No major defect detected in the gene of familial hypo-retinol-binding proteinemia

Retinol-binding protein (RBP), a plasma protein with a molecular weight of 21,000 daltons, binds to retinol with a 1:1 molar ratio and transports it to the peripheral tissues. Familial hypo-retinol-binding proteinemia (hypo-RBPnemia) was detected in a 2-year-old girl who developed keratomalacia, and in her mother and sister. They persistently showed half the normal levels of RBP and retinol. Restriction fragments of leukocyte DNA, created by digestion with BamHI, EcoRI and PstI when human RBP complementary DNA was used as a probe, showed the same patterns in both the affected and unaffected family members. These results indicate that familial hypo-RBPnemia could be attributed to such minor changes as point mutations, rather than large deletion or insertion in the RBP gene.