TRISOMY 8 MOSAICISM: CELL CYCLE KINETICS AND ...

Trisomy 8
INTRODUCTION
Trisomy 8 (T8) is a rare genetic condition in which all of an individual’s cells
have 47 chromosomes including 3 chromosome 8s. T8 occurs in 0.1% of all
recognizable pregnancies and 0.7% of spontaneous abortions (Karadima et al. 1998). T8
is associated with clinical manifestations known as Warkany syndrome (WS). It was
first described in 1962 by Warkany et al. and thought to be due to an extra D group
chromosome. Later cytogenetic evaluation proved WS to be caused by an extra
chromosome 8; confusion of the first diagnosis being a D group chromosome was due to
the extra chromosome as a partial 8; deletion of the short arm. Notable abnormalities of
WS include mild to moderate mental retardation, skeletal anomalies, reduced joint
mobility, renal abnormalities, deep palmar and plantar furrows, long narrow face,
absence of corpus callosum, absence of patellae, and congenital heart defects (Riccardi
1977; Berry et al. 1978; Karadima et al. 1998). T8 has been reported to be incompatible
with life and survival may be possible only in the mosaic form (James and Jacobs 1996;
Karadima et al. 1998; Nicolaidis and Petersen 1998).
Trisomy 8 mosaicism (T8m) is a rare genetic condition in which an individual has
two different cell lines including a normal diploid and a trisomy 8 cell line. Over one
hundred cases of T8 have been reported, the majority of which involve mosaicism
(Kurtyka et al. 1988; Miller et al. 1996; Jordan et al. 1998; Karadima et al. 1998;
Nicolaidis and Petersen 1998). T8m occurs in less than 1 in 25,000 liveborn and is found
to be at a higher frequency (5:1) in males than females (Jordan et al. 1998). This
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