Full-spine MRI exhibited widening of the distal femoral metaphysis with an "Erlenmeyer flask deformity." Subsequent enzymatic and genetic evaluations for Gaucher disease (GD) confirmed reduced β-glucocerebrosidase (GBA) activity, significantly elevated glucosylsphingosine (Lyso-Gb1) levels, and a homozygous missense mutation in the <i>GBA</i> gene c. The gene discussed is GBA1; the disease is Gaucher disease.