Severe atopic dermatitis and growth failure associated with a STAT5B gene mutation in a 7-month-old infant.

STAT5B (signal transducer and activator of transcription 5B) deficiency is a rare autosomal recessive syndrome characterized by severe postnatal growth retardation, atopic dermatitis, and hormonal and immunological abnormalities. We present the case of a 7-month-old male patient with no significant perinatal history who was referred to our clinic for a skin condition that had been present for 5 months, associated with severe growth retardation (low weight for height). After ruling out the most common causes of early-onset atopic dermatitis (such as food allergies, primary immunodeficiencies, and inborn errors of metabolism), genetic testing was performed, leading to a diagnosis of STAT5B deficiency. Our objective is to present a patient with a very rare disease that has a highly characteristic presentation, thereby aiding in early diagnosis.