5q minus syndrome (MDS)
46,XX,del(5)(q13q33)
Also known as: del(5q), 5q- syndrome
46,XX,del(5)(q13q33) is an interstitial deletion of the long arm of chromosome 5, the defining lesion of the 5q minus subtype of myelodysplastic syndrome. It responds well to lenalidomide and generally has a favorable course.
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What the notation means
The shape of this abnormality
- (5)
- one chromosome, so one group of breakpoints follows.
- (q13q33)
- two bands, written pter to qter, bounding the piece that is lost (an interstitial deletion).
- count · sex chromosomes
- a normal count and the usual female sex chromosomes
- abnormality
- an interstitial DELETION in chromosome 5: the segment between 5q13 and 5q33 is missing
Clinical notes
del(5q), MDS with isolated del(5q)
The one marrow karyotype with its own drug: myelodysplastic syndrome with isolated del(5q) causes anemia with a normal or raised platelet count and hypolobated megakaryocytes, and it responds to lenalidomide. The mechanism is haploinsufficiency, RPS14 for the anemia and CSNK1A1 for the lenalidomide response, with no second hit needed. A co-occurring TP53 mutation predicts lenalidomide failure and transformation, so it is worth looking for at diagnosis. Matched only as an interstitial q-arm deletion, so the constitutional 5q35 deletion of Sotos syndrome never collects this note.