Eczema or atopic dermatitis (AD) makes the patient’s skin dry and itchy. It affects 20% of children and 3% of adults in high-income countries, and both genes and the environment have a significant influence on eczema’s development and severity. This study systematically investigates genetic-environment interactions and their role in AD risks.

The study focused on filaggrin (FLG) loss-of-function mutations and AD etiology. Medical databases like Embase, MEDLINE, and BIOSYS were systematically searched using AD and FLG synonyms. Statistical methods were beneficial in figuring out genetic and epidemiological effects. Nonrandomized and genetic studies assessed quality using criteria like power and guidance from ROBINS-I and Human Genome Epidemiology Network. After establishing the study design’s heterogeneity, the researchers conducted a meta-analysis.

For future research, the researchers identified a total of 1817 papers. A total of 12 studies qualified for formal interaction testing. Out of these, 6 studies had evidence for FLG-Environment interactions (P-value <= 0.05). The factors include early-life cat pets, water hardness, older siblings, prolonged breastfeeding, and phthalate exposure. The studies got hindered by low AD count ranging from 5 to 94. The variation in environmental exposure is also ambiguously defined.

The research conclusions on FLG-Environment interactions in AD etiology are limited. The sample sizes of the study were too small to assess the effects entirely.