King syndrome, also known as King-Denborough syndrome, is a congenital disease that consists of myopathy, malignant hyperthermia, dysmorphic facial features and musculoskeletal deformities. It may be linked to a genetic etiology.
Patients with King syndrome present in childhood, although the disease is seen from birth. The first cases reported were in males, who are more frequently affected than females. Currently, diagnostic criteria for the disease are vague. King syndrome (KS) was thought to be sporadic, but a genetic component has been suggested, with a possible autosomal dominant inheritance pattern . KS shares many features with Noonan syndrome, however, the relationship between the two diseases has yet to be established  . Despite similarities in clinical presentation, symptoms classically associated with Noonan syndrome, including coagulopathy, lymphatic swelling of the extremities, and wide spaced eyes, are not seen in patients with KS. It is unclear whether or not KS is a unique disorder, but it may be the common manifestation of several congenital myopathies  .
Relatives of the affected individuals have been found to have skeletal abnormalities or raised creatinine phosphokinase (CPK) levels . Many with KS are diagnosed with malignant hyperthermia as the first sign of KS, which then prompts further investigation, although the malignant hyperthermia is sometimes fatal.
KS is a progressive condition and is characterized by worsening myopathy which may first appear as developmental delay in the motor domain, kyphosis, scoliosis, winged scapula and weak tendon reflexes . There may be other skeletal deformities in the lumbar and thoracic spine as well as the chest wall, such as pectus carinatum. In addition, KS patients often have a short stature.
Other features associated with KS include low-set ears, webbed neck, crowding and misalignment of teeth, drooping eyelids, undescended testes, down-slanting palpebral fissures and an underdeveloped lower jaw . Cleft palate and high arched palate have been reported . KS has not been linked to intellectual disability.
Apart from the assessment of clinical features, there are no specific diagnostic tests for King syndrome. Despite the known characteristic features, it is still difficult to correctly identify KS. Patients in whom KS is suspected may be further investigated before exposure to anesthetic agents occurs. The available exams include: