Methods for profiliing and quantitating cell-free rna

Abstract

The invention generally relates to methods for assessing a neurological disorder by characterizing circulating nucleic acids in a blood sample. According to certain embodiments, methods for assessing a neurological disorder include obtaining RNA present in a blood sample of a patient suspected of having a neurological disorder, determining a level of RNA present in the sample that is specific to brain tissue, comparing the sample level of RNA to a reference level of RNA specific to brain tissue, determining whether a difference exists between the sample level and the reference level, and indicating a neurological disorder if a difference is determined.

What is claimed is: 
     
         1 . A method for characterizing a neurological disorder of a patient, the method comprising:
 obtaining RNA from a blood sample of a patient suspected of having a neurological disorder;   converting the RNA obtained in the sample into cDNA;   determining a level of the sample cDNA that corresponds to RNA originating from brain tissue;   comparing the level of the sample cDNA to a reference level of circulating RNA originating from brain tissue; and   indicating a neurological disorder based upon a statistically-significant deviation between the level of sample cDNA and the reference level.   
     
     
         2 . The method of  claim 1 , further comprising the step of determining a stage of the indicated neurological disorder. 
     
     
         3 . The method of  claim 2 , wherein the stage is selected from the group consisting of no cognitive impairment, mild cognitive impairment, moderate cognitive impairment, and severe cognitive impairment. 
     
     
         4 . The method of  claim 1 , wherein the neurological disorder is Alzheimer's disease. 
     
     
         5 . The method of  claim 1 , wherein the level of the sample cDNA and the reference level correspond to an amount of circulating RNA released from brain tissue selected from the group consisting of spinal cord, pituitary, hypothalamus, thalamus, corpus callosum, cerebrum, cerebral cortex, and combinations thereof. 
     
     
         6 . The method of  claim 1 , further comprising the step of monitoring progression of the neurological disorder by repeating the steps of obtaining through comparing. 
     
     
         7 . The method of  claim 1 , wherein the reference level comprises a level of cDNA corresponding to a patient population without cognitive impairment. 
     
     
         8 . The method of  claim 1 , wherein the reference level comprises a level of cDNA corresponding to a patient population diagnosed with a neurological disorder. 
     
     
         9 . The method of  claim 1 , wherein the blood sample is plasma or serum. 
     
     
         10 . The method of  claim 1 , wherein the determining step is performed via a sequencing technique, a microarray technique, or both. 
     
     
         11 . A method for characterizing a neurological disorder of a patient, the method comprising:
 obtaining RNA from a blood sample of a patient suspected of having a neurological disorder,   converting the RNA obtained in the sample into cDNA;   determining a level of the sample cDNA that corresponds to RNA originating from brain tissue;   comparing the level of the sample cDNA to a set of variables correlated with a neurological disorder, wherein the variables comprise reference levels of cDNA that correspond to circulating RNA originating from brain tissue and to one or more stages of the neurological disorder; and   indicating a stage of a neurological disorder of the patient based upon a statistically significant deviation between the level of the sample cDNA and the set of variables correlated with a neurological disorder.   
     
     
         12 . The method of  claim 11 , wherein the reference levels of cDNA further correspond to patient populations of certain ages. 
     
     
         13 . The method of  claim 11 , wherein the level of the sample cDNA and reference levels of cDNA correspond to an amount of circulating RNA released from brain tissue that is selected from the group consisting of pituitary, hypothalamus, thalamus, corpus callosum, cerebrum, cerebral cortex, and combinations thereof. 
     
     
         14 . The method of  claim 11 , further comprising monitoring progression of the neurological disorder by repeating the detecting step through the indicating step at a future time. 
     
     
         15 . The method of  claim 11 , wherein the stages are selected from the group consisting of no cognitive impairment, mild cognitive impairment, moderate cognitive impairment, and severe cognitive impairment. 
     
     
         16 . The method of  claim 11 , wherein the neurological disorder is Alzheimer's disease. 
     
     
         17 . The method of  claim 11 , wherein the blood sample is plasma or serum. 
     
     
         18 . The method of  claim 11 , wherein the determining step is performed via a sequencing technique, a microarray technique, or both. 
     
     
         19 . A method of characterizing a neurological disorder, comprising the steps of
 obtaining RNA from a blood sample of a patient suspected of having a neurological disorder;   determining a level of RNA present in the sample that is specific to brain tissue;   comparing the sample level of RNA to a reference level of RNA specific to brain tissue;   determining whether a difference exists between the sample level and the reference level; and   indicating a neurological disorder if a difference is determined.   
     
     
         20 . The method of  claim 19 , further comprising the step of determining a stage of the indicated neurological disorder. 
     
     
         21 . The method of  claim 19 , wherein the stage is selected from the group consisting of no cognitive impairment, mild cognitive impairment, moderate cognitive impairment, and severe cognitive impairment. 
     
     
         22 . The method of  claim 19 , wherein the neurological disorder is Alzheimer's disease. 
     
     
         23 . The method of  claim 19 , wherein the level of sample RNA and the reference level of RNA correspond to an amount of circulating RNA released from brain tissue selected from the group consisting of pituitary, hypothalamus, thalamus, corpus callosum, cerebrum, cerebral cortex, and combinations thereof. 
     
     
         24 . The method of  claim 19 , further comprising the step of monitoring progression of the neurological disorder by repeating the steps of obtaining through comparing at a future time. 
     
     
         25 . The method of  claim 19 , wherein the reference level of RNA corresponds to a patient population diagnosed with a neurological disorder. 
     
     
         26 . The method of  claim 19 , wherein the blood sample is plasma or serum. 
     
     
         27 . The method of  claim 19 , wherein the determining step is performed via a sequencing technique, a microarray technique, or both. 
     
     
         28 . A method for identifying one or more biomarkers associated with a neurological disorder, the method comprising
 obtaining RNA present in a blood sample of a patient suspected of having a neurological disorder;   converting the RNA in the sample into cDNA;   determining levels of the sample cDNA that corresponds to RNA originating from brain tissue;   comparing the levels of the sample cDNA to one or more reference levels that correspond to circulating RNA originating from brain tissue; and   identifying as a biomarker for a neurological disorder a level of sample cDNA that is statistically different from a reference level.