Discordant Keratoconus in Monozygotic Twins

Area of Science:

• Ophthalmology
• Genetics
• Environmental Health

Background:

• Keratoconus (KC) is a progressive corneal ectasia.
• The etiology of KC is multifactorial, involving genetic predisposition and environmental influences.
• Monozygotic twins provide a unique model to study gene-environment interactions.

Observation:

• A case of discordant keratoconus (KC) was observed in monozygotic twins.
• Twin one presented with bilateral, asymmetrical KC, linked to intense knuckle eye rubbing during night shifts and left-side sleeping.
• Twin two had healthy corneas, reporting minimal eye rubbing, daytime work, and a supine sleeping position.

Findings:

• Environmental and behavioral factors, specifically eye rubbing intensity, night work, and sleeping posture, appear to play a critical role in KC development.
• Despite identical genetic inheritance, significant differences in KC presentation were noted between the twins.
• The findings suggest that environmental exposures can modify genetic susceptibility to KC.

Implications:

• This case underscores the importance of considering environmental and lifestyle factors in KC pathogenesis.
• Understanding these modifiable risk factors may lead to novel strategies for KC prevention and management.
• Further research into gene-environment interactions in KC is warranted.