GWAS findings for human iris patterns: associations with variants in genes that influence normal neuronal pattern...

Area of Science:

• Genetics
• Developmental Biology
• Ophthalmology

Background:

• Human iris patterns exhibit significant variability.
• Understanding iris variation is crucial for ophthalmology, forensics, and developmental biology.
• Potential links between iris development and fundamental neurodevelopmental processes are of interest.

Purpose of the Study:

• To investigate the genetic underpinnings of human iris characteristics.
• To identify specific genes associated with iris crypt frequency, furrow contractions, pigmented ring presence, and nevus count.

Main Methods:

• Genome-wide association scans (GWAS) were conducted on three Australian samples of European descent.
• Four iris characteristics were analyzed: crypt frequency, furrow contractions, peripupillary pigmented ring, and number of nevi.
• Discovery and replication cohorts were utilized to validate findings.

Main Results:

• Significant associations were found between iris crypt frequency and variants in the axonal guidance gene SEMA3A (p = 6.6 × 10⁻¹¹).
• Furrow contractions were associated with variants in the cytoskeleton gene TRAF3IP1 (p = 2.3 × 10⁻¹²).
• The presence of a pigmented ring showed association with variants in the pigmentation gene SLC24A4 (p = 7.6 × 10⁻²¹).
• SEMA3A and TRAFIP1, implicated in neurogenesis and neural development, showed enrichment for iris crypts and furrows.

Conclusions:

• Genes involved in neuronal development, such as SEMA3A and TRAF3IP1, play a role in shaping human iris structures.
• Genetic factors influencing neurodevelopment may also contribute to iris morphology.
• These findings provide insights into the developmental origins of iris variation.