Natural history and early diagnosis of LAD-1/variant syndrome

Taco W. Kuijpers, Robin van Bruggen, Nanne Kamerbeek, Anton T. J. Tool, Gonul Hicsonmez, Aytemiz Gurgey, Axel Karow, Arthur J. Verhoeven, Karl Seeger, Ozden Sanal, Charlotte Niemeyer, Dirk Roos

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Abstract

The syndrome of leukocyte adhesion deficiency (LAD) combined with a severe Glanzmann-type bleeding disorder has been recognized as a separate disease entity. The variability in clinical and cell biological terms has remained largely unclear. We present data on 9 cases from 7 unrelated families, with 3 patients being actively followed for more than 12 years. The disease entity, designated LAD-1/variant syndrome, presents early in life and consists of nonpussing infections from bacterial and fungal origin, as well as a severe bleeding tendency. This is compatible with 2 major blood cell types contributing to the clinical symptoms (ie, granulocytes and platelets). In granulocytes of the patients, we found adhesion and chemotaxis defects, as well as a defect in NADPH oxidase activity triggered by unopsonized zymosan. This last test can be used as a screening test for the syndrome. Many proteins and genes involved in adhesion and signaling, including small GTPases such as Rap1 and Rap2 as well as the major Rap activity-regulating molecules, were normally present. Moreover, Rap1 activation was intact in patients' blood cells. Defining the primary defect awaits genetic linkage analysis, which may be greatly helped by a more precise understanding and awareness of the disease combined with the early identification of affected patients
Original languageEnglish
Pages (from-to)3529-3537
JournalBlood
Volume109
Issue number8
DOIs
Publication statusPublished - 2007

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