Immunological evaluations revealed a B-cell deficiency (P2: 0.7% CD19 + B cells; P3: 0.55% CD19 + B cells) and hypogammaglobulinemia, including deficiencies in IgM and IgA (P2: IgM 0.02 g/L, IgA 0.01 g/L; P3: IgM 0.03 g/L, IgA 0.01 g/L), while IgG levels were normal (P2: IgG 7.2 g/L, P3: IgG 5.9 g/L) (Table 2). Here, CD79A is linked to B cell deficiency.