Benefits of Testing

62-year-old male referred for genetic testing for macular disease

Original diagnosis: Pigmentary retinal disease vs Usher syndrome

Presenting complaint:

• Moderate dyschromatopsia
• Dry age-related macular degeneration in both eyes × 10-15 years

Family history: No known family history

Eye exam and imaging:

• Visual acuity: 20/25 OD and 20/30 OS
• Confrontation visual fields: concentric visual field restriction right > left
• Fundus significant for macular atrophy, drusen, trace pigment clumping
• Clinical diagnosis by ophthalmologist = inherited macular disease

Final diagnosis: Mitochondrial disorder associated with heteroplasmic (7%) MT-TL1 m.3243A>G variant

• The most common pathogenic variant in the mitochondrial genome being a molecular cause in up to 11.5% of individuals with mitochondrial disease
• Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS)

Key Takeaways

Mitochondrial disorders may not be included in all genetic testing panels, but can be associated with systemic manifestations.^[1] In these cases, it is important you refer your patient to a specialist for management.

This case study is based on a licensed genetic counsellor's in-office experience. It is based on a real patient with changes made for privacy considerations.