Kyphoscoliosis and easy fatigability in a 14-year-old boy

Thepatientwasa14-year-oldThaiboywhopresentedatanorthopedic clinic with kyphoscoliosis first detected 1 yearprior to medical attention. He was the first child of non-consanguineous parents; the pregnancy and delivery wereuneventful.He had normal developmental milestones.Thepatient noticed easy fatigability after exercise which wors-ened during the past year. His younger brother was 10years old and healthy. There was no history ofneuromuscular disease in his family. His father passedaway due to an unrelated incident. General examinationrevealed a body weight of 30 kg and a height of 149 cm,bilateral ptosis, high-arched palate, kyphoscoliosis, andasymmetrical chest wall. Proximal muscle weakness ofgrade 4 by Medical Research Council Scale in all extrem-itiesandareflexiawerenoted.Themuscletonewasnormal.SerumCKwas49 IU/L.Echocardiogramshowedmildpul-monary and tricuspid regurgitation. Pulmonary functiontestsshowedrestrictivelungdisease;theforcedvitalcapac-ity was 1.56 L (51% of predicted). Sleep study revealedapnea-hypopnea index 13.6 per hour associated withsevere oxygen desaturation (minimum SpO