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Biomarker Roundup No. 3

November 5, 2014

Cardiac System

Blood test may detect genes tied to atrial fibrillation
An international research team, headed by scientists from Lund University in Sweden, identified 12 genetic variants that are tied to atrial fibrillation. The discovery has led to the development of a blood test that looks for biomarkers that significantly increases the long-term risk of stroke, allowing doctors to better assess patients’ risks for the heart condition.

This test was created with the help of 27,400 individuals and their biospecimens who participated in a population study, including people formally diagnosed with atrial fibrillation. The researchers estimated that 1 in 5 individuals has a genetic variation that doubles their risk of atrial fibrillation when compared to people who do not have such a variation. This risk increase is likely as strong as that posed by high blood pressure.

When it came to stroke, the researchers estimated that the presence of these genetic variations among atrial fibrillation patients increased the likelihood of an event by 70 to 80 percent.

“The present results are one of several examples of how genetics research is not only an effective way of identifying new disease mechanisms, but can also have clinical applications and help doctors and patients to decide on the right tests and treatment,” Olle Melander of Lund University said in a statement.

Melander and colleagues noted that the prevalence of atrial fibrillation is rising as the global population ages.

Potassium channel gene linked to epilepsy
Epilepsy is a heterogeneous class of diseases in which individual patients can experience a variety of symptoms. Genetic research into the causes of different types of epilepsy is important to understanding and treating the condition and scientists continue to make more discoveries.

At Northwestern Medicine, researchers found that mutations in the KCNB1 potassium channel gene may lead to severe early onset epilepsy. This conclusion is based on whole exome sequencing tests they conducted on one child, as well as on unaffected relatives of hers. They found three types of mutations of the KCNB1 potassium channel gene associated with epileptic encephalopathy, which causes seizures and problems with cognition and motor development.

Further animal studies revealed that the risk increase is tied to actual genetic mutations and not simply missing gene functions. These results were confirmed in two other human patients.

Research on subtype of leukemia lays ground for drug evaluation
A multi-institutional study led by scientists from St. Jude Children’s Research Hospital revealed more about the disease processes that underlie a subtype of acute lymphoblastic leukemia (ALL) known as Philadelphia chromosome-like ALL, which affects more than one-fourth of young people with ALL. Specifically, they discovered that the prevalence of this subtype of ALL increases with age and that the rate of survival is poor.

These conclusions are based on the genomic sequencing of 42 individuals, as well as genomic and RNA sequencing of 136 leukemia patients’ cells. Results showed that 91 percent of these study subjects had genetic or chromosomal changes that impacted cytokine receptors or kinase signaling. These findings suggested that drugs known as tyrosine kinase inhibitors, which are typically used to treat adult patients, may be of value to pediatric cases of Ph-like ALL.

“The findings are tremendously exciting and pave the way for clinical trials testing TKIs plus chemotherapy in subsets of children and adolescents with ALL,” study co-author Stephen Hunger, M.D., said in a statement.

Clinical trials on the use of TKIs in children will begin late 2014 or early 2015.

Antibodies may predict kidney deterioration in autoimmune disease
A team of scientists from Maastricht University in The Netherlands demonstrated that monitoring the antibody levels of patients whose kidneys are affected by anti-neutrophil cytoplasmic antibody-associated (ANCA) vasculitis may help calculate the risk of relapse and kidney failure.

Individuals who have ANCA-associated vasculitis have an overactive immune system that sometimes attacks the blood vessels. Repeated or chronic attacks can damage several organ systems in the long term, including the kidneys.

To understand whether monitoring autoantibody levels is of value for patients, the researchers conducted an experiment that enrolled 166 ANCA-associated vasculitis patients, 104 of whom had kidney problems linked to autoimmune attacks. After 49 months of follow-up, the investigators recorded 89 increases in autoantibody levels and 74 disease relapses.

Among those with kidney problems, the risk of autoimmune relapse was 11 times higher when levels of autoantibodies increased. This relationship was weaker among ANCA-associated patients who did not have kidney problems.

“By measuring ANCA levels in patients with kidney involvement, doctors can predict which patients are going to relapse. It is expected that by using ANCAs as a guideline, severe relapses necessitating dialysis can be prevented,” study co-author Jan Willem Cohen Tervaert, M.D., Ph.D., said in a statement.