A patient with typical clinical features of mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) but without an obvious genetic cause: a case report.
BACKGROUND
There are currently 23 missense point mutations and one 4 basepair deletion spanning different mitochondrial genes associated with mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS). The spectrum of mitochondrial DNA mutations in Arab patients with MELAS is largely unknown.


METHODS
A standard clinical examination was carried out on a 34-year-old Saudi woman showing clinical features of MELAS. Fresh frozen muscle tissue was subjected to enzyme histochemical analysis. DNA was extracted from her leukocytes and muscle tissue, and the full mitochondrial genome was screened for base substitution mutations and deletions. Additionally, we screened the polymerase gamma-1 nuclear gene for mutations. The patient was negative for the most common m.3243 A>G MELAS mutation. Sequencing the full mitochondrial genome did not reveal any known or potentially pathogenic sequence changes. The polymerase gamma-1 gene was also free from mutations.


CONCLUSIONS
The clinical picture described here typically fits that observed in patients with MELAS or mitochondrial stroke-like events, but mutations in recognized genes (mitochondrial DNA and polymerase gamma-1 gene) were absent. We report the case of a patient with typical clinical features of MELAS, but without an obvious genetic cause.
Abu-Amero
Khaled K
KK
Molecular Genetics Laboratory, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
Al-Dhalaan
Hesham
H
Bohlega
Saeed
S
Hellani
Ali
A
Taylor
Robert W
RW