The age at which child presents with KDSS may vary from new born to as late as 11 years of age. This disease is very rare as only less than 10% of children with hypothyroid myopathy develops this condition. Along with features of hypothyroidism the main additional feature is muscle hypertrophy. It can happen in any muscle of the limbs, but commonly affects the proximal muscles giving the typical Hercules appearance. Even though the muscle appears enlarged, it is weak and so the affliction is pseudo hypertrophy especially of the calf muscles. Other features are pseudomyotonia, myokymia, slow tendon reflex, slowed muscle contractions and relaxations, muscle stiffness, proximal muscle weakness and myopathy. The severity of these symptoms are determined by the period of hypothyroidism and the<unk> e of deficiency of thyroid hormones. EMG is either normal or may show myopathic low amplitude and short motor unit's potential (MUAPS). The enzymes creatine kinase is elevated usually.
Kocher–Debre–Semelaigne syndrome
Omenn syndrome
Wolcott–Rallison syndrome
Kapur–Toriello syndrome
Ellis–Van Creveld syndrome
Malouf syndrome
Young–Madders syndrome
Wilson–Turner syndrome