Cardiomyopathy, Dilated, 1G

Alternative Names

  • CMD1G

Associated Genes

Titin
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WHO-ICD-10 version:2010

Diseases of the circulatory system

Other forms of heart disease

OMIM Number

604145

Mode of Inheritance

Autosomal dominant

Gene Map Locus

2q31.2

Description

CMD1G is a form of familial, non-syndromic, isolated, dilated cardiomyopathy characterized by ventricular chamber dilatation, systolic and diastolic dysfunction, and congestive heart failure.  Affected individuals may suffer from arrhythmia, dyspnea, fatigue, syncope, and swelling of the legs and feet.  The disorder usually has an onset in adulthood and many patients have been found to exhibit symptoms after the age of 40.  However, the condition can manifest at any age from infancy to late adulthood.  CMD1G accounts for 20% of all cases of familial dilated cardiomyopathy.

Diagnosis of CMD1G is made by first ruling out other causes of dilated cardiomyopathy such as ischemic injury, valvular and congenital heart disease, coronary artery disease etc., and then carrying out genetic analysis of the TTN gene.  Patients can be treated with pharmacological agents, pacemakers or defibrillators.  In severe cases, cardiac transplantation is required for individuals suffering from heart failure.  As a disorder with varied penetrance, prognosis of CMD1G varies even between family members.  Regular cardiovascular screening is recommended for asymptomatic carriers of known pathogenic TTN mutations as well as for first-degree relatives of affected individuals.

Molecular Genetics

The disorder follows an autosomal dominant pattern of inheritance and is caused by heterozygous mutations in the TTN gene.  This gene encodes titin, a protein that provides structure, flexibility and stability to the sarcomeres of cardiomyocytes.  Mutations in the TTN gene are speculated to impair chemical signaling and affect sarcomere function, thus reducing the heart’s ability to contract and weakening cardiac tissue.  So far, more than 50 mutations in TTN have been linked to the disorder.  Most of these occur in the C-terminal A-band of the titin protein.  TTN truncating mutations account for 25% of CMD1G cases. 

Epidemiology in the Arab World

View Map
Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
604145.1.1United Arab EmiratesUnknownNM_133378.4:c.9160G>C, NM_133378.4:c.74633C>THeterozygousAutosomal, RecessiveAl-Shamsi et al. 2016
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