 copies of …