Incontinentia pigmenti with a foreshortened hand: evidence for the significance of NFkappaB in human morphogenesis.

The X-linked disorder incontinentia pigmenti (IP) with its well-defined underlying defect in the NFkappaB essential modulator (NEMO) gene and its variability in patients' phenotypes offers an excellent opportunity for expanding knowledge of the function of the NFkappaB pathway. We report a patient with the classic clinical and histologic characteristics of incontinentia pigmenti in the skin accompanied by foreshortening of the left hand. The occurrence of this limb deformity associated with a reduced expression of NFkappaB confirms the importance of this transcription factor in normal limb morphogenesis and may support its involvement in sonic hedgehog signaling. Further studies in established animal models may help to further define these roles.