NMNAT1 variants cause cone and cone-rod dystrophy

Area of Science:

• Ophthalmology
• Genetics
• Molecular Biology

Background:

• Cone and cone-rod dystrophies (CD and CRD) are inherited retinal diseases primarily impacting cone photoreceptors.
• The genetic cause remains unidentified in a significant portion of autosomal recessive CD and CRD cases.
• NMNAT1 gene variants are known to cause Leber congenital amaurosis (LCA), a severe early-onset retinal dystrophy.

Observation:

• Two patients presenting with clinical features of CD and CRD were studied.
• Genetic analysis revealed distinct NMNAT1 variants in both patients: a homozygous variant in Case 1 and compound heterozygous variants in Case 2.
• Both patients exhibited macular atrophy alongside their diagnosed retinal dystrophy.

Findings:

• The identified NMNAT1 variants were confirmed as disease-causing through detailed analysis and correlation with the observed phenotypes.
• This study establishes a link between NMNAT1 variants and the development of CD or CRD, particularly when accompanied by macular atrophy.
• The specific homozygous and compound heterozygous variants identified represent novel findings in the context of these retinal dystrophies.

Implications:

• The findings suggest that NMNAT1 should be included in the genetic testing panel for individuals diagnosed with CD or CRD.
• Expanding the known genotype-phenotype correlations for NMNAT1 may improve diagnostic accuracy for retinal degenerative diseases.
• Further research into the functional consequences of these NMNAT1 variants could elucidate disease mechanisms and inform therapeutic strategies.