Asthma genetics and intermediate phenotypes: a review from twin studies

Area of Science:

• Genetics
• Pulmonology
• Epidemiology

Background:

• Asthma and its phenotypes exhibit significant heritability, yet classical Mendelian inheritance patterns do not explain their transmission.
• Genome-wide screening, linkage, and association studies indicate the involvement of numerous genes in asthma pathogenesis.
• Twin studies have been instrumental in advancing the understanding of asthma genetics, with large-scale international studies yielding consistent findings.

Purpose of the Study:

• To highlight the significance of twin studies in elucidating the genetic underpinnings of asthma and its intermediate phenotypes.
• To emphasize the need for further twin research, particularly focusing on bronchial hyperresponsiveness, immunoglobulin E levels, and allergic sensitization.
• To explore the utility of twin designs, including monozygotic twins and co-twin controls, for dissecting gene-environment interactions in asthma.

Main Methods:

• Review of existing twin studies and their contributions to asthma genetics.
• Discussion of the application of monozygotic twins and co-twin control designs.
• Emphasis on the necessity of longitudinal twin studies for understanding age-related gene expression.

Main Results:

• Twin studies have provided substantial insights into the genetic basis of asthma.
• Comparable results across global twin studies underscore the heritability of asthma.
• Twin studies are well-suited to unravel the complex interplay between genetic factors and environmental influences in asthma.

Conclusions:

• Further twin studies are essential for investigating the genetic contribution to asthma intermediate phenotypes.
• Twin studies will be vital for identifying novel genes and understanding gene-environment interactions in asthma.
• Collaboration among research groups is crucial for advancing the understanding of asthma genetics.