Cardiomyopathy, Dilated, 1gg

A number sign (#) is used with this entry because of evidence that this form of dilated cardiomyopathy is caused by homozygous mutation in the SDHA gene (600857).

For a general phenotypic description and discussion of genetic heterogeneity in dilated cardiomyopathy, see CMD1A (115200).

Clinical Features

Levitas et al. (2010) studied 15 Bedouin patients from a single tribe who presented with dilated cardiomyopathy (CMD) between the ages of 32 weeks' gestation and 10 years. Electrocardiography showed sinus rhythm with left ventricular hypertrophy and normal QTC intervals; echocardiography revealed left ventricular dilation in all patients, and 8 of the infants were also diagnosed with left ventricular noncompaction (LVNC1; see 604169). At presentation, all patients had normal growth and a normal neuromuscular examination, including muscle bulk and strength, reflexes, and gait. Psychomotor development was appropriate for age. During follow-up visits, neuromuscular examinations remained normal, and none of the patients had seizures. Brain MRI was performed in 2 patients and showed no evidence of focal lesions in the basal ganglia, gray matter, cortex, or brain stem, ruling out Leigh syndrome (256000). Mitochondrial respiratory chain enzymes were assessed in biopsies taken immediately postmortem from 3 patients, and showed moderately reduced activity of complex II in skeletal muscle (50 to 60% residual activity) with marked reduction of activity in cardiac muscle (15 to 18% residual activity).

Mapping

Of 15 Bedouin patients with neonatal dilated cardiomyopathy, all from the same tribe and sharing a family name, Levitas et al. (2010) traced 13 to 2 large consanguineous families showing a recessive pattern of inheritance; for 2 additional patients, family relations could not be established. A whole genome search for linkage in 1 family revealed a 5.6-cM segment of homozygosity that included the SDHA gene.

Molecular Genetics

In 15 Bedouin patients from a single tribe with neonatal dilated cardiomyopathy, Levitas et al. (2010) analyzed the candidate gene SDHA and identified homozygosity for a missense mutation (600857.0004).