Genetic & Environmental Factors That Causes Eczema

Eczema, also known as atopic dermatitis, can affect up to 1 in 5 children and is also relatively common in adults.^[1] In this skin condition, children often develop inflamed red rashes that scale and can be severely itchy. Unfortunately, many of these children have poor sleep due to constant scratching and some even develop learning disabilities and behavioral problems.

The cause of eczema is complex and consists of many factors including genetics, immune system problems, and environmental factors that can weaken the outer skin barrier.^[2] It is common for parents to wonder if their child’s eczema is a result of something in the household, in their diet, or if it is genetic. Although physicians and scientific investigators do not know the exact cause, scientific knowledge is expanding regarding certain contributing factors in eczema.

The Role of Genetic Factors in Eczema: Father vs Mother?

Scientific evidence suggests that the genetics of the parents could influence the development of eczema in children.^[3,4] There is controversy regarding whether the genetics of the mother or the father has a greater influence on the eczema risk in children. While one study found that babies who had a mother with eczema had almost a 4-times higher risk for developing eczema,^[5] a separate study found that there was an equal risk for the baby to develop eczema if either the mother or the father had eczema.^[6] There are thousands of different genes and a complex network of immune system proteins involved in eczema, making it nearly impossible to pinpoint specific genetic variants that could lead to eczema.

Filaggrin mutations and increased eczema risk

The filaggrin gene codes for the filaggrin protein, which is crucial in the normal development of the epidermis, for strong skin barrier function, and to maintain hydration and protection. Researchers discovered that in mothers with a filaggrin gene mutation, their children had a 1.5-fold increased risk of developing eczema.^[4]

Is the risk for eczema linked to certain chromosomes?

Genetic testing has revealed that eczema risk may be traced to certain chromosomes, including chromosome 1,3,5,13,15, and 17.^[7-9] Although the exact locations, referred to as “loci,” on the chromosomes have not been identified, it is possible that increased risk for eczema could be passed down from either the mother or the father.

Environmental Factors in Eczema

When a baby is first born, their immune system is not yet fully developed and various environmental factors may increase the odds for the baby to develop eczema. Some factors can even influence the prenatal environment before the baby is born, possibly increasing the risk for eczema.

Maternal nutrition

Maternal diet during pregnancy and breastfeeding is gaining recognition as an important factor in the pathogenesis of eczema. Current research is vast, with multiple factors including breastfeeding, supplements, vitamin and mineral status playing a potential role in eczema. Below is a summarized list of evidence for the role of maternal nutrition in eczema:

• Eczema improved after breastfeeding mothers removed eggs and cows’ milk from their diets^[10]
• Mothers who ate a high vegetable diet during pregnancy had two-year-olds with a lower risk of eczema^[11]
• Probiotic supplementation during pregnancy may reduce eczema in babies^[12,13]
• Mothers who took a vitamin E supplement during pregnancy had a significantly reduced risk for having babies that developed eczema^[14]

Breastfeeding and protection against eczema

Overall, there is conflicting evidence regarding whether or not breastfeeding prevents eczema. Although there is a greater majority of evidence supporting that breastfeeding prevents eczema,^[15,16] evidence also exists that failed to show a connection.^[17,18]

Maternal age and risk for eczema remains unclear

Some research suggests that mothers over the age of 35 years old have an increased risk for having babies who develop eczema,^[19] while other research found no connection between maternal age and risk for eczema.^[20]

Tobacco and alcohol increase the risk for eczema

• Babies born to mothers who smoked during pregnancy had a doubled risk for developing eczema^[21]
• There is a significant association between maternal alcohol consumption during pregnancy and having a baby that develops eczema^[22]

Family socioeconomic status

There is a common link between eczema and low socioeconomic status, such as poverty, inconsistent parenting situations, and poor health in children and adolescents.  Interestingly, eczema is quite the opposite. Researchers have found that parents with higher socioeconomic status (higher income and resources) have an increased risk for eczema in their children.^[23,24] These results are surprising, and one hypothesis may be that children born into a lower socioeconomic status may be exposed to more microbes and infections that lead to greater development of the immune system, something referred to as the hygiene hypothesis.^[25]

Furry friends prevent eczema

If your child with eczema is asking for a puppy, you may want to give in and get one! Some evidence suggests that early exposure to furry pets actually reduces the risk of developing eczema.^[26] Studies have shown protective effects in families with dogs, while some evidence shows that early exposure to cats is not protective against eczema.^[27]

Bottom Line

As you can see, there are many factors contributing to eczema and research continues to reveal further internal and environmental contributors. There is an undeniable genetic association in eczema, especially in children who have one or more parents with eczema. However, there is still a lot to learn in terms of specific genes and heritability patterns. By understanding the environmental factors that contribute to eczema, doctors can help parents to identify and modify lifestyle factors that may help to improve symptoms in their children.