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Mosaic Intrachromosomal Triplication of (12)(p11.2p13) in a Patient with Pallister-Killian SyndromePallister-Killian syndrome (PKS) is a rare genetic disorder usually characterized by mosaic tetrasomy of isochromosome 12p detected in cultured fibroblast cells. We describe here a patient with PKS and intrachromosomal triplication of the short arm of chromosome 12. Her karyo-type was mos 46, XX, inv trp(12)(p11.2p13)[34]/46, XX[16] de novoby conventional cytogenetics and fluorescent in situhybridization (FISH) analysis. However, this chromosomal abnormality was not detected from the patient's cultured blood lymphocytes. We report here the third patient with intrachromosomal triplication on the short arm of chromosome 12, presenting a PKS phenotype.

Turner Syndrome with Isochromosome Xq and Familial Reciprocal Translocation t(4;16)(p15.2;p13.1)We present here a 16-year-old Turner syndrome patient with a complex karyotype that includes a maternally-inherited balanced translocation between chromosomes 4 and 16 and mosaicism of the isochromosome Xq10. Her karyotype was 45, X, t(4;16) (p15.2;p13.1)[9]/46, X, i(X) (q10),t(4;16)(p15.2;p13.1) [91]. The karyotype of her father was normal, whereas that of her mother had the same balanced translocation and numerical abnormalities of chromosome X and was designated as 45, X, t(4;16)(p15.2;p13.1) [2]/ 46, XX, t(4;16)(p15.2;p13.1)[93]/47, XXX, t(4;16) (p15.2; p13.1)[5]. The two siblings of the patient also had the same reciprocal translocation. We consider this to be the first such patient with an inherited reciprocal translocation and structural abnormality of the X chromosome (isochromosome Xq).

Aplasia Ras Homologous Member I Gene and Development of Glial TumorsThe ARHI (aplasia Ras homologue member I, also known as DIRAS3) gene shows 60.0% sequence homology to the Ras proto-oncogene and was the first mater-nally-imprinted tumor suppressor gene identified in the Ras family. It is constitutively expressed from the paternal allele in normal breast, ovary, heart, liver, pancreas, thyroid and brain tissues, and is lost or markedly down-regulated primarily in breast, ovarian, pancreas and thyroid tumor tissues. We have investigated the expression, LOH (loss of heterozygosity) and methylation status of this gene in glial tumors and peripheral blood samples of 21 patients, and in seven normal brain tissue samples. Gene expression by real time reverse transcriptase polymerase chain reaction (RTPCR) was found to be increased in 14 and decreased in seven of the 21 tumors. The LOH was detected by fragment analysis, using five labeled polymorphic markers specific for the 1p31 region, in two of the tumors. Methylation status of the CpG island I, II and III was evaluated using COBRA (combined bisulfite restriction analysis) and RFLP (restriction fragment length polymorphism) in 21 tumors and also a hypermethylated healthy volunteer as a positive control, revealed that only two tumors had hypermethylation in CpG island I (of which one also had LOH). These results suggest that LOH and hypermethylation may be one mechanism of silencing the ARHI gene expression and development of glial tumor development.

Cytogenetic, FISH, and molecular results of 20 cases with de novo tandem duplications of 18 different autosomal chromosome segments are reported. There were 12 cases with direct duplications, three cases with inverted duplications, and five in whom determination of direction was not possible. In seven cases a rearrangement between non-sister chromatids (N-SCR) was found, whereas in the remaining 13 cases sister chromatids (SCR) were involved. Paternal and maternal origin (7:7) was found almost equally in cases with SCR (3:4) and N-SCR (4:3). In the cases with proven inversion, there was maternal and paternal origin in one case each. Twenty three out of 43 cytogenetically determined breakpoints correlated with common or rare fragile sites. In five cases, including all those with proven inverse orientation, all breakpoints corresponded to common or rare fragile sites. In at least two cases, one with an interstitial duplication (dup(19)(q11q13)) and one with a terminal duplication (dup(8) (p10p23)), concomitant deletions (del(8) (p23p23.3) and del(19)(q13q13)) were found.