How to Cite this Article: Jain-Ghai S, Cameron JM, Al Maawali A, Blaser S, MacKay N, Robinson B, Raiman J. 2013. Complex II deficiency—A case report and review of the literature. Am J Med Genet Part A 161A:285–294.
Complex II deficiency—A case report and review of the literature†
Article first published online: 15 JAN 2013
Copyright © 2013 Wiley Periodicals, Inc.
American Journal of Medical Genetics Part A
Volume 161, Issue 2, pages 285–294, February 2013
How to Cite
Jain-Ghai, S., Cameron, J. M., Al Maawali, A., Blaser, S., MacKay, N., Robinson, B. and Raiman, J. (2013), Complex II deficiency—A case report and review of the literature. Am. J. Med. Genet., 161: 285–294. doi: 10.1002/ajmg.a.35714
- Issue published online: 24 JAN 2013
- Article first published online: 15 JAN 2013
- Manuscript Accepted: 15 SEP 2012
- Manuscript Received: 19 DEC 2011
- complex II;
- succinate dehydrogenase;
- mitochondrial disorder;
Complex II deficiency is a rare cause of mitochondrial respiratory chain defects with a prevalence of 2–23%. It is exclusively nuclear encoded and functions in the citric acid cycle by oxidizing succinate to fumarate and in the mitochondrial electron transport chain (ETC) by transferring electrons to ubiquinone. Of the four subunits, SDHA and SDHB are catalytic and SDHC and SDHD are anchoring. Mutations in SDHA and SDHAF1 (assembly factor) have been found in patients with CII deficiency and a mitochondrial phenotype. We present a patient with CII deficiency with a previously undescribed phenotype of dilated cardiomyopathy, left ventricular noncompaction, failure to thrive, hypotonia, and developmental delay. Also, a comprehensive review of 36 cases published in the literature was undertaken. The results show that CII deficiency has a variable phenotype with no correlation with residual complex activity in muscle although the phenotype and enzyme activities are comparable within a family. For some, the condition was fatal in infancy, others had multisystem involvement and some had onset in adulthood with mild symptoms and normal cognition. Neurological involvement is most commonly observed and brain imaging commonly shows leukoencephalopathy, Leigh syndrome, or cerebellar atrophy. Mutations in SDHAF1 are associated with leukoencephalopathy. Other organ systems like heart, muscle, and eyes are only involved in about 50% of the cases but cardiomyopathy is associated with high mortality and morbidity. In some patients, riboflavin has provided clinical improvement. © 2013 Wiley Periodicals, Inc.