Methods and compositions for detecting and diagnosing diseases and conditions

1. A method for selecting a heart failure subject for treatment with an aromatic-cationic peptide, the method comprising:

(a) detecting levels of monolysocardiolipin acyltransferase (MLCL AT1) or acyl-CoA lysocardiolipin (ALCAT1) mRNA in a biological sample from the subject;

(b) selecting the subject for aromatic-cationic peptide treatment where the level of MLCL AT1 or ALCAT1 mRNA in the biological sample from the subject is elevated about 2.5-fold compared to the normal control sample; and

(c) administering to the subject a therapeutically effective amount of the aromatic-cationic peptide, wherein the aromatic-cationic peptide is D-Arg-2′6′-Dmt-Lys-Phe-NH 2 or a pharmaceutically acceptable salt thereof.

2. The method of claim 1 , further comprising detecting levels of cardiolipin isoforms in a biological sample from the subject and comparing the levels of cardiolipin isoforms to those of a normal control subject, wherein the detecting levels of cardiolipin isoforms comprises chromatography, mass spectrometry, ELISA, Western blotting, immunodetection, or immunoprecipitation.

3. The method of claim 1 , wherein detecting the level of MLCL AT1 or ALCAT1 mRNA comprises RT-PCR, in situ hybridization, or Northern blotting.

4. The method of claim 1 , wherein the peptide is administered daily for 6 weeks or more.

5. The method of claim 1 , wherein the heart failure results from hypertension; ischemic heart disease; exposure to a cardiotoxic compound; myocarditis; thyroid disease; viral infection; gingivitis; drug abuse; alcohol abuse; pericarditis; atherosclerosis; vascular disease; hypertrophic cardiomyopathy; acute myocardial infarction; left ventricular systolic dysfunction; coronary bypass surgery; starvation; an eating disorder; or a genetic defect.

6. The method of claim 1 , wherein the peptide is administered orally, topically, systemically, intravenously, subcutaneously, intraperitoneally, or intramuscularly.

7. The method of claim 1 , further comprising separately, sequentially or simultaneously administering a cardiovascular agent to the subject, wherein the cardiovascular agent is selected from the group consisting of: an anti-arrhythmia agent, a vasodilator, an anti-anginal agent, a corticosteroid, a cardioglycoside, a diuretic, a sedative, an angiotensin converting enzyme (ACE) inhibitor, an angiotensin II antagonist, a thrombolytic agent, a calcium channel blocker, a throboxane receptor antagonist, a radical scavenger, an anti-platelet drug, a β-adrenaline receptor blocking drug, α-receptor blocking drug, a sympathetic nerve inhibitor, a digitalis formulation, an inotrope, and an antihyperlipidemic drug.

8. The method of claim 1 , wherein the biological sample comprises tissue, a cell, or a mitochondrion from the subject.