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Lekanne Deprez et a!.
Figure I Basic stem·line brytlt)'pe of meningioma 32 (MN32): 45, XY, -I, 4p+, 22q-, 22q+. Arrows indicJte structurJI
.1bnormalities (Q-b.mding). Insert shows the normal Jnd JberrJnt ,hromosomes from p.lirs 4, 22, Jnd I (R-bJnding).
022515 (results not shown). This indicates that sequences
on 22q distal to 02251 are indeed present on
the 4p + marker. To investigate the possibility of a
balanced translocation t(4;22), we hybridized the
same blots with probes located on 4p16. Probe
D4562, which has been located at position 4p16.2-
16.1, recognizes a 2.4-kb fragment in both placental
and 14G-1O lanes (fig. 3C). This suggests that sequences
up to position 4p16.2 are still retained on
the 4p + marker chromosome. Probe F5.53 (fig. 3D)
recognizes in placental DNA the cognate fragment of
6.5 kb and a cross-hybridizing band at 3.4 kb. Both
bands were mapped on chromosome 4, at positions
4p16.3 (6.5 kb) and 4pI6.1-1S.1 (3.4 kb) (G. J. van
Ommen, personal communication). The 3.4-kb band
is also present in lane 14G-1O. Thus, sequences from
4p16.1-15.1 are retained on the 4p + chromosome, a
finding which confirms the results obtained with probe
D4562. The cognate 6.5-kh band is found in hybrid
6A, suggesting that this part of chromosome 4 has
been translocated to the 22q - marker chromosome.
This conclusion was confirmed by the finding that
probe 045125 (located at 4p16.3) also hybridizes to
DNA from hybrid 6A but not to that from 14G-I0
(result not shown). The same reciprocal marker segregation
pattern was observed with the other hybrid cell
lines.
Thus, t,lken together the hybridization results
strongly suggest that the4p + and 22q - markerchromosomes
are indeed the products of a reciprocal translocation
t(4;22) (p16;qU). Figure 4A shows an outline
of the position of the probes on chromosomes 4
and 22, and in figure 4B their position on the translocation
products is indicated. Hybridizations with 25
other single-copy probes for chromosome 22 (N. A.
van Biezen, unpublished data) showed that all probes
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