Rita Genesio

Altered expression of mitochondrial and extracellular matrix genes in the heart of human fetuses with chromosome 21 trisomy

BackgroundThe Down syndrome phenotype has been attributed to overexpression of chromosome 21 (Hsa21) genes. However, the expression profile of Hsa21 genes in trisomic human subjects as well as their effects on genes located on different chromosomes are largely unknown. Using oligonucleotide microarrays we compared the gene expression profiles of hearts of human fetuses with and without Hsa21 trisomy.ResultsApproximately half of the 15,000 genes examined (87 of the 168 genes on Hsa21) were expressed in the heart at 18–22 weeks of gestation. Hsa21 gene expression was globally upregulated 1.5 fold in trisomic samples. However, not all genes were equally dysregulated and 25 genes were not upregulated at all. Genes located on other chromosomes were also significantly dysregulated. Functional class scoring and gene set enrichment analyses of 473 genes, differentially expressed between trisomic and non-trisomic hearts, revealed downregulation of genes encoding mitochondrial enzymes and upregulation of genes encoding extracellular matrix proteins. There were no significant differences between trisomic fetuses with and without heart defects.ConclusionWe conclude that dosage-dependent upregulation of Hsa21 genes causes dysregulation of the genes responsible for mitochondrial function and for the extracellular matrix organization in the fetal heart of trisomic subjects. These alterations might be harbingers of the heart defects associated with Hsa21 trisomy, which could be based on elusive mechanisms involving genetic variability, environmental factors and/or stochastic events.

Prenatal BACs-on-BeadsTM: the prospective experience of five prenatal diagnosis laboratories

We previously reported on the validation of Prenatal BACs‐on‐BeadsTM on retrospectively selected and prospective prenatal samples. This bead‐based multiplex assay detects chromosome 13, 18, 21 and X/Y aneuploidies and the nine most frequent microdeletion syndromes. We demonstrated that Prenatal BACs‐on‐BeadsTM is a new‐generation, prenatal screening tool. Here, we describe the experience of five European prenatal diagnosis laboratories concerning the ongoing use of Prenatal BACs‐on‐BeadsTM.

Immunoglobulin heavy-chain fluorescence in situ hybridization-chromogenic in situ hybridization DNA probe split signal in the clonality assessment of lymphoproliferative processes on cytological samples.

The human immunoglobulin heavy‐chain (IGH) locus at chromosome 14q32 is frequently involved in different translocations of non‐Hodgkin lymphoma (NHL), and the detection of any breakage involving the IGH locus should identify a B‐cell NHL. The split‐signal IGH fluorescence in situ hybridization‐chromogenic in situ hybridization (FISH‐CISH) DNA probe is a mixture of 2 fluorochrome‐labeled DNAs: a green one that binds the telomeric segment and a red one that binds the centromeric segment, both on the IGH breakpoint. In the current study, the authors tested the capability of the IGH FISH‐CISH DNA probe to detect IGH translocations and diagnose B‐cell lymphoproliferative processes on cytological samples.

A novel CISD2 intragenic deletion, optic neuropathy and platelet aggregation defect in Wolfram syndrome type 2.

BackgroundWolfram Syndrome type 2 (WFS2) is considered a phenotypic and genotypic variant of WFS, whose minimal criteria for diagnosis are diabetes mellitus and optic atrophy. The disease gene for WFS2 is CISD2. The clinical phenotype of WFS2 differs from WFS1 for the absence of diabetes insipidus and psychiatric disorders, and for the presence of bleeding upper intestinal ulcers and defective platelet aggregation. After the first report of consanguineous Jordanian patients, no further cases of WFS2 have been reported worldwide. We describe the first Caucasian patient affected by WFS2.Case presentationThe proband was a 17 year-old girl. She presented diabetes mellitus, optic neuropathy, intestinal ulcers, sensorineural hearing loss, and defective platelet aggregation to ADP. Genetic testing showed a novel homozygous intragenic deletion of CISD2 in the proband. Her brother and parents carried the heterozygous mutation and were apparently healthy, although they showed subclinical defective platelet aggregation. Long runs of homozygosity analysis from SNP-array data did not show any degree of parental relationship, but the microsatellite analysis confirmed the hypothesis of a common ancestor.ConclusionOur patient does not show optic atrophy, one of the main diagnostic criteria for WFS, but optic neuropathy. Since the “asymptomatic” optic atrophy described in Jordanian patients is not completely supported, we could suppose that the ocular pathology in Jordanian patients was probably optic neuropathy and not optic atrophy. Therefore, as optic atrophy is required as main diagnostic criteria of WFS, it might be that the so-called WFS2 could not be a subtype of WFS. In addition, we found an impaired aggregation to ADP and not to collagen as previously reported, thus it is possible that different experimental conditions or inter-patient variability can explain different results in platelet aggregation. Further clinical reports are necessary to better define the clinical spectrum of this syndrome and to re-evaluate its classification.

Partial cerebellar hypoplasia in a patient with Prader-Willi syndrome

UNLABELLED We report a 3-y-old male infant with Prader-Willi syndrome (PWS) caused by a de novo interstitial deletion of 15q11-q13. Additional features included a right cerebellar hemisphere hypoplasia. The extent of deletion was determined by FISH analysis using an SNRPN PW/AS probe that maps in the PWS/AS critical region (CR) and with specific 15q BACs. We unravelled an interstitial 15q11.2-q13.1 deletion spanning about 3 Mb. CONCLUSION To date only a few other PWS patients--including autopsy cases--with CNS structural anomalies have been described. Our case report adds knowledge to the issue of brain involvement in Prader-Willi syndrome. Further MRI studies of PWS patients will be helpful to clarify a correlation between PWS and brain abnormalities.

Clinical description of a patient carrying the smallest reported deletion involving 10p14 region

Haploinsufficiency of a region located distal to 10p14 designated HDR1, is responsible for hypoparathyroidism, sensorineural deafness, and renal anomalies (HDR syndrome). Haploinsufficiency of a more proximal region, located on 10p13‐10p14, designated as DGCR2 is associated with congenital heart defects and thymus hypoplasia/aplasia or T cell defect. We describe a patient showing facial dysmorphisms, delayed psychomotor development and bilateral sensorineural hearing loss and carrying a 10p14 deletion, the smallest deletion found in the literature so far. Our patient, carrying a partial deletion of the DGCR2 region and of the HDR1 region, including the GATA3 gene, showed, unexpectedly, only few of the clinical features of DiGeorge 2 syndrome (psychomotor retardation, palpebral ptosis, epicanthic folds, anteverted nares, cryptorchidism, hand/foot abnormalities) and did not show other typical signs, such as cardiac defect, cleft palate, and abnormal T cell levels. Of the three characteristic features of the HDR syndrome, our patient had only sensorineural deafness. On the basis of the revision of the other cases reported in the literature with a deletion including the 10p14 region, we suggest that GATA3 haploinsufficiency, although not recorded for each patient, is responsible for deafness. The present case shows that even this small 10p deletion is responsible for a specific phenotype. We also underline the importance of CGH‐array, in order to obtain a more precise physical mapping of the 10p deletions and an accurate genotype–phenotype correlation.

Mental Retardation, Congenital Heart Malformation, and Myelodysplasia in a Patient With a Complex Chromosomal Rearrangement Involving the Critical Region 21q22

The region 21q22 is considered crucial for the pathogenesis of both Down syndrome (DS) and the partial monosomy 21q syndrome. Haploinsufficiency of the RUNX‐1 gene, mapping at 21q22 is responsible for a platelet disorder and causes predisposition to myelodysplastic syndrome (MDS). We describe a 3‐year‐old girl with mental retardation, congenital heart malformation, and subtle dysmorphic facial features. The patient developed thrombocytopenia when she was 2 years old. Bone marrow smear led to the diagnosis of myelodysplasia. Prenatal karyotyping had shown chromosome 21 pericentric inversion. Postnatally the array‐CGH revealed duplication at bands 21q11.2–21q21.1 and a simultaneous deletion involving the region 21q22.13–21q22.3. RUNX‐1 mRNA levels analyzed in patients skin fibroblasts were reduced. In this child the monosomy of the region 21q22 likely had the main role in determining the phenotype. Although the RUNX‐1 gene is localized outside the deleted region, we speculate that RUNX‐1 reduced expression, is probably due to the deletion of regulatory factors and caused the hematologic disorder in the patient. The present report underlines also the importance of array‐CGH in characterizing patients with a complex phenotype.

Cytogenetic evaluation of isochromosome 17q in posterior fossa tumors of children and correlation with clinical outcome in medulloblastoma

AbstractBackground.A number of chromosomal abnormalities have been described in the presence of central nervous system tumors; isochromosome 17q, representing a loss of heterozygosity for the short arm of the chromosome 17, is the one most frequently reported in association with medulloblastoma. The purpose of this study was to evaluate the prognostic correlation of this variable, compared with other variables (surgery extent and radiotherapy), with survival. Methods and results.We looked for the presence of i(17q) in 32 children affected by posterior fossa tumors, including 16 medulloblastomas and 2 teratoid/rhabdoid tumors. For our study we used both karyotypic analysis and the fluorescence in situ hybridization (FISH) procedure, both on fresh and on paraffin-embedded tissues. Cytogenetic analysis allowed us to detect a hitherto unreported abnormality in medulloblastoma: ins(1;10)(q31;q23q26). Moreover, 16 of the 32 patients analyzed by FISH were found to be positive for the presence of i(17q): the 2 with teratoid/rhabdoid tumors, 11 of 16 with medulloblastomas, plus 1 with ependymoblastoma and 2 with anaplastic astrocytomas. As far as the outcome of medulloblastoma patients is concerned, we found that 8 out of the 10 children whose tumor had been totally removed had a favorable outcome regardless of the presence of i(17q): 4 were i(17q) positive and 4 i(17q) negative. Conclusions.Although it was impossible to draw any definitive conclusion about detection of i(17q) in central nervous system tumors in infancy, particularly in the case of medulloblastoma, we suggest that this chromosomal abnormality is not an independent prognostic factor, but may be a marker for uncontrolled cell proliferation.

Sonic Hedgehog deletion and distal trisomy 3p in a patient with microphthalmia and microcephaly, lacking cerebral anomalies typical of holoprosencephaly.

About 20% of cases with 7q deletion syndrome is associated with holoprosencephaly (HPE), due to deletion of the Sonic Hedgehog (SHH) gene (mapping to 7q36). The occurrence of severe forms of holoprosencephaly is higher in cases of 7q deletion associated with partial trisomies involving different parts of the genomes than in patients with pure 7q deletion. All cases of 7q deletion associated with 3p duplication reported to date have been associated with severe forms of holoprosencephaly, and a gene(s) on distal 3p has (have) been hypothesized to be responsible for HPE phenotype when in triple dose. Here we describe a patient with unbalanced 3p;7q translocation, showing 7q deletion (including SHH gene) and 3p duplication (complete karyotype was 46,XY,der(7)t(3;7)(p26.3;q36.1)), presenting with a relatively mild phenotype, consisting of microphthalmia and microcephaly, without cerebral anomalies typical of holoprosencephaly. Possible involvement of some genes on 3p in determining such a mild phenotype is discussed.

Metformin restores the mitochondrial network and reverses mitochondrial dysfunction in Down syndrome cells.

Alterations in mitochondrial activity and morphology have been demonstrated in human cells and tissues from individuals with Down syndrome (DS), as well as in DS mouse models. An impaired activity of the transcriptional coactivator PGC-1α/PPARGC1A due to the overexpression of chromosome 21 genes, such as NRIP1/RIP140, has emerged as an underlying cause of mitochondrial dysfunction in DS. We tested the hypothesis that the activation of the PGC-1α pathway might indeed reverse this mitochondrial dysfunction. To this end, we investigated the effects of metformin, a PGC-1α-activating drug, on mitochondrial morphology and function in DS foetal fibroblasts. Metformin induced both the expression of PGC-1α and an augmentation of its activity, as demonstrated by the increased expression of target genes, strongly promoting mitochondrial biogenesis. Furthermore, metformin enhanced oxygen consumption, ATP production, and overall mitochondrial activity. Most interestingly, this treatment reversed the fragmentation of mitochondria observed in DS and induced the formation of a mitochondrial network with a branched and elongated tubular morphology. Concomitantly, cristae remodelling occurred and the alterations observed by electron microscopy were significantly reduced. We finally demonstrated that the expression of genes of the fission/fusion machinery, namely OPA1 and MFN2, was reduced in trisomic cells and increased by metformin treatment. These results indicate that metformin promotes the formation of a mitochondrial network and corrects the mitochondrial dysfunction in DS cells. We speculate that alterations in the mitochondrial dynamics can be relevant in the pathogenesis of DS and that metformin can efficiently counteract these alterations, thus exerting protective effects against DS-associated pathologies.