From Suspected Congenital Cytomegalovirus Infection to Malan Syndrome: Delayed Genetic Diagnosis Due to Diagnostic Anchoring

Background: Diagnostic anchoring to a presumed infectious etiology may delay recognition of underlying genetic disorders in children with neurodevelopmental impairment. Case presentation: A case of a child with sensorineural hearing loss, visual impairment, and developmental delay is reported; cytomegalovirus (CMV) infection was identified at 6 months of age based on positive serology and detection of viral DNA in serum and urine. Given the timing of testing, congenital CMV infection (cCMV) could not be definitively confirmed. Antiviral therapy with valganciclovir was administered. Despite antiviral treatment, severe neurodevelopmental impairment and hearing loss persisted, associated with facial dysmorphism, bilateral cryptorchidism, pectus excavatum, and optic nerve hypoplasia, findings not fully attributable to CMV infection. Brain magnetic resonance imaging (MRI) showed nonspecific findings. Chromosomal microarray analysis (CMA) performed at 4.5 years of age identified a heterozygous 908 kb de novo microdeletion at 19p13.2p13.13 containing NFIX (MIM *164005) and other morbid genes. The de novo variant was confirmed by parental testing, and the unifying genetic diagnosis of NFIX-related Malan syndrome (MIM#614753) was established. Conclusions: This case emphasizes the importance of reconsidering the initial diagnosis when the clinical phenotype is not fully consistent with an infectious etiology. Early genomic testing, including CMA, may facilitate timely recognition of underlying genetic syndromes in children with complex neurodevelopmental presentations.