In Portuguese Water Dogs, a genetic variant in the DNAJC21 gene has been identified that causes microphthalmia with defects of the hematopoietic system (hematopoietic defects). Affected dogs show a unilateral or bilateral reduction of the eyes to less than 50% of the normal size. In addition, other ocular defects such as cataracts, corneal dystrophy, reduction or absence of the crystalline lens (microphakia/aphakia), glaucoma, retinal lesions and persistent pupillary membranes can be observed in some dogs. In addition, changes in tooth enamel, growth retardation and blood formation disorders such as a reduced number of platelets (thrombocytopenia) and red blood cells (anemia) may occur. With increasing age, the number of red blood cells and the hematocrit can improve, while the platelet count remains low.