A Blood Test for Suicide

May 2, 2014

By Medical Discovery News

The 10th leading cause of death in America is completely preventable – suicide.  In 2010, 38,364 people died by suicide, more than chronic liver disease, septicemia, and Parkinson’s disease.

While strongly linked to depression, there are not always clear warning signs that someone is about to commit suicide. Unlike a viral or bacterial infection where there can be a number of signs like changes in body temperature, white blood cells, and signaling molecules, there is no simple clinical test to diagnose suicidal tendencies. Now, new research is working toward a blood test using biomarkers that may identify those likely to commit suicide. 

Biomarkers are biological materials that are seen under specific conditions. For example, during a viral infection proteins called cytokines are produced by the human body to help defend cells and tissues from the virus. Identifying these proteins is a signature of viral infection. The challenge is that these signatures change over the course of the infection and different viruses can produce different signatures. Scientists have been working extensively to use this concept of biomarkers to help with the early detection of other diseases from cancer to Alzheimer’s. 

Researchers at the University of Indiana want to design a simple blood test to detect a specific biomarker to identify those who might be at risk for suicide. They have been looking for protein biomarkers that can distinguish different psychological states. For example, can specific biomarkers tell if someone with bipolar disorder is in a high or low mood? In this recent study, researchers looked for biomarkers in individuals contemplating suicide. Every three to six months, they interviewed and drew blood from their subjects – 75 men with bipolar disorder – and rated their risk of suicide from low to high. Several proteins in the blood varied with these mood swings but one in particular caught researchers’ attention. The protein SAT1 was present in all of those with high indications of suicidal thoughts. SAT1 plays a role in the body’s response to stressful situations.

They then tested suicide victims, grouping them by age and gender, and found high levels of SAT1 in all of them. Finally, they took blood samples regularly from about 80 men with either schizophrenia or bipolar disorder. The study showed higher SAT1 levels in those who were later hospitalized for suicidal behavior. The presence of elevated SAT1 was more than 80 percent predictive of hospitalization. Overall, these are promising results.

SAT1 is not an absolute signature for suicide because many things that can affect its levels. And like any complex behavior, there are a multitude of factors involved. Other biomarkers will need to be identified to create a biosignature for suicide. But this is an exciting discovery that may be used to prevent the tragic deaths of many people in the future.   

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A Risk-Free Test for Down’s

April 18, 2014

By Medical Discovery News

Keep Calm, It's Only An Extra Chromosome

When it comes to chromosomes, extra copies are not a good thing. Every cell in the human body carries the same genetic information in two copies of 23 chromosomes. Having an extra copy of a chromosome is called trisomy, and an extra copy of chromosome number 21 is what causes Down syndrome.

Physical signs of Down syndrome include upward slanting of the eyes, flattened facial features, small and unusually shaped ears, small heads, and broad hands with short fingers. Down syndrome can also cause more serious conditions such as varying degrees of mental retardation, poor muscle tone, an increased risk of early onset dementia, and heart, stomach, and eye problems. No two cases of Down syndrome are the same, and with therapy and support people with Down syndrome can live long, productive lives.

The risk of Down syndrome increases with the mother’s age during pregnancy. The risk of having a baby with Down syndrome increases from one in 1,300 to one in 25 at ages 25 to 49.

Women who are pregnant with a child who might have Down syndrome typically undergo an ultrasound test and blood tests for markers such as pregnancy-associated plasma protein-A and a hormone known as human chorionic gonadotropin. Abnormal levels of these markers may indicate a problem with the baby. These tests are generally done during weeks 11-13 of pregnancy. The American College of Obstetrics and Gynecology now recommends that all women undergo prenatal testing for chromosomal abnormalities.

Until recently, Down syndrome could only be confirmed by invasive tests that collect cells from the amniotic fluid surrounding the fetus, the placenta, or the fetus itself. These tests can be risky, with a one percent chance of miscarriage. However, a new, noninvasive screening test called circulating cell-free fetal DNA analysis may reduce the need for invasive prenatal tests. Circulating cell-free DNA from the fetus makes up three to 13 percent of the DNA fragments circulating in the mother’s bloodstream during pregnancy.

First, DNA is isolated from the mother’s plasma, the liquid component of blood. Then, there are two ways to determine if there are any chromosomal abnormalities. Massive parallel DNA genomic sequencing can be used to quantify millions of DNA fragments in just a few days and can accurately detect trisomies. Another approach is called Digital Analysis of Selected Regions, which analyzes only the chromosomes in question to evaluate them for any abnormalities.    

These tests are 99 percent accurate, can be done as early as the 10th week of pregnancy, and are more reliable. They can also diagnose other trisomies, like the ones that affect chromosome 18 (Edwards syndrome) and chromosome 13 (Patau syndrome). At this stage, invasive testing is still required to confirm the diagnosis of a trisomy. But in the near future this new technology will reduce or eliminate the need for additional invasive tests that put the fetus at risk. This is only the beginning of the development of safer and more accurate genetic tests.

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