Malan syndrome (Sotos Syndrome 2, OMIM 614753) is a rare autosomal dominant overgrowth disorder caused by either chromosome 19p13.2/19p13.13 microdeletion or Nuclear Factor 1 X-Type (NFIX) gene haploinsufficiency. Symptoms typically appear in infancy and include dysmorphic features, seizures, and behavioral issues; however, the degree of immune system involvement is not clear. Herein, we are reporting a case of Malan syndrome who presented to the immunology clinic with recurrent bacterial infections, including three episodes of pneumonia confirmed by chest X-ray. Upon further work-up, the patient was found to have hypogammaglobulinemia (IgG 115mg/dL with reference range 445-1,187mg/dL) and poor response to Haemophilus influenzae type B vaccine (<0.11mg/L) and Prevnar vaccine (only 6 out of 12 serotypes were > 1.3 mcg/mL). The frequency of infections decreased dramatically after starting IgG replacement therapy. This case highlights the importance of conducting an immunology work-up in patients with recurrent Pneumonia, especially in patients with chromosomal disorders. Also, Malan syndrome can be associated with significant humoral immunodeficiency (hypogammaglobulinemia), requiring IgG replacement therapy. 

Malan syndrome, NFIX gene haploinsufficiency, Sotos Syndrome 2, Immunodeficiency, Hypogammaglobulinemia, IgG replacement therapy