LETTER TO THE EDITOR

Chromosome 16q, Eosinophilia, and Leukemia

Recent reports by Arthur and Bloomfield [1], Le Beau et al. [2], de la Chapelle and Laht inen [3], and Testa et al. [4] have shown that a structural al terat ion of chro- mosome 16q, wi th breakpoint in 16q22, is present in cases of acute non lymphocyt ic leukemia (ANLL) with bone marrow eos inophi l ia and/or morphologica l ly abnormal eosinophi ls . Of a total of 28 reported patients, 5 had a s imple deletion, del(16)(q22) [1], 21 had a pericentr ic inversion of chromosome #16, inv(16)(p13q22) [2, 4], 1 had a rcp(16;16)(p13;q22) [4], i.e., at the same breakpoints as the repor ted inver- sion, and 1 had a complex rearrangement, inc luding inv(16)(p13q22) plus a recip- rocal t ranslocat ion between the inverted chromosome #16 and chromosome #1 [3J. Of the 28 patients, 25 were diagnosed as having acute myelomonocyt ic leukemia M4 and 3 as having acute myeloblast ic leukemia M2. A further pat ient [5] had M4 leukemia and an unbalanced t(3;16)(q24;q22) wi thout apparent eos inophi l abnor- malities. Eosinophi l ia may develop later in this case. These observations have led to the proposal [3, 4] that a break in 16q22 is a crit ical factor in the origin of acute leukemia M4 with eosinophi la .

We have recent ly seen a 63-year-old white male wi th a dysmyelopoie t ic syn- drome (DMS) and bone marrow eosinophi la . At presentat ion, which was for an unrela ted cause, i.e., i schemia of the right leg, he had a per iphera l WBC count of 7800/ram J, 25% of which were eosinophi ls in various stages of maturation. A bone marrow biopsy revealed a cel lular i ty of approximate ly 60%, and in the bone mar- row smear, 70% of the cells were eosinophi ls , most of them in the myelocyte stage of differentiation. Myeloblasts were approximate ly 5%. A cytogenetic analysis of 19

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der 3 3 der16 16

Figure 1 Marrow clone with translocation (3;16)(q21;q22). Complete karyotype: 45,XY,- 5, - 7, -12,t(3;16),+22q-,÷mar. Note that the break- point at 16q22 is associated with eosinophiIia.

Received March 15, 1984; accepted May 30, 1984.

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