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A female individual with symptoms of the Maternally Inherited Diabetes and Deafness syndrome (MIDD) was diagnosed positive for the A3243G mutation in her mitochondrial DNA. Heteroplasmy levels were 18% in DNA from leucocytes and 55% in oral mucosa DNA. This finding corroborates the diagnosis of MIDD. Normally, this mutation is present in all the individuals within the maternal lineage of the pedigree. In this particular pedigree the mutation was undetectable in the mother of the proband and her three brothers. Paternity testing using polymorphic chromosomal DNA markers supported the assumed family relationship. We conclude that we are dealing in this proband with the de novo appearance of the A3243G mutation that has reached high heteroplasmy values in at least two tissues within one generation. This observation supports the hypothesis that during embryogenesis mitochondrial DNA goes through a genetic bottleneck with a limited number of segregating units.

Left ventricular function of 20 diabetic patients was investigated at rest and during hand-grip test using radionuclide ventriculography. The aim of the study was to discuss the correlation of cardiac function with autonomic cardiac neuropathy (ACN) in diabetic subjects. ACN was tested using heart rate response to valsalva maneuver, standing up, deep breathing; blood pressure response to standing up, sustained hand-grip, and additionally corrected QT(QTc) measurements. Plasma glucose regulation was screened with fructosamine levels. Ejection fraction (EF), peak ejection (PER) and filling rates (PFR), times to peak ejection (TPE) and filling (TPF), time to endsystole (TES), TES/T, TPE/T, TPF/T, 1/3 PER, 1/3 PFR, 1/3 EF, 1/3 FF (filling fraction) we calculated. Thirteen patients had ACN. Six patients (30%) had a low EF at rest. As a response to hand-grip, 14 patients (70%) showed a decrease in EF (9 ACN). PFR was low in 10 patients (50%) at rest and in 12(60%) during hand-grip. The mean rest PER value of ACN+ patients (4.4 ± 1.3) was significantly higher than that of controls (2.9 ± 0.5) and patients without ACN (3.4 ± 0.4; p < 0.05) as well as the mean 1/3 PER value (1.7 ± 0.5 vs. 1.3 ± 0.5; p < 0.05). Fourteen patients (70%) had a fall in PER 10 ACN) as a response to hand-grip. The mean TES/T value of patients with ACN (0.44 ± 0.05) was significantly higher than of those without ACN (0.38 ± 0.05; p < 0.05). In conclusion, diastolic dysfunction was detected frequently at rest. Systolic parameters were markedly impaired as a response to handgrip in patients with ACN. Sympathetic overactivity was noted in ACN+ group at rest. Our results indicated that the patients with diabetes and ACN have subclinical left ventricular diastolic dysfunction and symphatic overactivity.