Abstract

MAKGOPA, Herbert et al. Maternally inherited diabetes and deafness with a variable presentation across three generations within a pedigree, South Africa. Afr. J. Lab. Med. [online]. 2024, vol.13, n.1, pp.1-5. ISSN 2225-2010.  http://dx.doi.org/10.4102/ajlm.v13i1.2384.

INTRODUCTION: Maternally inherited diabetes and deafness (MIDD) is caused by the m.3243A>G pathogenic variant in maternally inherited mitochondrial DNA. Diabetes is prevalent in our setting; however, MIDD is rarely diagnosed. This study, undertaken in Pretoria, South Africa, highlights the variable presentation of MIDD in different patients within the same family CASE PRESENTATION: A 45-year-old man (proband) with hearing impairment was referred to the endocrine unit in July 2015 due to poor glycaemic control (HbA1c = 13%). His clinical and biochemical features were in keeping with MIDD. A genetic study of accessible maternal relatives was pursued. His mother had difficulty hearing and reportedly died from an unspecified cardiovascular cause. Two sisters with diabetes and deafness died of cardiac-related conditions. One nephew had diabetes (HbA1c = 7.7%), hearing loss and tested positive for m.3243A>G. A third sister tested positive for m3243A>G, but aside from bilateral mild hearing loss in higher frequencies, showed no other signs of target organ damage. Her daughter developed end-stage kidney failure necessitating a transplant, while her son had no biochemical abnormalities and was negative for m.3243A>G MANAGEMENT AND OUTCOME: A multidisciplinary team managed and screened for complications of the patient and his maternal relatives. Proband died prior to genetic testing CONCLUSION: Most MIDD patients initially present with symptoms of diabetes only, and it is probable that many cases remain undiagnosed. A high index of suspicion is necessary when encountering a family history of both diabetes and impaired hearing, and screening should be offered to the patient's maternal relatives WHAT THE STUDY ADDS: This study demonstrates the importance of proper assessment when evaluating a patient with diabetes and a family history of hearing loss

Keywords : diabetes; mitochondrial DNA; maternally inherited diabetes and deafness; heteroplasmy; hearing loss.

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