A Case of Mitochondrial Myopathy, Lactic Acidosis and Sideroblastic Anemia (MLASA Syndrome) and Long QT Interval in a 10-Year-Old Saudi Child.

MLASA syndrome is a rare mitochondrial disorder that presents in three distinct genetic forms: MLASA1, MLASA2, and MLASA3; MLASA1 is the most common form. The clinical features include mitochondrial myopathy, lactic acidosis, and sideroblastic anemia. Although presence of other features is not uncommon, its association with long QT (LQT) syndrome has not been described before. In addition, while MLASA syndrome has been reported from several countries worldwide, we present the first patient with MLASA1 syndrome from the Kingdom of Saudi Arabia in this case report. The 10-year-old girl with history of poor health since infancy and recurrent hospital admissions for infections and blood transfusions was referred to our hospital for allogeneic bone marrow transplantation. Early in her childhood, she was diagnosed with symptomatic LQT syndrome and, at a later age, with sideroblastic anemia. Whole-exome sequencing (WES) revealed homozygous mutations in the PUS1 gene and heterozygous mutations in the KCNQ1 gene. The WES test of the parents was negative, and there was no family history suggestive of a similar diagnosis. Therefore, our patient has most probably developed the syndrome as a result of a sporadic de novo mutation; however, the possibility of sex cell germline mosaicism cannot be excluded. Heterozygous KCNQ1 gene mutation is associated with the development of type 1 LQT syndrome. Detection of the MLASA syndrome and proper intervention at an early age are crucial for successful management. Associated LQT syndrome should always be anticipated. Despite the presence of a fully tissue-matched sibling, the parents of our patient declined the option of allogeneic bone marrow transplantation due to potential severe cardiac and liver complications.