RESUMO
Background: Marfan syndrome (MFS) is a multisystem connective tissue disorder involving the cardiovascular, skeletal, and ocular systems. Case Report: We present a case of a 15-year-old boy who was sent to the ophthalmologist for the checkup of the primary disease-hypercalciuria and gigantism for the first time at the age of 5.5 years. After the ophthalmological examination (low myopia <-3.0 diopters, ectopic lens with defects in the nasal lens zonules detected by ultrasound biomicroscopy) and owing to gigantism, suspecting of MFS, we referred the patient for further diagnosis, treatment, and follow-ups. Conclusion: The child's excessive growth pointed to the presence of gigantism in the very beginning. A duly identified problem of MFS in our patient at an early age contributed to the correct diagnosis and prevention of the development of amblyopia in the child.