Leigh syndrome (also called Leigh disease and subacute necrotizing encephalomyelopathy) is an inherited neurometabolic disorder that affects the central nervous system. It is named after  Archibald Denis Leigh, a British neuropsychiatrist who first described the condition in 1951. Normal levels of thiamine, thiamine monophosphate, and thiamine diphosphate are commonly found but there is a reduced or absent level of thiamine triphosphate. This is thought to be caused by a blockage in the enzyme thiamine-diphosphate kinase, and therefore treatment in some patients would be to take thiamine triphosphate daily. Signs and symptoms
The symptoms of Leigh syndrome are classically described as beginning in infancy and leading to death within a span of several years; however, as more cases are recognized, it is apparent that symptoms can emerge at any age—including adolescence or adulthood—and patients can survive for many years following diagnosis. Symptoms are often first seen after a triggering event that taxes the bodys energy production, such as an infection or surgery. The general course of Leigh syndrome is one of episodic developmental regression during times of metabolic stress. Some patients have long periods without disease progression while others develop progressive decline.Infants with the syndrome have symptoms that include diarrhea, vomiting, and dysphagia (trouble swallowing or sucking), leading to a failure to thrive. Children with early Leigh disease also may appear irritable and cry much more than healthy babies. Seizures are often seen.
When hyperbilirubinemia is not treated with phototherapy, the bilirubin can accumulate in the basal ganglia and cause lesions similar to those seen in Leigh syndrome. This is not common since the advent of phototherapy. Treatment
Succinic acid has been studied, and shown effective for both Leigh syndrome, and MELAS syndrome. A high-fat, low-carbohydrate diet may be followed if a gene on the X chromosome is implicated in an individuals Leigh syndrome. Thiamine (vitamin B1) may be given if pyruvate dehydrogenase deficiency is known or suspected. The symptoms of lactic acidosis are treated by supplementing the diet with sodium bicarbonate (baking soda) or sodium citrate, but these substances do not treat the cause of Leigh syndrome. Dichloroacetate may also be effective in treating Leigh syndrome-associated lactic acidosis; research is ongoing on this substance. Coenzyme Q10 supplements have been seen to improve symptoms in some cases.Clinical trials of the drug EPI-743 for Leigh syndrome are ongoing.In 2016, John Zhang and his team at New Hope Fertility Center in New York, USA, performed a spindle transfer mitochondrial donation technique on a mother in Mexico who was at risk of producing a baby with Leigh disease. A healthy boy was born on 6 April 2016. However, it is not yet certain if the technique is completely reliable and safe. Prognosis
Different genetic causes and types of Leigh syndrome have different prognoses, though all are poor. The most severe forms of the disease, caused by a full deficiency in one of the affected proteins, cause death at a few years of age.