1/4. Occurrence of rett syndrome in boys.The neurologic disorder rett syndrome was originally described exclusively in girls. We present two boys with clinical features of rett syndrome. Other than head circumference deceleration, no longer considered mandatory, patient 1 meets all of the criteria. Using fluorescent in situ hybridization analysis, 97.6% of cells were found to be karyotypically normal (46,XY). No mutation was detected on screening of the coding region of the MECP2 gene. The second patient also has classic features of rett syndrome. However, cytogenetic analysis of peripheral blood revealed a karyotype 47,XXY[23]/46,XY[7] confirming mosaicism for Klinefelter's syndrome. A T158M missense mutation in the methylcytosine-binding domain of the MECP2 gene was identified. A diagnostic bias against the clinical identification of rett syndrome in boys may exist. This presentation of the male phenotype could be more common than it would appear, although boys with MECP2 mutations might also manifest in other ways. rett syndrome remains a clinical diagnosis that should not be dismissed in boys, and thorough evaluation including karyotype and mutation testing is warranted.- - - - - - - - - - ranking = 1keywords = karyotype (Clic here for more details about this article) |
2/4. rett syndrome in a boy with a 47,XXY karyotype confirmed by a rare mutation in the MECP2 gene.rett syndrome (RTT) is an X-linked condition which affects almost exclusively females. Here we report the first case of RTT syndrome in a boy with an XXY chromosomal constitution. mutation analysis of the MECP2 gene in the affected patient revealed a 423 C-->G substitution in exon 4, resulting in a new stop codon (Y141 X). This change was not present in both his parents or in his older sister. Taking into account the incidence of both RTT syndrome as well as of klinefelter syndrome, the probability for the simultaneous occurrence of these two events is very low (about approximately 1 in 10 to 15,000,000 births). However, the recent identification of mutations in the MECP2 gene in affected males indicates that screening of the MECP2 gene should be considered also in males with severe mental retardation (MR) in whom the most common forms of MR have been excluded.- - - - - - - - - - ranking = 2keywords = karyotype (Clic here for more details about this article) |
3/4. Cytogenetic and molecular-cytogenetic studies of rett syndrome (RTT): a retrospective analysis of a Russian cohort of RTT patients (the investigation of 57 girls and three boys).rett syndrome (RTT) is a severe neurodevelopmental disorder with an incidence of 2.5% in mentally retarded girls in russia. We have performed cytogenetic studies of 60 patients (57 girls and three boys) with a clinical picture of RTT, selected according to the criteria for diagnosis of RTT defined by B. Hagberg et al. in 1996. Collection of dna samples and fixed cell suspensions of RTT patients (37 girls and two boys) and their parents (27 patients) was established for molecular studies, for example analysis of MECP2 mutations in a Russian cohort of RTT patients. Among 60 patients 57 girls with a clinical picture of RTT had normal female karyotype (46,XX), one boy had normal male karyotype in peripheral lymphocytes (46,XY) and two boys had a mosaic form of Kleinfelter's syndrome (47,XXY/46,XY) in peripheral lymphocytes or muscle cells (with MeCP2 mutation R270X). Twenty-four mothers and parents of RTT girls had normal karyotype, two mothers had mosaic forms of turner syndrome (45,X/46,XX) and one had mosaic karyotype (47,XX, mar/48,XXX, mar). We analyzed chromosome X in lymphocytes of 57 affected girls with a clinical picture of RTT using the 5-bromo-2'-deoxyuridine Giemsa staining technique. A specific type of inactive chromosome X (so-called type 'C') with unusual staining of chromatin in the long arm of chromosome X was found in 55 (from 57) girls with RTT. This technique was positively used for presymptomatic diagnosis of RTT in five girls in earlier stages of the disease. We believe that the phenomenon of altered chromatin conformation in inactive chromosome X could be used as a laboratory test for preclinical diagnosis of the RTT.- - - - - - - - - - ranking = 2keywords = karyotype (Clic here for more details about this article) |
4/4. Somatic mosaicism for a MECP2 mutation associated with classic rett syndrome in a boy.rett syndrome is a severe neurodevelopmental disorder that arises from mutations in the X-linked MECP2 gene. It is almost exclusively seen in girls due to the predominant occurrence of the mutations on the paternal X-chromosome, and also the early postnatal lethal effect of the disease causing mutations in hemizygous boys. We identified a boy with features of classic rett syndrome who is mosaic for the truncating MECP2 mutation R270X. Chromosome analysis showed normal karyotype. These results indicate that a MECP2 mutation associated with rett syndrome in females could lead to a similar phenotype in males as a result of somatic mosaicism.- - - - - - - - - - ranking = 0.5keywords = karyotype (Clic here for more details about this article) |