Semi-quantitative grading of haematoxylin and eosin-stained mouse spleen sections. 0=not present; 1=minimal; 2=mild; 3=moderate; 4=marked; P=present and not gradable. The spleens were from four WT and four D427N PKCβ hets at 18 months old (Hets 1–3 had splenomegaly and a phenotype by flow cytometry, whereas Het 4 did not; see spleen images in Figure 4). Hom 1 was culled sick at eight months and had splenomegaly. The gene discussed is PRKCB; the disease is Splenomegaly.