Sg. Vorsanova et al., CYTOGENETIC AND MOLECULAR-CYTOGENETIC INVESTIGATION OF RETT-SYNDROME - ANALYSIS OF 31 CASES, NeuroReport, 8(1), 1996, pp. 187-189
RETT syndrome (RS) is a progressive encephalopathy restricted to the f
emale sex. In the present study we investigated 30 females and one mal
e with RS by cytogenetic and molecular-cytogenetic methods. We failed
to identify any chromosomal rearangements within the female groups and
no correlation between fra(X)(p22) and RS in either the female group
or the male. The boy with RS has karyotype 46,XY/47,XXY with abnormal
cell clone (47,XXY) in 6-12% of his lymphocytes (revealed by fluorecen
ce in situ hybridization analysis (FISH) of interphase cells with chro
mosome X-specific DNA probe). Our results indicated a possible connect
ion between RS and X-chromosome replication disturbance. A late-replic
ating X-chromosome with a specific banding pattern (type 'C') has been
observed in RS patients only. We propose to analyse the X-chromosome
replication pattern as a test for confirmation of RS at preclinical di
agnosis.