Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-Like Episodes (MELAS) is a rare progressive disorder that affects multiple systems in the body. Problems with the nervous system and muscles, lactic acid build-up and stroke-like episodes are identifiers of the condition. 

MELAS normally manifests between the ages of two and 15 years of age, with 75% of cases diagnosed before the age of 20. Seizures, recurrent headaches, loss of appetite, and vomiting are the most commonly reported symptoms, correlating with the side effects of lactic acidosis.

What causes MELAS?

A mutation in mitochondrial DNA causes MELAS to occur. The genetic disorder is passed on from mother to child, while MELAS–affected males are unable to pass on the mutation.

GlobalData epidemiologists conducted a thorough review of the literature to determine epidemiology trends of MELAS. Their findings show diagnosed prevalence is highest in the Western markets, though it is very rare globally. 

Diagnosed rates of MELAS

GlobalData epidemiologists forecast a 10–year model of MELAS diagnosed prevalence and prevalent cases in the 16 major markets (16MM: US, France, Germany, Italy, Spain, UK, Japan, Australia, Brazil, Canada, China, India, Mexico, Russia, South Africa, and South Korea) from 2018–2028. Western markets have the highest diagnosed prevalence rates, with a rate of 0.00095% seen in the US, UK, Spain, Italy, Germany, France, Australia, and Canada.

Brazil, India, Mexico, Russia, and South Africa have a slightly lower diagnosed prevalence rate of 0.00057%. The Asian markets of China, South Korea, and Japan has the lowest figure, with a rate of 0.00018%.

Figure 1 shows the diagnosed prevalence rates as explained above.

Figure 1: Diagnosed Prevalence of MELAS in the 16MM in 2019

As MELAS is a rare disease, more data is needed to accurately predict future trends worldwide. There is no significant evidence to suggest MELAS is associated with ethnicity, and as such the cause for higher rates being seen in the Western markets may be due to more awareness of the disease resulting in more frequent and accurate testing.