A 10-month-old girl with genetically confirmed spinal muscular atrophy (SMA) (homozygous deletion of SMN1 exon 7) was identified through newborn screening. By 9 months, she could sit with support and had preserved hand function. She had received five doses of nusinersen before consideration of onasemnogene abeparvovec (OA), an adeno-associated virus-based gene replacement therapy.

She presented with painful, necrotic ulcerations affecting the nasal tip, fingertips and right foot (figure 1A). There were no preceding infectious …