Biology Reference
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syndrome type 1 (WS1), seen in Figure 5.8A. This child represented a new
mutation in his family and, significantly, also had a
de novo
chromosome
inversion involving the distal portion of the q arm of chromosome 2 includ-
ing bands 2q35 and 2q37.3 (Fig. 5.8B). Prior to this report,WS1 had not been
assigned to a chromosomal location. Earlier reports of possible linkage to
the ABO blood group at 9q34 (Simpson et al. 1974) could not be confirmed.
Using the genomic landmarks provided by inv(2)(q35q37.3), Foy et al.
(1990) established genetic linkage of WS1 to distal chromosome 2q, and
FIGURE 5.8. De novo chromosome rearrangement that was used to facilitate
mapping the locus for Waardenburg syndrome type 1. (A) Japanese boy with
WS1 in which a
de novo
chromosome 2 inversion was observed (From Ishikiriyama
et al. 1989, Waardenburg syndrome type I in a child with
de novo
inversion (2)
(q35q37.3), American Journal of Medical Genetics 33:505-7, Copyright 1989 John
Wiley & Sons, Inc. Reprinted by permission of Wiley-Liss, Inc., a subsidiary of John
Wiley & Sons, Inc.). Notice the pigmentary anomalies of the skin and heterochro-
mia irides. (B) Ideogram of chromosome 2, showing the inversion seen in this child
and the position of the WS1 gene,
PAX3
, at the q35 inversion breakpoint.
