Diagnostics for pulmonary arterial hypertension and sudden cardiac death

1. A method for diagnosing pulmonary hypertension (PH) or a risk of developing PH in a subject comprising

(a) providing a test sample from said subject, wherein said test sample comprises a circulating cell of whole blood;

(b) assaying the level of a full-length SCN5A protein-encoding mRNA or a SCN5A splice variant protein-encoding mRNA in the test sample; and

(c) diagnosing the subject with PH or a risk of developing PH if (i) the level of the full-length SCN5A protein-encoding mRNA is reduced in the subject compared to a normal control, or (ii) the level of the mRNA encoding the SCN5A splice variant is increased by at least 4-fold compared to a normal control.

2. The method of claim 1 , wherein (i) the level of the full-length SCN5A protein-encoding mRNA is reduced in the subject compared to a normal control, or (ii) the level of mRNA encoding the SCN5A splice variant is increased compared to a normal control indicates a diagnosis of PH.

3. A method for identifying whether a subject afflicted with PH is at risk of dying from sudden cardiac death (SCD), comprising

(a) providing a test sample from said subject, wherein said test sample comprises whole blood;

(b) assaying the level of a full-length SCN5A protein-encoding mRNA or a SCN5A splice variant protein-encoding mRNA in the test sample; and

(c) (1) comparing the level determined in (b) to a value in a database to identify the subject's absolute or relative risk of suffering from SCD, or (2) identifying the subject is at risk of suffering from SCD if the level of the SCN5A splice variant protein-encoding mRNA is at least about 4-fold greater in the subject compared to a normal control.

4. The method of claim 3 , wherein the database contains

(a) level values of full-length SCN5A protein-encoding mRNA or SCN5A splice variant protein-encoding mRNA from (i) subjects who have suffered from SCD, (ii) subjects who are afflicted with PH but who have not suffered from SCD, (iii) subjects afflicted with PH for at least about 1, 2, 3, 4, 5, 10, 15, or 20 years without suffering from SCD, and/or (iv) subjects who are not afflicted with PH, and/or

(b) mean or median level values calculated using full-length SCN5A protein-encoding mRNA or SCN5A splice variant protein-encoding mRNA level values from (i) subjects who have suffered from SCN5A, (ii) subjects who are afflicted with PH but who have not suffered from SCD, (iii) subjects afflicted with PH for at least about 1, 2, 3, 4, 5, 10, 15, or 20 years without suffering from SCD, and/or (iv) subjects who are not afflicted with PH.

5. The method of claim 3 , further comprising administering a treatment to the subject if the subject is identified as being at risk of suffering from SCD.

6. The method of claim 3 , further comprising directing the subject to obtain additional screening for SCD risk based on the level of the full-length SCN5A protein-encoding mRNA or SCN5A splice variant protein-encoding mRNA in the test sample.

7. A method of SCD treatment, comprising identifying a subject at risk of suffering from SCD according to the method of claim 3 , and administering to the subject a treatment for SCD.

8. The method of claim 7 , wherein the treatment for SCD comprises administration of an antiarrhythmic drug, an angiotensin converting enzyme inhibitor (ACE), an angiotensin II receptor blocker, a beta-blocker, digoxin, a diuretic, a blood vessel dilator, an aldactone inhibitor, or a calcium channel blocker to the subject.

9. The method of claim 7 , wherein the treatment for SCD comprises implantation of a cardioverter-defibrillator (ICD) or surgery to repair or replace a mitral valve or an aortic valve in the subject.

10. The method of claim 1 , wherein the PH is pulmonary arterial hypertension (PAH).

11. The method of claim 1 , wherein the SCN5A splice variant is E28B, E28C and/or E28D, or wherein the SCN5A splice variant is two or more splice variants, and the two or more splice variants comprise one or more of E28B, E28C, and E28D.

12. The method of claim 1 , further comprising

(a) determining the level of one or more of HIF-1α, AngII, LUC7L3, RBM25, and/or PERK in the test sample;

(b) assaying whether the subject comprises mitochondrial aerobic glycolysis; or

(c) assaying whether the subject comprises mitochondrial aerobic glycolysis, wherein said assaying comprises 2-deoxy-2( 18 F)flouro-D-glucose positron emission tomography (FDG-PET).

13. The method of claim 1 , wherein assaying the level of the full-length SCN5A protein-encoding mRNA or the SCN5A splice variant protein-encoding mRNA comprises contacting the full-length SCN5A protein-encoding mRNA or the SCN5A splice variant protein-encoding mRNA with a SCN5A-specific binding agent.

14. The method of claim 13 , wherein the binding agent comprises an antibody or a fragment thereof, a detectable protein or a fragment thereof, or a nucleic acid molecule.

15. The method of claim 14 , wherein

(a) the nucleic acid molecule comprises at least one probe or at least one primer;

(b) the assaying comprises a polymerase chain reaction (PCR), reverse transcription polymerase chain reaction (RT-PCR), quantitative PCR (qPCR), or a Northern Blot;

(c) assaying the level of the full-length SCN5A protein-encoding mRNA or the SCN5A splice variant protein-encoding mRNA comprises reverse-transcribing cDNA from the full-length SCN5A protein-encoding mRNA or the SCN5A splice variant protein-encoding mRNA;

(d) the binding agent comprises an antibody;

(e) the binding agent comprises an antibody wherein the antibody comprises an anti-full-length SCN5A and/or an anti-SCN5A splice variant antibody;

(f) the binding agent comprises an antibody, wherein the antibody comprises conjugated to a detectable moiety;

(g) the binding agent comprises an antibody wherein said antibody comprises a polyclonal antibody or a monoclonal antibody;

(h) wherein said binding agent is attached to a solid support;

(i) wherein said binding agent is attached to a solid support, wherein said solid support comprises a strip, a multiwell plate, a microarray, a polymer, a bead, or a nanoparticle;

(j) wherein the binding agent comprises a detectable moiety, and the detectable moiety comprises a fluorescent marker, a radioactive isotope, or a chemiluminescent compound;

(k) wherein the binding agent comprises a detectable moiety, and the detectable moiety comprises a fluorescent marker, a radioactive isotope, or a chemiluminescent compound, wherein the detectable moiety comprises a fluorescent marker, and the fluorescent marker comprises fluorescein isothiocyanate, rhodamine, phycoerythrin, phycocyanin, allophycocyanin, p-phthaldehyde and fluorescamine, or 152 Eu;

(l) wherein the binding agent comprises a detectable moiety, and the detectable moiety comprises a fluorescent marker, a radioactive isotope, or a chemiluminescent compound, wherein the detectable moiety comprises a radioactive isotope, and the radioactive isotope is 125 iodine, tritium, 75 selenomethonine, or 64 copper; or

(m) wherein the binding agent comprises a detectable moiety, and the detectable moiety comprises a fluorescent marker, a radioactive isotope, or a chemiluminescent compound, wherein the detectable moiety comprises a chemiluminescent compound, and the chemiluminescent compound is luminol, isoluminol, theromatic acridinium ester, imidazole, acridinium salt, or oxalate ester.