Intragenic Deletion in MACROD2: A Family with Complex Phenotypes Including Microcephaly, Intellectual Disability, Polydactyly, Renal and Pancreatic Malformations.

Diagnosing a complex genetic syndrome and correctly assigning the concomitant phenotypic traits to a well-defined clinical form is often a medical challenge. In this work, we report the analysis of a family with complex phenotypes, including microcephaly, intellectual disability, dysmorphic features, and polydactyly in the proband, with the aim of adding new aspects for obtaining a clear diagnosis. We performed array-comparative genomic hybridization and quantitative reverse transcriptase PCR (qRT-PCR) analyses. We identified a deletion of chromosome 20p12.1 involving the macrodomain containing 2/mono-ADP ribosylhydrolase 2 gene (MACROD2) in several members of the family. This gene is actually not associated with a specific syndrome but with congenital anomalies of multiple organs. qRT-PCR showed higher levels of a MACROD2 mRNA isoform in the individuals carrying the deletion. Our results, together with other data reported in the literature, support the hypothesis that the deletion in MACROD2 can affect correct embryonic development and that the presence of another associated event, such as epigenetic modifications at the MACROD2 locus, can influence the level of severity of the pathology.

Retrospective evaluation of bone marrow cell morphology in a cohort of patients with isolated idic(20q-) karyotypic abnormalities.

Isochromosome 20q- (i(20q-)), as a rare reproducible chromosomal anomaly formed on the basis of 20q-, has not been commonly reported. Due to the rarity of this karyotypic anomaly, the bone marrow morphological characteristics of the patients with i(20q-) have not been clarified until now. In this study, the bone marrow cell morphology from MDS patients with isolated i(20q-), isolated 20q-, and normal karyotype was retrospectively compared and statistically analyzed. The results indicated that the isolated i(20q-) was mostly detected in MDS-MLD patients. The frequency and proportion dysplasia of cytoplasmic vacuolization in erythoid cells and small or unusually large size in myeloid cells of isolated i(20q-) MDS patients were significantly higher than those of normal karyotype MDS patients respectively (P < 0.05); the frequency and proportion dysplasia of decreased granules/agranularity in myeloid cells of isolated i(20q-) MDS patients were higher than those of isolated 20q- MDS patients (P < 0.05). The incidence of some specific morphological manifestations, such as deeply lobulated and hyperlobulated megakaryocytes and hypogranular and vacuolized eosinophils, may be an important morphological implication for the anomaly of isolated i(20q-). These morphological features of dysplasia may be helpful in distinguishing MDS with isolated i(20q-) from those with isolated 20q- and normal karyotype.

[Electroclinical characteristics of a patient with ring chromosome 20 syndrome]. / Características electroclínicas de un paciente con síndrome del cromosoma 20 en anillo.

INTRODUCTION: The ring chromosome 20 syndrome (r20) is a rare genetic disorder with a late diagnosis. CASE REPORT: A 17 year old boy with drug-resistant epilepsy of 14 years of evolution, which has moderate mental retardation, behavioral alterations and seizures consisting of complex non-convulsive status and generalized seizures during wakefulness, along with more subtle epileptic manifestations during sleep. Karyotype in peripheral blood showed the existence of a ring chromosome 20, whose breakpoints were p13q13.3, presenting a mosaicism 46,XY[23]/46,XY,r(20)(p13q13.3)[25]. CONCLUSIONS: The epileptic r20 syndrome seems to have a characteristic electroclinical phenotype and, although not pathognomonic, should be sufficient for all patients who meet a karyotype in peripheral blood, thus avoiding multiple trials with unnecessary drugs and exhaustive studies. In this sense, the study of sleep EEG may be helpful.

TITLE: Caracteristicas electroclinicas de un paciente con sindrome del cromosoma 20 en anillo.Introduccion. El sindrome del cromosoma 20 en anillo (r20) es una alteracion genetica infrecuente, con un diagnostico tardio. Caso clinico. Varon de 17 años con epilepsia farmacorresistente de 14 años de evolucion, que presentaba retraso mental moderado, alteraciones conductuales y crisis epilepticas consistentes en estados complejos no convulsivos y crisis generalizadas durante la vigilia, junto con manifestaciones epilepticas mas sutiles durante el sueño. El estudio del cariotipo en sangre periferica mostro la existencia de un cromosoma 20 en anillo, cuyos puntos de corte parecen ser p13q13.3, y presento un mosaicismo 46,XY[23]/46,XY,r(20)(p13q13.3)[25]. Conclusiones. El sindrome epileptico r20 parece tener un fenotipo electroclinico caracteristico y, aunque no es patognomonico, deberia ser suficiente para realizar en todos los pacientes que lo cumplan un cariotipo en sangre periferica, que evite asi los multiples ensayos con farmacos y estudios exhaustivos innecesarios. En ese sentido, el estudio electroencefalografico de sueño puede resultar de gran ayuda.

Familial subtelomeric rearrangement of chromosomes 19 and 20: a new contribution to partial distal 19q trisomy.

The role of cryptic translocations in human syndromes is a matter of fact, though this phenomenon is apparently rare. Apart from episodic case reports due to the increasing application of new molecular cytogenetic techniques, no data on its frequency in the general population are currently available. Rearrangements due to the unbalanced segregation of cryptic translocations are found in many anomalies responsible for different clinical pictures. In nearly 50% of cases, subtelomeric abnormalities are inherited from a parent carrying a balanced cryptic chromosome rearrangement. To date, very few cases of partial trisomies of 19q have been reported, with different breakpoints. Involvement of the distal region 19q is even more rare, and the delineation of its main clinical characteristics is still vague and awaiting better definition. We report two new cases of partial 19q13.42-qter trisomy associated with a partial 20p13-pter monosomy in a family found to have the cryptic translocation t(19;20)(q13.42;p13). We investigated a 5-year-old boy and his 49-year-old paternal uncle, and both had a similar, previously unrecognized mental retardation pattern, associated with the same subtelomeric rearrangement.

Chromosomal breakpoints characterization of two supernumerary ring chromosomes 20.

The occurrence of an additional ring chromosome 20 is a rare chromosome abnormality, and no common phenotype has been yet described. We report on two new patients presenting with a supernumerary ring chromosome 20 both prenatally diagnosed. The first presented with intrauterine growth retardation and some craniofacial dysmorphism, and the second case had a normal phenotype except for obesity. Conventional cytogenetic studies showed for each patient a small supernumerary marker chromosome (SMC). Using fluorescence in situ hybridization, these SMCs corresponded to ring chromosomes 20 including a part of short and long arms of chromosome 20. Detailed molecular cytogenetic characterization showed different breakpoints (20p11.23 and 20q11.23 for Patient 1 and 20p11.21 and 20q11.21 for Patient 2) and sizes of the two ring chromosomes 20 (13.6 Mb for case 1 and 4.8 Mb for case 2). Review of the 13 case reports of an extra r(20) ascertained postnatally (8 cases) and prenatally (5 cases) showed varying degrees of phenotypic abnormalities. We document a detailed molecular cytogenetic chromosomal breakpoints characterization of two cases of supernumerary ring chromosomes 20. These results emphasize the need to characterize precisely chromosomal breakpoints of supernumerary ring chromosomes 20 in order to establish genotype-phenotype correlation. This report may be helpful for prediction of natural history and outcome, particularly in prenatal diagnosis.

Chromosome 20 deletions in myelodysplastic syndromes and Philadelphia-chromosome-negative myeloproliferative disorders: characterization by molecular cytogenetics of commonly deleted and retained regions.

Deletion of the long arm of chromosome 20 is a recurrent abnormality observed in myelodysplastic syndromes (MDS) and in Philadelphia-chromosome-negative myeloproliferative disorders (MPD). Our objective was to characterize the deletion size among 38 MDS and MPD patients using fluorescence in situ hybridization (FISH) with bacterial artificial chromosome (BAC) probes and to define commonly deleted and retained regions on chromosome 20. Patients were distributed in three groups according to the World Health Organization classification: MDS (22 patients), MPD (12 patients) and myelodysplastic/myeloproliferative diseases (four patients). FISH with centromeric, subtelomeric, and unique sequence probes was performed to characterize the deletion whereas its size was delineated using BAC clones. All 38 deletions were found to be interstitial. A commonly deleted region was identified for each of the three groups; it varied from 6.62 to 10.4 Mb and showed considerable overlapping. Two commonly retained regions (CRR), also showing overlapping, were identified in all three groups, one in the centromeric region, the other in the telomeric region. The deletion size is highly variable, with no apparent recurrent breakpoint. The deletion may result in the loss of one or several tumor suppressor genes but the target genes remain unknown. Loss of genes plays an important part in the myeloid leukemic process associated with del(20q). However, genes located in the retained chromosomal regions may also play a role in the oncogenetic mechanisms.

The C20orf133 gene is disrupted in a patient with Kabuki syndrome.

BACKGROUND: Kabuki syndrome (KS) is a rare, clinically recognisable, congenital mental retardation syndrome. The aetiology of KS remains unknown. METHODS: Four carefully selected patients with KS were screened for chromosomal imbalances using array comparative genomic hybridisation at 1 Mb resolution. RESULTS: In one patient, a 250 kb de novo microdeletion at 20p12.1 was detected, deleting exon 5 of C20orf133. The function of this gene is unknown. In situ hybridisation with the mouse orthologue of C20orf133 showed expression mainly in brain, but also in kidney, eye, inner ear, ganglia of the peripheral nervous system and lung. CONCLUSION: The de novo nature of the deletion, the expression data and the fact that C20orf133 carries a macro domain, suggesting a role for the gene in chromatin biology, make the gene a likely candidate to cause the phenotype in this patient with KS. Both the finding of different of chromosomal rearrangements in patients with KS features and the absence of C20orf133 mutations in 19 additional patients with KS suggest that KS is genetically heterogeneous.

Karyotype and molecular cytogenetic studies in polycythemia vera.

A minority of patients with newly diagnosed polycythemia vera (PV) have an abnormal karyotype in their myeloid cells but no invariant chromosomal aberration has been found. The most frequent visible alteration is a 20q deletion, also characterized in other myeloproliferative diseases (MPD) and myeloid malignancies; among other chromosomal changes, trisomy 9 appears more common in PV than in other MPDs. When a myelofibrosis complicates the course of the disease, cytogenetic anomalies become quite common with a striking frequency of partial duplication 1q; an evolution towards myelodysplasia or acute leukemia is almost always associated with nonspecific chromosomal aberrations. Modern cytogenetic methods have disclosed cryptic anomalies and pointed out the high frequency of 9p alterations affecting a restricted region, thus stimulating an active search for candidate genes or specific mutations.

MDS/AML-associated cytogenetic abnormalities in multiple myeloma and monoclonal gammopathy of undetermined significance: evidence for frequent de novo occurrence and multipotent stem cell involvement of del(20q).

Multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS) are characterized cytogenetically by 14q32 rearrangements, -13/13q-, and various trisomies. Occasionally, karyotypic patterns characteristic of myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML) occur in MM, often signifying therapy-related (t)-MDS/t-AML. Comparison of cytogenetic features in all published MMs (n = 993) and t-MDS/t-AML post-MM (n = 117) revealed significant differences in complexity and ploidy levels and in most genomic changes. Thus, these features often can be used to distinguish between MM and t-MDS/t-AML. Rarely, myeloid-associated aberrations are detected in MM without any signs of MDS/AML. To characterize such abnormalities in MM/MGUS, we ascertained all 122 MM and 26 MGUS/smoldering MM (SMM) cases analyzed in our department. Sixty-six (54%) MMs and 8 (31%) MGUS/SMMs were karyotypically abnormal, of which 6 (9%) MMs and 3 (38%) MGUS/SMMs displayed myeloid abnormalities, that is, +8 (1 case) and 20q- (8 cases) as the sole anomalies, without any evidence of MDS/AML. One patient developed AML, whereas no MDS/AML occurred in the remaining 8 patients. In one MGUS with del(20q), fluorescence in situ hybridization analyses revealed its presence in CD34+CD38- (hematopoietic stem cells), CD34+CD38+ (progenitors), CD19+ (B cells), and CD15+ (myeloid cells). The present data indicate that 20q- occurs in 10% of karyotypically abnormal MM/MGUS cases and that it might arise at a multipotent progenitor/stem cell level.

PET evidence for a role of the basal ganglia in patients with ring chromosome 20 epilepsy.

BACKGROUND: Studies in animal models and epileptic patients have suggested that circuits of the basal ganglia may control epileptic seizures and that striatal dopaminergic transmission plays a key role in seizure interruption. Ring chromosome 20 (r[20]) epilepsy is a very homogenous type of epilepsy and is clinically characterized by long-lasting seizures suggesting a dysfunction in the seizure control system. The hypothesis that these long-lasting seizures are associated with a reduction of striatal dopamine was addressed in the present study in drug-resistant patients with r(20) epilepsy using PET. METHOD: The authors performed [18F]fluoro-l-DOPA PET in 14 patients with r(20) epilepsy and compared uptake constants in the putamen and the caudate with those of 10 controls. In addition, the authors examined the correlation between these constants and the percentage of cells with r(20) mosaicism. RESULTS: [18F]fluoro-l-DOPA uptake was significantly decreased bilaterally in the putamen and in the caudate nucleus of patients. This reduction was equal for both nuclei and was not correlated to the percentage of cells with r(20). CONCLUSION: Striatal dopamine is modulated in r(20) epilepsy; dysfunction of this neurotransmission may impair the mechanisms that interrupt seizures.

High-resolution analysis of DNA copy number alterations in colorectal cancer by array-based comparative genomic hybridization.

Array-based comparative genomic hybridization (CGH) allows for the simultaneous examination of thousands of genomic loci at 1-2 Mb resolution. Copy number alterations detected by array-based CGH can aid in the identification and localization of cancer causing genes. Here we report the results of array-based CGH in a set of 125 primary colorectal tumors hybridized onto an array consisting of 2463 bacterial artificial chromosome clones. On average, 17.3% of the entire genome was altered in our samples (8.5 +/- 6.7% gained and 8.8 +/- 7.3% lost). Losses involving 8p, 17p, 18p or 18q occurred in 37, 46, 49 and 60% of cases, respectively. Gains involving 8q or 20q were observed 42 and 65% of the time, respectively. A transition from loss to gain occurred on chromosome 8 between 41 and 48 Mb, with 25% of cases demonstrating a gain of 8p11 (45-53 Mb). Chromosome 8 also contained four distinct loci demonstrating high-level amplifications, centering at 44.9, 60, 92.7 and 144.7 Mb. On 20q multiple high-level amplifications were observed, centering at 32.3, 37.8, 45.4, 54.7, 59.4 and 65 Mb. Few differences in DNA copy number alterations were associated with tumor stage, location, age and sex of the patient. Microsatellite stable and unstable (MSI-H) tumors differed significantly with respect to the frequency of alterations (20 versus 5%, respectively, P < 0.01). Interestingly, MSI-H tumors were also observed to have DNA copy number alterations, most commonly involving 8q. This high-resolution analysis of DNA copy number alterations in colorectal cancer by array-based CGH allowed for the identification of many small, previously uncharacterized, genomic regions, such as on chromosomes 8 and 20. Array-based CGH was also able to identify DNA copy number changes in MSI-H tumors.

The role of protein elongation factor eEF1A2 in ovarian cancer.

Frequent gains of chromosome 20q12-13 in ovarian tumors indicate that at least one important oncogene is found at that locus. One of the genes there is EEF1A2, which maps to 20q13.3 and encodes protein elongation factor eEF1A2. This review will focus on recent evidence indicating that EEF1A2 is an important ovarian oncogene and that the protein elongation network can activate tumorigenesis and inhibit apoptosis.

A unique clone involving multiple structural chromosome rearrangements in a myelodysplastic syndrome case.

In a young female patient presenting with a myelodysplastic syndrome (MDS), a unique clone involving six structural chromosome rearrangements was identified using G-banding and molecular cytogenetic techniques. Fifty GTG-banded metaphases from bone marrow were initially analyzed and all metaphases contained all of the six structural chromosome rearrangements. To further define the GTG-banded karyotype, a series of fluorescence in situ hybridization and primed in situ labeling experiments were performed and the karyotype was then characterized as: 46,XX,r(5)(p13q13),der(20)t(5;20),dup(11)(p11.2p15), r(11)(p15q25),del(13)(q14),idic(22)(p11). The patient quickly progressed to acute nonlymphocytic leukemia three months after the diagnosis and died of a hemorrhage in the brain parenchyma two months later. In this case, the multiple structural chromosome rearrangements conferred an obvious cellular proliferative advantage and indicated a very poor prognosis. Considering that multiple chromosome abnormalities associated with MDS transformation are often polyclonal, this unique clone involving six structural chromosome rearrangements make our case highly unusual.

Generation of the NUP98-TOP1 fusion transcript by the t(11;20) (p15;q11) in a case of acute monocytic leukemia.

A rare chromosomal translocation, (11;20)(p15;q11), was detected in a 29-year-old male patient diagnosed with acute monocytic leukemia (AMoL) according to the French-American-British classification criteria. Whole chromosome painting analysis with paints for chromosomes 11 and 20 confirmed the result of conventional cytogenetic analysis. Reverse transcriptase polymerase chain reaction revealed the NUP98-TOP1 fusion transcript. To our knowledge, this is the second report of the translocation involving NUP98 and TOP1 genes in AMoL. On reviewing the literature, we suggest that t(11;20)(p15q11) is associated with myelocytic disorders rather than lymphocytic proliferative diseases.

Novel chromosome findings in bladder cancer cell lines detected with multiplex fluorescence in situ hybridization.

Bladder cancer is a common neoplasm worldwide, consisting mainly of transitional cell carcinomas, while squamous, adenocarcinoma, and sarcomatoid bladder cancers account for the remaining cases. In the present study, multiplex fluorescence in situ hybridization (M-FISH) has been used to characterize chromosome rearrangements in eight transitional and one squamous cell carcinoma cell line, RT112, of UMUC-3, 5637, CAT(wil), FGEN, EJ28, J82, 253J, and SCaBER. Alterations of chromosome 9 are the most frequent cytogenetic and molecular findings in transitional cell carcinomas of all grades and stages, while changes of chromosomes 3, 4, 8, 9, 11, 14, and 17 are also frequently observed. In the present study, alterations previously described, including del(8)(p10), del(9)(p10), del(17)(p10), and overrepresentation of chromosome 20, as well as several novel findings, were observed. These novel findings were a del(15)(q15) and isochromosome 14q, both occurring in three of nine cell lines examined. These abnormalities may reflect changes in bladder tumor biology. M-FISH represents an effective preliminary screening tool for the characterization of complex tumor karyotypes.

Involvement of the NUP98 gene in a chromosomal translocation t(11;20)(p15;q11.2) in a patient with acute monocytic leukemia (FAB-M5b).

We report here a case of acute monocytic leukemia (M5b subtype according to the French-American-British [FAB] classification) with chromosomal translocation t(11;20)(p15;q11.2). Fluorescence in situ hybridization analysis with a probe for the NUP98 gene, which is located at chromosome band 11p15, showed that the probe hybridized to both derivative chromosomes 11 and 20 as well as to the remaining normal chromosome 11, indicating that the NUP98 gene was split and involved in this translocation. This is the first report of t(11;20)(p15;q11.2) involving the NUP98 gene in overt leukemia.

[Ring chromosome 20: an epileptic channel disorder?]. / Cromosoma 20 en anillo: una canalopatía epiléptica?

INTRODUCTION: The ring-shaped chromosome 20 (r20) syndrome is an infrequent chromosopathy which is associated with epileptic seizures, behaviour disorders and mental retardation. It results from the fusion of the two arms of the chromosome with deletion of the telomeric portions. CLINICAL CASE: We present a case of r20, review published cases and describe the clinical and neurophysiological characteristics. CONCLUSIONS: The r20 syndrome is the third type of epilepsy known to be of genetic basis related to chromosome 20. It has clinical and neurophysiological characteristics which give it a distinctive character and are easily identified. The fact that on locus 20q13 (telomeric portion of the long arm of chromosome 20) two genes related to epileptic channelopathies (CHRNA4 and KCNQ2) have been described, suggest the hypothesis that the subjacent deletion in cases of r20 syndrome affect one of these genes and explains the epileptogenicity. We consider this hypothesis and the possibility that r20 syndrome may be an epileptic channelopathy.