In a study of fifteen female and nine male patients with alternating hemiplegia, a mutation in ATP1A3 gene was present. Three patients showed heterozygous de-novo missense mutation. Six patients were found with de-novo missense mutation and one patient was identified with de-novo splice site mutation. De novo mutation is a mutation that occurs in the germ cell of one parent. Neither parent has the mutation, but it is passed to the child through the sperm or egg. Diagnosis
There is no diagnostic test for alternating hemiplegia, which makes it very difficult to diagnose. Also, because alternating hemiplegia is extremely rare, it is frequently missed and the patient is often misdiagnosed. Proper diagnosis, however, is critical for early treatment of the disorder. There are many criteria that can help in the proper general diagnosis of alternating hemiplegia. Criteria for diagnosis
First, the symptoms must be observed before the patient is 18 months of age. Second, there must be frequent episodes of hemiplegia, involving either side of the body. Third, other paroxysmal disorders including tonic attacks, dystonia, nystagmus, strabismus, dyspnoea, and other uncontrollable disorders are noticed to occur. Although common, the paroxysmal disorders involving the eye, nystagmus and strabismus, may not be apparent in older children and may not have been remembered in childhood so a lack of these symptoms does not rule out alternating hemiplegia. Fourth, all symptoms clear up directly after falling asleep and usually come back after waking during an attack.
Two types of blood tests are used to confirm the presence of a hormone deficiency: basal levels, where blood samples are taken–usually in the morning–without any form of stimulation, and dynamic tests, where blood tests are taken after the injection of a stimulating substance. Measurement of ACTH and growth hormone usually requires dynamic testing, whereas the other hormones (LH/FSH, prolactin, TSH) can typically be tested with basal levels. There is no adequate direct test for ADH levels, but ADH deficiency can be confirmed indirectly; oxytocin levels are not routinely measured.Generally, the finding of a combination of a low pituitary hormone together with a low hormone from the effector gland is indicative of hypopituitarism. Occasionally, the pituitary hormone may be normal but the effector gland hormone decreased; in this case, the pituitary is not responding appropriately to effector hormone changes, and the combination of findings is still suggestive of hypopituitarism. Basal tests
Levels of LH/FSH may be suppressed by a raised prolactin level, and are therefore not interpretable unless prolactin is low or normal. In men, the combination of low LH and FSH in combination with a low testosterone confirms LH/FSH deficiency; a high testosterone would indicate a  source elsewhere in the body (such as a testosterone-secreting tumor). In women, the diagnosis of LH/FSH deficiency depends on whether the woman has been through the menopause.