B. Panasiuk et al., EARLIER FINISHING OF XP21.2 SUBBAND REPLICATION OF THE INACTIVE X-CHROMOSOME IN RETT-SYNDROME GIRL BUT NOT IN HER 47,XXX MOTHER, Clinical genetics, 52(2), 1997, pp. 120-125
X-inactivation mosaicism has been proposed to explain the origin of Re
tt syndrome. We present the results of the cytogenetic analysis, inclu
ding RBG dynamic replication pattern, in a girl with Rett syndrome. Th
e late replicating X chromosome (LRX) showed the earlier replication o
f subband Xp21.2 in 36% of analysed cells. Unexpectedly the maternal k
aryotype 47,XXX was found. Replication timing of both maternal LRX chr
omosomes was normal. The critical region of Xp essential for RS is pro
posed.