“…3,4,6 To our knowledge, our patient is only the second case reported with skin hyperpigmentation due to LMBRD1 variants. 4 Most of the previously reported patients with Cbl deficiency and unusual pigmentation had a diagnosis of CblJ, an even rarer Cbl disorder due to pathogenic variants within ABCD4 gene. 2 The respective proteins, LMBRD1 (CblF) and ABCD4 (CblJ), colocalize to the lysosome membrane, forming a complex critical to the export of lysosomal Cbl to the cytoplasm.…”