Allergies and Genetics

Allergic conditions are very common in modern society and up to half of all children in the UK have been diagnosed with at least one of asthma, atopic eczema, hay fever or food allergies. With this increase in the prevalence of allergies, the development of these conditions is coming into question to help in the prevention and management.

Allergic Conditions

There are several allergic conditions that are often grouped together when discussing the link between allergies and genetics, including asthma, atopic eczema, hay fever or food allergies. These conditions appear to be linked and follow a similar pattern in relation to genetic susceptibility.

Children affected by allergies often follow a pattern where they will progress through a series of allergic conditions, known as the allergic march. For example, they may initially experience atopic eczema with then subsides, followed by the presentation of asthma and then rhinitis. Some children will also develop several of the allergic conditions and retain them for life

Familial Link

Some families appear to be more likely to be affected by allergic conditions than others and children born into these families have a higher risk of developing an allergic condition. This familial tendency to develop allergic conditions is thought to have a genetic link known as atopic.

It is estimated that more than half of children born into atopic families will develop an allergic disease, whereas the incidence of children with no family history of allergic disease is one in five. The risk is elevated even further for families where both parents are affected by an allergic condition.

Notably, children do not always develop the same allergic condition as the other members of the family and research tends to indicate a susceptibility to allergies, rather than a specific allergic condition.

Genetic Research

Genome-wide association studies (GWAS) have helped to enlighten our understanding of genes in the development of allergic conditions.

Specific gene variations that alter the encoding of epithelial cell-derived cytokines such as interleukin-33 and thymic stromal lymphopoietin may be involved in the pathogenesis of allergies. Additionally, variations in the ORMDL3 and GSDML genes have been linked to an increased risk of early-onset asthma.

These finding help to identify children with the highest susceptibility to allergies, which can be useful in targeting preventative techniques or being aware of allergies symptoms that require treatment.

However, there remains a lot to be discovered in the research field of allergies and genetics. Further studies are required to continue broadening the understanding of the genetic development mechanisms of allergic conditions, and begin to implement techniques to lessen the impact of allergies on the modern population.

Little-used measure of good cholesterol can predict heart attack and stroke risk

For decades, high-density lipoprotein (HDL) cholesterol has been dubbed "good cholesterol" because of its role in moving fats and other cholesterol molecules out of artery walls.

People with higher HDL cholesterol levels tend to have lower rates of cardiovascular disease, studies have shown.

Now, UT Southwestern scientists have analyzed data on more than 15,000 people to better understand the association between HDL cholesterol, heart attacks, and strokes in diverse populations.

They found that the number of HDL particles, a little-used measurement of HDL, is a more reliable predictor of heart attack and stroke risk than the standard HDL cholesterol metric.

Moreover, they found that among black people, neither HDL measurement was significantly associated with heart attack.

According to the Centers for Disease Control and Prevention, heart disease is the leading cause of death in the U.S. More than 12 percent of adults in the U.S. have high total cholesterol levels, and more than 18 percent have what's currently considered low levels of HDL cholesterol.

Cholesterol is a waxy substance that is used by the body to make hormones and keep cells functioning properly. But when low-density lipoprotein (LDL) cholesterol levels are too high, cholesterol can accumulate inside blood vessels, forming deposits called plaques.

These plaques can eventually lead to blood vessel blockages that cause heart attacks or strokes. HDL cholesterol helps remove cholesterol from blood vessels.

But recent studies have come to mixed conclusions about the association between HDL cholesterol levels and health outcomes.

For the new paper, published in the journal Circulation, Rohatgi and his colleagues pooled together information on people who had participated in four large, nationwide studies – the Dallas Heart Study, Atherosclerosis Risk in Communities study, Multi-Ethnic Study of Atherosclerosis, and the Prevention of Renal and Vascular Endstage Disease study.

In the study, people with the highest HDL-P levels, above 37 mmol/L, had a 37 percent lower risk of heart attack and a 34 percent lower risk of stroke than those who had the lowest HDL-P levels.

A better understanding of how HDL can help predict disease, and how that association varies among populations, is vital to lowering rates of cardiovascular disease, the researchers say.

 

 

БИЛЕТ 9

1. High Blood Pressure in Children. By Sally Robertson, B.Sc.

 

Although people usually assume that only middle-aged or elderly people develop high blood pressure (hypertension), it is also possible for the condition to arise in teenagers, children and even babies.

The American Heart Association advises that all children should be checked for high blood pressure on a yearly basis, as detecting the condition and treating it early will improve the child’s health and reduce or prevent the harmful effects of the condition.

Causes

Hypertension in children is usually caused by another underlying health condition such as heart disease or kidney disease. Itis therefore referred to as secondary hypertension and once the medical condition is resolved, the blood pressure typically returns to normal. Secondary hypertension may also be caused by the following conditions:

Hyperthyroidism

Adrenal disorder

Sleep problems, particularly sleep apnea

Renal artery stenosis

Some medications can increase blood pressure, but, again, the blood pressure usually returns to normal if the medication is discontinued.

In some cases, a doctor cannot determine what is causing the hypertension, in which case the condition is referred to as primary or essential hypertension. Various factors that are known to contribute to the risk of primary hypertension include:

Overweight or obesity (body mass index >25)

Family history of hypertension

High cholesterol and triglycerides

Type 2 diabetes or raised fasting blood sugar

Complications

Children with hypertension often develop sleep apnea and breathe abnormally while they sleep, particularly if the child is overweight. If the hypertension persists into adulthood, the person is at an increased risk of kidney disease, stroke, heart attack and heart failure.

Tests and diagnosis

Blood pressure is measured using an inflatable arm cuff and blood pressure gauge. The blood pressure measurement is made up of two readings. The first (upper) number is a measurement of systolic blood pressure, which is the pressure in the arteries when the heart beats. The second (lower) number is a measurement of the diastolic pressure, which is the pressure in the arteries between heartbeats.

One blood pressure measurement is not sufficient to diagnose hypertension. In order to be diagnosed, the child needs to have an abnormal reading on at least three visits to the doctor, and during a visit, the measurement may be taken several times to ensure it is accurate.

 

What is considered as “normal” blood pressure is relative and depends on the child’s gender, age and height. If hypertension is diagnosed, the child should then be checked approximately every six months. A doctor may also perform the following tests to check for other underlying conditions that may be causing the problem:

Echocardiogram to check blood flow through the heart

Ultrasound to assess the kidneys

Blood test to check blood cell counts, blood glucose and function of the kidneys

Urine analysis

Treatment

Hypertension in children is generally managed by making lifestyle changes such as exercising regularly, eating a diet that is good for the heart and maintaining a healthy weight. If these measures alone are not enough to resolve the problem, medications may be prescribed.