case_images: PMC7241273_01
case_images: (
  A) Genogram of Family. Red arrow indicates index case. (
  B) Calf hypertrophy in a male (case A:16) and female (case A:30). (
  C) EMG showing myotonic activity exacerbated by needle movement from case A:30.
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case_images: PMC7241273_01_wellcomeopenres-5-17445-g0000.jpg
case_images: f1
case_images: This large family from Chile includes 16 affected members of five generations who carry the SCN4A G1306E mutation ( Figure 1A). Examination demonstrated a robust physical build, more marked in the females than in the males ( Figure 1B). Electromyography showed permanent myotonic discharges ( Figure 1C) in all cases.
case_images: PMC7241273_02
case_images: PMC7241273_03
case_images: PMC7241273_04
case_images: Case C as an infant demonstrating nasogastric tube required for feeding.
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case_images: PMC7241273_04_wellcomeopenres-5-17445-g0001.jpg
case_images: f2
case_images: His parents noted he had always had difficulty opening his eyes and choking on feeds with an unsafe swallow that required NG tube insertion ( Figure 2) and subsequently PEG tube insertion.
case_images: Frequency of G1306E cases experiencing stridor/laryngospasm and the requirement for hospitalisation.
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case_images: PMC7241273_04_wellcomeopenres-5-17445-g0002.jpg
case_images: f3
case_images: The literature review mirrored the frequency of stridor/laryngospasm and respiratory events seen in our newly described patients (100%) with 25/30 (83%) reported G1306E cases experiencing these symptoms ( Figure 3).