Method for detecting disease-associated mutations

Abstract

A method is described for diagnosing individuals as having hypertrophic cardiomyopathy, e.g. familial or sporadic hypertrophic cardiomyopathy. The method provides a useful diagnostic tool which becomes particularly important when testing asymptomatic individuals suspected of having the disease. Symptomatic individuals have a much better chance of being diagnosed properly by a physician. Asymptomatic individuals from families having a history of familial hypertrophic cardiomyopathy may be selectively screened using the method of this invention allowing for a diagnosis prior to the appearance of any symptoms. Individuals having the mutation responsible for the disease may be counseled to take steps which hopefully would prolong their life, i.e. avoid rigorous exercise. The methodology used in the above method also has broad applicability and may be used to detect other disease-associated mutations in DNA obtained from subject being tested for other disease-associated mutations.

Description

RELATED APPLICATIONS[0001]The present application is a continuation application of U.S. application Ser. No. 08 / 469,172, filed Jun. 6, 1995, pending, which is a continuation application of U.S. application Ser. No. 07 / 989,160, granted as U.S. Pat. No. 5,429,923, filed on Dec. 11, 1992. The contents of all of the aforementioned applications are hereby incorporated by reference.BACKGROUND[0002]The use of an individual's genetic information in the diagnosis of a disease is becoming more prevalent. Many diseases are caused by a defect in a single gene of an individual. All known autosomal dominant, autosomal recessive and x-linked disorders are believed to be caused by a defect in a single gene (Antonarakis, New England Journal of Medicine, Vol. 320, No. 3:153-63 (1981)). Genes responsible for some diseases or disorders have been cloned and characterized. The defect in the gene may be a gross gene alteration, a small gene alteration or even a point mutation. Examples of some diseases ca...

AI Technical Summary

Benefits of technology

[0006]The present invention provides a method for diagnosing individuals as having hypertrophic cardiomyopathy (hereinafter HC), e.g. familial or sporadic hypertrophic cardiomyopathy (hereinafter FHC or SHC). The method provides a useful diagnostic tool which becomes particularly important when screening asymptomatic individuals suspected of having the disease. Symptomatic individuals have a much better chance of being diagnosed properly by a physician. Asymptomatic individuals from families having a history of FHC may be selectively screened using the method of this invention allowing for a diagnosis prior to the appearance of any symptoms. Individuals having the mutation responsible for FHC may be counseled to take steps which hopefully would prolong their life, i.e. avoid rigorous exercise.

[0008]The present invention further pertains to a method for diagnosing familial hypertrophic cardiomyopathy. Prior to the present invention, there were no extensive studies involving a large number of families which established that this disease or disorder was caused by point mutations in the β cardiac myosin heavy-chain gene when the causative mutation is located within this gene. The process of diagnosing a disease caused by a point mutation is considerably more complex if multiple genes and multiple point mutations are responsible for the particular disease. FHC falls into this complex category because it is due to defects in the β cardiac myosin heavy-chain gene in approximately 50% of the families and unrelated families have different disease-causing point mutations. The present invention is based, at least in part, on the discovery that FHC is caused by point mutations when the mutation involves the β cardiac myosin heavy-chain gene and even further that different unrelated families have different disease-causing point mutations. The large size of the gene makes identifying disease-causing mutations laborious. The present invention provides a relatively rapid and easy method for accomplishing this difficult task.

[0010]The present invention also provides a non-invasive method for diagnosing HC that exploits the ectopic expression of this gene in nucleated blood cells, e.g., peripheral-blood mononuclear cells, allowing for access to β cardiac myosin heavy-chain transcripts from peripheral blood. Access to β cardiac myosin heavy-chain transcripts in peripheral blood permits efficient amplification of coding sequences which can be analyzed for small deletions, alternative splicing or point mutations with RNase protection assays. The non-invasive method for diagnosing HC involves obtaining a blood sample from a subject being screened for HC and isolating β cardiac myosin heavy-chain RNA from the blood sample. The subject is diagnosed for HC by detecting the presence or absence of an HC-associated mutation in the RNA as an indication of the subject having the disease. Mutations in the RNA may be detected by reverse transcribing the RNA into cDNA and subsequently detecting HC-associated mutations in the cDNA.

[0011]The present invention further provides a method that allows the detection of disease-causing mutations in a DNA sequence associated with a disease. Screening for a mutation in a person at risk for a particular disease can be accomplished rapidly and relatively easily through the presently described method. The method of this invention may be used to detect mutations responsible for diseases or disorders such as hypertrophic cardiomyopathy, e.g. familial or sporadic, cystic fibrosis, Gaucher's disease, hemophilia A and B, Duchenne's muscular dystrophy, sickle cell anemia, Tay-Sachs disease, and phenylketonuria.

Problems solved by technology

The large size of the gene makes identifying disease-causing mutations laborious.

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