Rearrangement of Ig heavy chain in HBLD and in HCL-Japanese variant. DNA extracted from mononuclear cells was digested with (A) EcoRI or (B) HindIII restriction enzyme and hybridized to a JH probe. Rearranged bands are indicated by arrows, and germ lines are indicated by dashes. Lane C, normal placenta; lanes 1 through 4, HBLD (cases no. 1 through 4); lane 5, HCL-Japanese variant.