Susceptibility gene for Alzheimer's disease

1. A method for indicating the pre-disposition of a male human subject to developing Alzheimer's disease, which method comprises the steps of:

(A) genotyping said subject for the p21E2c31 polymorphism in the p21cip 1 gene by determining whether said subject possesses the variant A allele of said p21E2c31 polymorphism; and

(B) using the results of said genotyping to indicate the pre-disposition of said subject to Alzheimer's disease, wherein the presence of said variant A allele of said p21E2c31 polymorphism indicates that said subject is pre-disposed to developing Alzheimer's disease.

2. The method of claim 1 , wherein said method further comprises determining whether said subject possesses the variant T allele of the p21E3+20C/T polymorphism in the p21cip1 gene, wherein the presence of said variant T allele of said p21E3+20 C/T polymorphism is further indicative that said subject is predisposed to developing Alzheimer's disease.

3. A method for diagnosing Alzheimer's disease in a male human subject exhibiting clinical symptoms of Alzheimer's disease, which method comprises the steps of:

(A) genotyping said subject for the p21E2c31 polymorphism in the p21cip1 gene by determining whether said subject possesses the variant A allele of said p21E2c31 polymorphism; and

(B) using the results of said genotyping to diagnose Alzheimer's disease in said subject, wherein the presence of said variant A allele of said p21E2c31 polymorphism is diagnostic that said subject has Alzheimer's disease.

4. The method of claim 3 , wherein said method further comprises determining whether said subject possesses the variant T allele of the p21E3+20 C/T polymorphism in the p21cip1 gene, wherein the presence of said variant T allele of said p21E3+20 C/T polymorphism is further diagnostic that said subject has Alzheimer's disease.

5. A method of determining the existence of a genetic basis for Alzheimer's disease in a male human subject, which method comprises the steps of:

(A) genotyping said subject for a genetic variation, said genetic variation comprising the variant A allele of the p21E2c31 polymorphism of the p21cip1 gene; and

(B) using the results of said genotyping to determine whether the genetic variation in said subject contributes to the genetic basis for Alzheimer's disease in the subject, wherein the presence of said variant A allele of said p21E2c31 polymorphism indicates that a genetic variation that contributes to the genetic basis for Alzheimer's disease is present in said subject.

6. The method of claim 5 , wherein said method further comprises determining whether said subject possesses the variant T allele of the p21E3+20 C/T polymorphism in the p21cip1 gene, wherein the presence of said variant T allele of said p21E3+20 C/T polymorphism is further indicative indicates that a genetic variation that contributes to the genetic basis for Alzheimer's disease is present in said subject.

7. A method of determining the existence of a genetic basis for earlier onset of Alzheimer's disease in a female human subject exhibiting clinical symptoms of Alzheimer's disease, which method comprises the steps of:

(A) genotyping said subject for a genetic variation, said genetic variation comprising the variant A allele of the p21E2c31 polymorphism of the p21cip1 gene; and

(B) using the results of said genotyping to determine whether the genetic variation in said subject contributes to the genetic basis for Alzheimer's disease in the subject, wherein the presence of said variant A allele of said p21E2c31 polymorphism indicates that a genetic variation that contributes to the genetic basis for earlier onset of Alzheimer's disease is present in said subject.