Pathogenic Presentation of a Variant of Uncertain Significance in a Puerto Rican Patient With Wiedemann-Steiner Syndrome.

Wiedemann-Steiner syndrome (WDSTS) is an autosomal dominant disorder that is caused by mutations in the KMT2A gene. This case reports a two-year-old male's diagnosis of WDSTS via a heterozygous variant of uncertain significance (VUS) (c.11735G>A(p.Cys3912Tyr). The patient's phenotypic presentation was remarkable for hypertrichosis, intellectual disability, intermittent aggressive behavior, developmental delay, failure to thrive, low weight, and the distinct facial features of long eyelashes, telecanthus, corrected strabismus, down-slanting palpebral fissures, and a wide nasal bridge with a broad tip. The importance of this case report stands on the principle of genetic evaluation in patients with ambiguous clinical presentations. In the future, molecular analysis of VUS with pathogenic clinical features can lead to targeted medical management and counseling.