[Show abstract][Hide abstract] ABSTRACT: Duplications encompassing the MECP2 gene on the Xq28 region have been described in male patients with moderate to severe mental retardation, absent speech, neonatal hypotonia, progressive spasticity and/or ataxia, recurrent severe respiratory infections, gastrointestinal problems, mild facial dysmorphisms (midface hypoplasia, depressed nasal bridge, large ears) and epilepsy. Epilepsy can occur in >50% of cases, but the types of seizures and the electroclinical findings in affected male individuals have been poorly investigated up to the present. Herein we describe eight patients with MECP2 duplication syndrome and a specific clinical and electroencephalographic pattern.
Array CGH of genomic DNA from the probands was performed, and an Xq28 duplication ranging from 209 kb to 6.36 Mb was found in each patient. Electroencephalography studies and clinical and seizure features of all the patients were analyzed.
We found that epilepsy tended to occur between late childhood and adolescence. Episodes of loss of tone of the head and/or the trunk were the most represented seizure types. Generalized tonic-clonic seizures were rarely observed. The typical interictal EEG pattern showed abnormal background activity, with generalized slow spike and wave asynchronous discharge with frontotemporal predominance. Sleep electroencephalography studies also demonstrated abnormal background activity; spindles and K complex were often abnormal in morphology and amplitude. Response to therapy was generally poor and drug resistance was a significant feature.
Although these cases and a review of the literature indicate that epilepsy associated with MECP2 duplication syndrome cannot be considered a useful marker for early diagnosis, epilepsy is present in >90% of adolescent patients and shows a peculiar electroclinical pattern. Consequently, it should be considered a significant sign of the syndrome, and an EEG follow-up of these patients should be encouraged from early childhood. Moreover, the definition of a more specific epileptic phenotype could be useful in order to suspect MECP2 duplication syndrome in older undiagnosed patients.
[Show abstract][Hide abstract] ABSTRACT: We describe a 7-year-old boy with a complex rearrangement involving the whole short arm of chromosome 9 defined by means of molecular cytogenetic techniques. The rearrangement is characterized by a 18.3 Mb terminal deletion associated with the inverted duplication of the adjacent 21,5 Mb region. The patient shows developmental delay, psychomotor retardation, hypotonia. Other typical features of 9p deletion (genital disorders, midface hypoplasia, long philtrum) and of the 9p duplication (brachycephaly, down slanting palpebral fissures and bulbous nasal tip) are present. Interestingly, he does not show trigonocephaly that is the most prominent dysmorphism associated with the deletion of the short arm of chromosome 9. Patient's phenotype and the underlying flanking opposite 9p imbalances are compared with that of reported patients and the proposed critical regions for 9p deletion and 9p duplication syndromes.
[Show abstract][Hide abstract] ABSTRACT: We describe a patient with an abnormal phenotype and a de novo CCR consisting of a reciprocal translocation between chromosomes 1 and 15 and an insertion of an interstitial segment from chromosome 2 within chromosome 1. The CCR was studied by QFQ banding and FISH. The apparently balanced rearrangement was further investigated with array-CGH, that uncovered three cryptic deletions on chromosome 2q. By means of BAC-FISH two deletions were located at the breakpoints of the insertion, at 2q14.3 and 2q31.2, and one at 2q22.2, in the region of 2q translocated on derivative 1. Consequently, in silico analysis of the deleted regions was performed. Among deleted genes, particularly interesting seems to be CNTNAP5, encoding a member of the neurexin superfamily. The three mouse orthologues are highly expressed in adult brain tissues. We speculate that loss of CNTNAP5 might contribute to the developmental language delay of this patient, similar to CNTNAP2, another member of the same protein family, whose alterations have been recently associated with delay in the age at first word in autistic patients. At clinical patient's evaluation, a Mowat-Wilson syndrome (MWS) like appearance was noted. The disease is caused by mutation or deletion of ZEB2 gene, located in our patient 794Kb distally to the 2q22.2 deletion, in the chromosome 2 segment inserted into the derivative 1. The loss of the gene has been excluded by the array-CGH results, but its proximity to the deleted segment and/or its insertion in a different genetic context might influence and consequently impair its expression. Our study confirms that array-CGH is a precious method to identify cryptic imbalances in CCR carriers and underlie the essential role of BAC-FISH as second step of analysis to assess the reciprocal position of the chromosomal segments involved in CCRs and the exact mapping of the imbalances.
No preview · Article · Mar 2009 · European journal of medical genetics
[Show abstract][Hide abstract] ABSTRACT: We have previously shown that the sustained expression of MARK4L transcripts in glioma and neural progenitors (NHNPs) declines after exposure to antisense MARK4L oligonucleotides in glioblastoma cell lines. Array-CGH confirmed the genomic duplication of MARK4L identified by FISH in a glioblastoma cell line. This background together with literature data on the exogenous association of MARK4 with interphase centrosome prompted us to investigate the sub-cellular localization of the endogenous MARK4L protein aiming at achieving insights on its possible role in the pathomechanisms of glioma.
Immunodetection was carried out to validate the specificity of MARK4L antibody in gliomas and NHNPs. Mass spectrometry was applied for MARK4L protein identification in a representative glioblastoma cell line. Combined biochemical fractionation and immunodetection analyses were performed to confirm the sub-cellular localization of MARK4L achieved by immunofluorescence in glioma cell lines.
By assigning MARK4L protein within the band immunoprecipitated by the specific antibody we validated our anti-MARK4L antibody. We demonstrated that the endogenous MARK4L: (i) colocalizes with centrosomes at all mitotic stages and resides in centrosome-enriched fractions; (ii) associates with the nucleolus and the midbody and respective fractions, and (iii) co-stains the aberrant centrosome configurations observed in glioma cell lines.
The overall data merge on the multiplex entry of MARK4L into the cell cycle and link it to the aberrant centrosomes in glioma cell lines suggesting a possible role of this kinase in the abnormal mitotic processes of human glioma.
No preview · Article · Jan 2009 · Cellular oncology: the official journal of the International Society for Cellular Oncology
[Show abstract][Hide abstract] ABSTRACT: Piebald trait leukoderma results from "loss-of-function" mutations in the kit gene. Correlations between mutation type and clinical phenotype have been reported. However, mutation classification has been mainly based on the clinical features of patients. The aim of this study was to get a better understanding of the pathogenesis of human piebaldism by establishing whether the kit mutation type may affect the in vitro survival/proliferation of patient melanocytes. Overall, the research was finalized to implement the clinical application of the autologous cultured epidermis in the treatment of piebald patients. Seven patients, who were transplanted with autologous in vitro reconstituted epidermis, showed an average percentage of repigmentation of 90.7. Six novel and one previously reported mutations were found and their postulated effects discussed in relation to the clinical phenotype and in vitro behavior of epidermal cells. Although mutation type did not impair repigmentation given by autotransplantation, it was shown to influence the survival/proliferation of co-cultured melanocytes and keratinocytes. In particular, tyrosine kinase domain mutations were found with melanocyte loss and keratinocyte senescence during expansion of epidermal cultures. Results indicate that the clinical application of cultured epidermis in piebald patients may be optimized by investigating mutation functional effects before planning surgical operations.
[Show abstract][Hide abstract] ABSTRACT: We report the case of a young boy with fine hair, mild nail dysplasia, blocked nasolacrimal ducts, absence of central incisors, bilateral oligodactyly of feet and anal stenosis. His father showed the same spectrum of anomalies with mild expression. He had mild nail dysplasia, blocked nasolacrimal ducts, inferior dental cysts with consequent premature tooth loss, frequent dental decays consequent to enamel abnormality and cutaneous syndactyly of the second and third right toe. The acro-dermato-ungual-lacrimal-tooth syndrome was suspected and molecular analysis of the P63 gene was performed, but no mutation was found. Although P63 gene analysis was negative, we think that both cases show clinical overlap with the acro-dermato-ungual-lacrimal-tooth syndrome and confirm the wide expression of this condition, even in the same family.
No preview · Article · Nov 2006 · Clinical Dysmorphology
[Show abstract][Hide abstract] ABSTRACT: Alterations in growth factor signaling pathways may be a frequent collaborating event in AML1-ETO-mediated leukemogenesis. Gain-of-function KIT receptor mutations have been reported in adult AML patients, especially those with core binding factor leukemia (CBFL). We have previously reported a new gain-of-function KIT(Asn822Lys) mutation that is constitutively expressed in the Kasumi-1 CBFL cell line, and has recently been described in two childhood AML patients. To explore the molecular basis of the effects of this mutation in the appropriate context of hemopoietic dysregulation, we investigated KIT downstream signaling in the Kasumi-1 cell line by means of STI 571 (Imatinib, Gleevec) pharmacological inhibition.
We investigated KIT(Asn822Lys) mutant-initiated signaling in Kasumi-1 cell line, and characterized the inhibitory effect of the STI 571 protein tyrosine kinase inhibitor on downstream signaling.
The use of STI 571-mediated inhibition impaired the tyrosine phosphorylation of KIT(Asn822Lys) and its association with the p85 subunit of phosphatidylinositol 3'-kinase (p85PI3K). The downstream constitutive phosphorylation of JNK1/2 and STAT3 was also significantly inhibited, but STI 571 had no effect on the constitutive activation of Akt, thus suggesting that it is due to other signaling in Kasumi-1 cells. STI 571 inhibited the KIT-mediated proliferation of Kasumi-1 cells in a dose-dependent manner.
These findings show the role of PI3K in KIT(Asn822Lys)-mediated constitutive activation through the Akt-independent downstream signaling pathway of JNK, and also demonstrate the mutant's susceptibility to STI 571, which may therefore have therapeutic potential in CBFL patients with susceptible KIT mutations.