Daniela Giardino

13q Deletion and central nervous system anomalies: further insights from karyotype–phenotype analyses of 14 patients

Background: Chromosome 13q deletion is associated with varying phenotypes, which seem to depend on the location of the deleted segment. Although various attempts have been made to link the 13q deletion intervals to distinct phenotypes, there is still no acknowledged consensus correlation between the monosomy of distinct 13q regions and specific clinical features. Methods: 14 Italian patients carrying partial de novo 13q deletions were studied. Molecular–cytogenetic characterisation was carried out by means of array-comparative genomic hybridisation (array-CGH) or fluorescent in situ hybridisation (FISH). Results: Our 14 patients showed mental retardation ranging from profound–severe to moderate–mild: eight had central nervous system (CNS) anomalies, including neural tube defects (NTDs), six had eye abnormalities, nine had facial dysmorphisms and 10 had hand or feet anomalies. The size of the deleted regions varied from 4.2 to 75.7 Mb. Conclusion: This study is the first systematic molecular characterisation of de novo 13q deletions, and offers a karyotype–phenotype correlation based on detailed clinical studies and molecular determinations of the deleted regions. Analyses confirm that patients lacking the 13q32 band are the most seriously affected, and critical intervals have been preliminarily assigned for CNS malformations. Dose-sensitive genes proximal to q33.2 may be involved in NTDs. The minimal deletion interval associated with the Dandy–Walker malformation (DWM) was narrowed to the 13q32.2–33.2 region, in which the ZIC2 and ZIC5 genes proposed as underlying various CNS malformations are mapped.

The Italian National Survey for Prader-Willi syndrome: an epidemiologic study.

Twenty‐five medical centers and the Prader–Willi Syndrome (PWS) Association collaborated on a study which attempted to identify all people with genetically confirmed diagnosis of PWS living in Italy. Investigators of the participating centers contacted PWS subjects and/or their family, filled in a specially developed form with the required data and forwarded this information by email. The study identified 425 subjects (209 males and 216 females, between the ages of 0.4–46.7). Two hundred thirty‐eight patients had del15, 104 had UPD15, 4 demonstrated a translocation affecting chromosome 15 and 79 showed a positive methylation test. There were fewer subjects found over the age of 35, probably due to the low rate of identification of older PWS patients as well as the high mortality rate. There were a greater number of male children and adolescents with PWS whilst, amongst adults, there were more females. As expected, the majority of subjects with PWS were obese, especially in adult life. Nevertheless, it is noteworthy that 26% of patients aged between 6 and 17 were normal weight. A total of 212 subjects had received GH treatment, of which 141 were still receiving therapy, while the remaining 71 had stopped. In children and adolescents (233 cases), 89 subjects had never undergone GH therapy. Eighteen PWS patients had died in the past 20 years. Obesity‐related cardiovascular and respiratory diseases were the cause of death, both during childhood and after 18 years of age. Three children died suddenly whilst undergoing GH therapy. Respiratory infection and cardiac illness were the causes of death in two cases. There was no definitive cause of death found in the third case. Overall, there was no increase in number of deaths during GH treatment, suggesting that GH administration in patients with PWS, as a group, does not increase the risk of death.

De novo balanced chromosome rearrangements in prenatal diagnosis

We surveyed the datasheets of 29 laboratories concerning prenatal diagnosis of de novo apparently balanced chromosome rearrangements to assess the involvement of specific chromosomes, the breakpoints distribution and the impact on the pregnancy outcome.

Non-random trisomies of chromosomes 5, 8 and 12 in the prolactinoma sub-type of pituitary adenomas: Conventional cytogenetics and interphase fish study

Specimens from 53 pituitary adenomas (PAs), including 17 NFPA, 16 PRL‐, 9 ACTH‐, 9 GH‐ and 2 TSH‐secreting tumors, underwent cytogenetic analysis by the direct and short‐term culture methods. Only 8 tumors (15%) appeared to have an abnormal karyotype. To increase the resolution of cytogenetic analysis, direct preparations from 31 PAs were investigated by interphase FISH with probes specific for chromosomes 5, 8, 12 and X, for which gain in pituitary tumors has been reported. Of these 31 PAs, 17 (54.8%) had an abnormal dosage of one or more of the 4 chromosomes tested. Separate or combined trisomies of chromosomes 5, 8 and 12 were found in 10/10 prolactinomas and in 4/9 NFPA, whereas the combined loss of chromosomes 5 and 8 was observed in 1/6 ACTH‐ and 1/6 GH‐secreting PAs. Present and earlier data on 23 PAs showed that tumors with the highest frequency of abnormal karyotypes revealed by cytogenetics and/or interphase FISH were PRL (78%), followed by NFPA (26%) and GH (18%). Recurrent structural rearrangements affecting chromosomes 1, 3 and 12 were also identified in prolactinomas, which therefore appear to be the only pituitary adenoma sub‐type with a defined trend of tumor‐specific chromosomal changes. Cytogenetic and FISH analyses of different pituitary tumor sub‐types indicate that they may harbour genetically distinct lesions. Int. J. Cancer 86:344–350, 2000.

Cytogenetic study of pituitary adenomas

We report the results of cytogenetic studies on 23 pituitary adenoma specimens, using both the direct and short-term tissue culture methods. The direct method was applied to all of the specimens and allowed a karyotype to be identified in 15 of the processed samples (65%). Four tumors were shown to have a hypotriploid chromosomal constitution, two of which also presented structural clonal rearrangements: an isochromosome 1q,i(1)(q10) and a der(1)t(1;3)(p22;q21) were observed in two PRL-secreting adenomas, one of which also had a telomeric association involving the short arms of chromosomes 14 and 19. Telomeric associations of the long arms of chromosomes 11, 19, and 22 were observed in a near-diploid, non-secreting tumor showing monosomy 13. One other adenoma showed trisomies 8 and 12, a finding that was confirmed by means of the FISH analysis of chromosome 8 and 12 centromeric probes in the more than 300 scored nuclei. An apparently normal chromosome constitution was observed in the remaining nine cases. Short-term cultures were set up in 21 of the 23 samples, allowing us to obtain a karyotype in 18 specimens (85%). The six tumors that could not be analyzed using the direct method showed a normal karyotype. A diploid chromosome constitution was observed in the four tumors shown to be hypotriploid by the direct method as well as in the tumor with monosomy 13. The trisomies 8 and 12 identified by the direct method in one tumor were still observed, but a clone with a normal karyotype was also found. To the best of our knowledge, this is the only report of the results of cytogenetic studies on pituitary adenomas performed using both direct preparation and short-term culture.

Genotype–phenotype correlations in a new case of 8p23.1 deletion and review of the literature

We describe a 6-year-old boy carrying a de novo 5 Mb interstitial deletion of chromosome 8p23.1 identified by means of oligonucleotide array comparative genomic hybridisation (array CGH), who showed the typical signs of 8p23.1 deletion syndrome, including congenital heart defects, microcephaly, psychomotor delay and behavioural problems. In order to estimate the role of suggested candidate genes, we compared the deletion of our patient with other previously reported and molecularly characterised deletions that have been re-evaluated on the basis of the current genetic map data. The inclusion of TNKS gene in the deletion interval without any phenotypical signs of Cornelia de Lange syndrome (CdLS) invalidates TNKS as a plausible candidate gene for the syndrome itself.

Angelman's Syndrome in the First Year of Life

Angelman Syndrome usually has been considered to be rare and sporadic. However, recent reports suggest a sibling recurrence risk of just under 25 per cent, so early diagnosis is very important. The authors report Angelman Syndrome in a child of seven months. The early features of this Syndrome (jerky movements, EEG characteristics, chromosomal abnormalities in half the cases) should make it possible to diagnose or suspect the Syndrome in the first year of life.

FISH characterisation of an identical (16)(p11.2p12.2) tandem duplication in two unrelated patients with autistic behaviour

Partial trisomy 16p is a rare chromosomal anomaly in newborns: of the fewer than 30 carrier patients so far reported, most were born to parents with a balanced translocation involving the p arm of chromosome 16.1 Pure partial trisomy 16p has been reported in seven patients,2–6 three of whom (all showing behavioural problems with autistic traits) carried a tandem duplication of the (16)(p11.2–p12) region4,6; minor dysmorphisms were reported in only one patient.4 Linkage studies indicated chromosome 16p as a major location for autism susceptibility genes,7 while association was reported between autistic traits and attention deficit or hyperactivity disorders mapping to the 16p13 band.8 In addition TSC2, one of the genes responsible for tuberous sclerosis, a syndrome often associated with autistic traits, maps to the same cytogenetic band.9 We report the clinical phenotype and refined molecular cytogenetic characterisation of a patient carrying a (16)(p11.2p12.2) duplication. By extending the FISH analysis to a previously described patient with an apparently similar chromosomal rearrangement,6 we found that low copy repeats map to the 16p11.2 and 16p12.2 duplication endpoints, suggesting non-allelic homologous recombination as the pathogenetic mechanism. This finding is consistent with the non-random occurrence of the observed chromosomal rearrangement and the high frequency of segmental duplications identified throughout chromosome 16.10–12 We also inferred from genotype-phenotype correlation studies that genes involved in autism susceptibility are located within the duplicated region. Patient 1 is a 25 year old man, the first son of unrelated parents. At the time of his birth, his mother was aged 30 and his father 29 years. He was born at term with a weight of 2.550 kg (3rd centile). The father suffered from alcohol misuse and left the family when the patient was 12 years old. Because of …

Disruption of friend of GATA 2 gene (FOG-2) by a de novo t(8;10) chromosomal translocation is associated with heart defects and gonadal dysgenesis

FOG‐2 (Friend of GATA 2) is a transcriptional cofactor able to differentially regulate the expression of GATA‐target genes in different promoter contexts. Mouse models evidenced that FOG‐2 plays a role in congenital heart disease and normal testis development. In human, while FOG‐2 mutations have been identified in sporadic cases of tetralogy of Fallot, no mutations are described to be associated with impaired gonadal function. We here describe a young boy with a balanced t(8;10)(q23.1;q21.1) translocation who was born with congenital secundum‐type atrial septal defect and gonadal dysgenesis. Fluorescence in situ hybridization mapped the chromosome 8 translocation breakpoint (bkp) to within the IVS4 of the FOG‐2 gene, whereas the chromosome 10 bkp was found to lie in a desert gene region. Quantitative analysis of FOG‐2 expression revealed the presence of a truncated transcript but there was no detectable change in the expression of the genes flanking the 10q bkp, thus making it possible to assign the observed clinical phenotype to altered FOG‐2 expression. Genetic and clinical analyses provide insights into the signaling pathways by which FOG‐2 affects not only cardiac development but also gonadal function and its preservation.

Biocompatible fluorescent nanoparticles for in vivo stem cell tracking

Efficient application of stem cells to the treatment of neurodegenerative diseases requires safe cell tracking to follow stem cell fate over time in the host environment after transplantation. In this work, for the first time, fluorescent and biocompatible methyl methacrylate (MMA)-based nanoparticles (fluoNPs) were synthesized through a free-radical co-polymerization process with a fluorescent macromonomer obtained by linking Rhodamine B and hydroxyethyl methacrylate. We demonstrate that the fluoNPs produced by polymerization of MMA-Rhodamine complexes (1) were efficient for the labeling and tracking of multipotent human amniotic fluid cells (hAFCs); (2) did not alter the main biological features of hAFCs (such as viability, cell growth and metabolic activity); (3) enabled us to determine the longitudinal bio-distribution of hAFCs in different brain areas after graft in the brain ventricles of healthy mice by a direct fluorescence-based technique. The reliability of our approach was furthermore confirmed by magnetic resonance imaging analyses, carried out by incubating hAFCs with both superparamagnetic iron oxide nanoparticles and fluoNPs. Our data suggest that these finely tunable and biocompatible fluoNPs can be exploited for the longitudinal tracking of stem cells.