Using array comparative genome hybridisation (CGH) 41 de novo reciprocal translocations and 18 de novo complex chromosome rearrangements (CCRs) were screened. All cases had been interpreted as ''balanced'' by conventional cytogenetics. In all, 27 cases of reciprocal translocations were detected in patients with an abnormal phenotype, and after array CGH analysis, 11 were found to be unbalanced. Thus 40% (11 of 27) of patients with a ''chromosomal phenotype'' and an apparently balanced translocation were in fact unbalanced, and 18% (5 of 27) of the reciprocal translocations were instead complex rearrangements with .3 breakpoints. Fourteen fetuses with de novo, apparently balanced translocations, all but two with normal ultrasound findings, were also analysed and all were found to be normal using array CGH. Thirteen CCRs were detected in patients with abnormal phenotypes, two in women who had experienced repeated spontaneous abortions and three in fetuses. Sixteen patients were found to have unbalanced mutations, with up to 4 deletions. These results suggest that genome-wide array CGH may be advisable in all carriers of ''balanced'' CCRs. The parental origin of the deletions was investigated in 5 reciprocal translocations and 11 CCRs; all were found to be paternal. Using customised platforms in seven cases of CCRs, the deletion breakpoints were narrowed down to regions of a few hundred base pairs in length. No susceptibility motifs were associated with the imbalances. These results show that the phenotypic abnormalities of apparently balanced de novo CCRs are mainly due to cryptic deletions and that spermatogenesis is more prone to generate multiple chaotic chromosome imbalances and reciprocal translocations than oogenesis.

Beyond the disorders recognized as mitochondrial diseases, abnormalities in function and/or ultrastructure of mitochondria have been reported in several unrelated pathologies. These encompass ageing, malformations, and a number of genetic or acquired diseases, as diabetes and cardiologic, haematologic, organ-specific (e.g., eye or liver), neurologic and psychiatric, autoimmune, and dermatologic disorders. The mechanistic grounds for mitochondrial dysfunction (MDF) along with the occurrence of oxidative stress (OS) have been investigated within the pathogenesis of individual disorders or in groups of interrelated disorders. We attempt to review broad-ranging pathologies that involve mitochondrial-specific deficiencies or rely on cytosol-derived prooxidant states or on autoimmune-induced mitochondrial damage. The established knowledge in these subjects warrants studies aimed at elucidating several open questions that are highlighted in the present review. The relevance of OS and MDF in different pathologies may establish the grounds for chemoprevention trials aimed at compensating OS/MDF by means of antioxidants and mitochondrial nutrients.

BackgroundKabuki syndrome (Niikawa-Kuroki syndrome) is a rare, multiple congenital anomalies/mental retardation syndrome characterized by a peculiar face, short stature, skeletal, visceral and dermatoglyphic abnormalities, cardiac anomalies, and immunological defects. Recently mutations in the histone methyl transferase MLL2 gene have been identified as its underlying cause.MethodsGenomic DNAs were extracted from 62 index patients clinically diagnosed as affected by Kabuki syndrome. Sanger sequencing was performed to analyze the whole coding region of the MLL2 gene including intron-exon junctions. The putative causal and possible functional effect of each nucleotide variant identified was estimated by in silico prediction tools.ResultsWe identified 45 patients with MLL2 nucleotide variants. 38 out of the 42 variants were never described before. Consistently with previous reports, the majority are nonsense or frameshift mutations predicted to generate a truncated polypeptide. We also identified 3 indel, 7 missense and 3 splice site.ConclusionsThis study emphasizes the relevance of mutational screening of the MLL2 gene among patients diagnosed with Kabuki syndrome. The identification of a large spectrum of MLL2 mutations possibly offers the opportunity to improve the actual knowledge on the clinical basis of this multiple congenital anomalies/mental retardation syndrome, design functional studies to understand the molecular mechanisms underlying this disease, establish genotype-phenotype correlations and improve clinical management.

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The present study was aimed at verifying the occurrence, if any, of in vivo oxidative DNA damage in FA homozygotes, their parents and siblings. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) was measured, by HPLC/EC, in DNA from circulating blood leucocytes from FA homozygotes and their relatives and compared with a group of paediatric and adult healthy subjects. The population studied consisted of: (i) 15 FA homozygotes; (ii) 24 FA heterozygotes; (iii) 11 siblings. The 8-OHdG level in FA homozygotes was significantly higher with respect to age-matched controls, with a mean level of 33.3 +/- 6.8 (mean +/- SE) and 3.9 +/- 0.26 8-OHdG/10(5) dG respectively. The FA parents (heterozygotes) also displayed higher 8-OHdG levels relative to controls. The release of hydroxyl (.OH) and .OH-like radicals from leucocytes was determined by luminol-dependent chemiluminescence (LDCL) in a subgroup of FA homo- and heterozygotes, showing a very large in vivo formation of non-superoxide radicals. Chromosomal instability was also measured in the FA population. When relating either 8-OHdG or LDCL levels to spontaneous or diepoxybutane-induced chromosomal instability (S-CI and DEB-CI respectively), a significant correlation was observed between the 8-OHdG, LDCL and S-CI data. Within families a positive association was found between 8-OHdG levels in homozygotes and their related heterozygotes, suggesting segregation of the genetic defect(s) underlying the abnormal oxidative metabolism. The present study provides evidence for an in vivo pro-oxidant state in FA, in terms of excess formation of .OH and .OH-like radicals, and of DNA hydroxyl adducts. This finding appears to be shared by homozygotes and, to a lesser extent, by heterozygotes.

Fanconi anaemia (FA) definitions Fanconi anaemia (FA) is a genetic disease associated with progressive haematopoietic impairment, chromosomal instability, and poor prognosis related to pancytopenia and to excess risk of malig-nancies, mainly non-lymphocytic leukaemia (1, 2). Apart from its mostly fatal haematologic and oncologic features, FA is also characterised by a multi-faceted clinical pattern including a typical set of malformations, some endocrine abnormalities (mainly type II diabetes mellitus), and altered skin pigmentation (e.g. cafe´-cafe´-au-lait spots) (3, 4). Inherited as an autosomal recessive disorder (with the exception of FA gene B, FANCB, with X-linked localisation), FA comprises a total of at least 11 complementation groups, and most of the FA gene-encoded proteins have been reported to cooperate in a common pathway (5-7). Diagnosis and toxicity mechanisms of FA-related xenobiotics Diagnosis is performed by testing FA cell sensitivity to two clastogens, either diepoxybutane (DEB) or mitomycin C (MMC) (2) that cause higher-than-normal chromosomal breakages in FA cells. The sensitivity to DEB and MMC also relates to the current attribution of FA phenotype, commonly referred to as Ôcrosslinker sensitivityÕ (2, 5-6). This term relates to the formation of DNA Pagano G, Degan P, d'Ischia M, Kelly FJ, Nobili B, Pallardo´FVPallardo´FV, Youssoufian H, Zatterale A. Oxidative stress as a multiple effector in Fanconi anaemia clinical phenotype. Eur J Haematol 2005: 75: 93-100. Ó Blackwell Munksgaard 2005. Abstract: Fanconi anaemia (FA) is a genetic disease characterised by bone marrow failure with excess risk of myelogenous leukaemia and solid tumours. A widely accepted notion in FA research invokes a deficiency of response to DNA damage as the fundamental basis of the Ôcrosslinker sensitivityÕ observed in this disorder. However, such an isolated defect cannot readily account for the full cellular and clinical phenotype, which includes a number of other abnormalities, such as malformations, endocrinopathies, and typical skin spots. An extensive body of evidence pointing toward an involvement of oxidative stress in the FA phenotype includes the following: (i) In vitro and ex vivo abnormalities in a number of redox status endpoints; (ii) the functions of several FA proteins in protecting cells from oxidative stress; (iii) redox-related toxicity mechanisms of the xenobiotics evoking excess toxicity in FA cells. The clinical features in FA and the in vivo abnormalities of redox parameters are here reconsidered in view of the pleiotropic clinical phenotype and known biochemical and molecular links to an in vivo prooxidant state, which causes oxidative damage to biomolecules, resulting in an excessive number of acquired abnormalities that may overwhelm the cellular repair capacity rather than a primary deficiency in DNA repair. FA may thus represent a unique model disease in testing the integration between the acquisition of macromolecular damage as a result of oxidative stress and the ability of the mammalian...

Oxidative stress has been associated with Down syndrome (DS) and with its major phenotypic features, such as early ageing. In order to evaluate an in vivo pro-oxidant state, the following analytes were measured in a group of DS patients aged 2 months to 57 years: (a) leukocyte 8-hydroxy-2'-deoxyguanosine (8-OHdG); (b) blood glutathione; (c) plasma levels of: glyoxal (Glx) and methylglyoxal (MGlx); some antioxidants (uric acid, UA, ascorbic acid, AA and Vitamin E), and xanthine oxidase (XO) activity. A significant 1.5-fold increase in 8-OHdG levels was observed in 28 DS patients vs. 63 controls, with a sharper increase in DS patients aged up to 30 years. The GSSG:GSH x 100 ratio was significantly higher in young DS patients (< 15 years), in contrast to DS patients aged >or=15 years that showed a significant decrease in the GSSG:GSH x 100 ratio ratio vs. controls of the respective age groups. Plasma Glx levels were significantly higher in young DS patients, whereas no significant difference was detected in DS patients aged >or=15 years. Unlike Glx, the plasma levels of MGlx were found to be significantly lower in DS patients vs. controls. A significant increase was observed in plasma levels of UA in DS patients that could be related to an increased plasma XO activity in DS patients. The plasma concentrations of AA were also increased in young (< 15 years) DS patients, but not in older patients vs. controls in the same age range. The levels of Vitamin E in DS patients did not differ from the values determined in control donors. The evidence for a multiple pro-oxidant state in young DS patients supports the role of oxidative stress in DS phenotype, with relevant distinctions according to patients' ages.

The trisomy 8 found in malignancies may derive from a constitutional trisomy 8 mosaicism (CT8M), and in these cases the trisomy itself may be regarded as the first mutation in a multistep carcinogenetic process. To assess the frequency of CT8M in hematological dysplastic and neoplastic disorders with trisomy 8, an informative sample of 14 patients was collected. The data ascertained included chromosome analyses of fibroblast cultures and of PHA-stimulated blood cultures in patients with normal blood differential count, as well as possible CT8M clinical signs. One patient showed trisomy 8 in all cell types analyzed and undoubtedly has a CT8M; a second patient consistently showed trisomy 8 in PHA-stimulated blood cultures when no immature myeloid cells were present in blood and should be considered as having CT8M; a third patient, with Philadelphia-positive chronic myelocytic leukemia, was more difficult to interpret, but the possibility that she had CT8M is likely. A few clinical signs of CT8M were also present in these three patients. Our data indicate that the frequency of CT8M in hematological dysplastic and neoplastic disorders with trisomy 8 is approximately 15-20%.