Background. The presented case report demonstrates a rarely described in the literature combination of a sporadic mutation of the TP63 gene with a previously unreported genetic mutation of HG3B, which led to a combined immunodeficiency with multiple congenital malformations. The uniqueness of the case is determined by an atypical combination of genetic disorders and their clinical manifestations. Case Report. A 5-month-old male patient with widespread erythematous-squamous skin lesions on the scalp, face, and extremities, as well as multiple congenital malformations, including cleft palate, hypospadias, and renal abnormalities. The patient was diagnosed with combined immunodeficiency with a T-cell defect, which manifested as recurrent infections. Based on a comprehensive examination, a diagnosis of combined immunodeficiency with a T-cell defect associated with a TP63 gene mutation and an HG3B mutation was made. A comprehensive therapy was carried out, including replacement therapy with immunoglobulins, antibacterial treatment, and the placement of a gastrostomy. As a result of the treatment, the patient’s condition was relatively stabilized. Conclusion. The described case report expands the understanding of the spectrum of clinical manifestations in TP63 gene mutations and demonstrates the need for further study of the role of new genetic mutations in the pathogenesis of immunodeficiency conditions. This case report highlights the importance of a multidisciplinary approach in the diagnosis and treatment of rare genetic diseases.