Tissue-specific differences in the proportion of mosaic large NF1 deletions are suggestive of a selective growth advantage of hematopoietic del(+/−) stem cells
✍ Scribed by Angelika C. Roehl; Tanja Mussotter; David N. Cooper; Lan Kluwe; Katharina Wimmer; Josef Högel; Marion Zetzmann; Julia Vogt; Victor-Felix Mautner; Hildegard Kehrer-Sawatzki
- Publisher
- John Wiley and Sons
- Year
- 2012
- Tongue
- English
- Weight
- 331 KB
- Volume
- 33
- Category
- Article
- ISSN
- 1059-7794
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✦ Synopsis
Type-2 NF1 deletions spanning 1.2 Mb are frequently of postzygotic origin and hence tend to be associated with mosaicism for normal cells and those harboring the deletion (del(+/-) cells). Eleven patients with mosaic type-2 deletions were investigated by FISH and high proportions (94-99%) of del(+/-) cells were detected both in whole blood and in isolated CD3+, CD14+, CD15+, and CD19+ leukocytes. Significantly lower proportions of del(+/-) cells (24-82%) were however noted in urinederived epithelial cells. A patient harboring an atypical large NF1 deletion with nonrecurrent breakpoints was also found to have a much higher proportion of del(+/-) cells in blood (96%) than in urine (51%). The tissuespecific differences in the proportions of del(+/-) cells as well as the X chromosome inactivation (XCI) patterns observed in these mosaic patients suggest that the majority of the deletions had occurred before or during the preimplantation blastocyst stage before the onset of XCI. We postulate that hematopoietic del(+/-) stem cells present at an early developmental stage are characterized by a selective growth advantage over normal cells lacking the deletion, leading to a high proportion of del(+/-) cells in peripheral blood from the affected patients.