Dual Cytomegalovirus and Rubella Immunoglobulin M positivity in a child with familial cataract: A diagnostic pitfall

TORCH serology is frequently used to evaluate paediatric cataracts but can be misleading beyond the neonatal period. We report a 2-year-old male with bilateral cataracts and dual IgM positivity for Cytomegalovirus (CMV) and Rubella. Despite initial infectious suspicion, negative CMV PCR and a significant maternal family history prompted genetic testing. Whole-exome sequencing identified an 11p13 duplication and GJA3 variants, confirming a hereditary etiology. This case highlights the microbiological challenge of IgM cross-reactivity and polyclonal activation. It underscores the necessity of clinicomicrobiological correlation and molecular confirmation to prevent misdiagnosing genetic conditions as active TORCH infections.