ADA and severe combined immunodeficiency: Reversion mutations and resultant mosaicism have been reported in Bloom syndrome, X-linked and adenosine deaminase severe combined immunodeficiency (X-SCID and ADA-SCID), Diamond Blackfan anemia (DBA), Wiskott-Aldrich syndrome, epidermolysis bullosa, tyrosinemia, and dyskeratosis congenita (DC) [18–25].