Cost of exome analysis in patients with intellectual disability: a micro-costing study in a French setting

BACKGROUND

With the development of next generation sequencing technologies in France, exome sequencing (ES) has recently emerged as an opportunity to improve the diagnosis rate of patients presenting an intellectual disability (ID). To help French policy makers determine an adequate tariff for ES, we aimed to assess the unit cost per ES diagnostic test for ID from the preparation of the pre-analytical step until the report writing step and to identify its main cost drivers.

METHODS

A micro-costing bottom-up approach was conducted for the year 2018 in a French setting as part of the DISSEQ study, a cost-effectiveness study funded by the Ministry of Health and performed in collaboration with the GAD (Génétique des Anomalies du Développement), a genetic team from the Dijon University Hospital, and a public sequencing platform, the Centre National de Recherche en Génomique Humaine (CNRGH). The analysis was conducted from the point of view of these two ES stakeholders. All of the resources (labor, equipment, disposables and reagents, reusable material) required to analyze blood samples were identified, collected and valued. Several sensitivity analyses were performed.

RESULTS

The unit nominal cost per ES diagnostic test for ID was estimated to be €2,019.39. Labor represented 50.7% of the total cost. The analytical step (from the preparation of libraries to the analysis of sequences) represented 88% of the total cost. Sensitivity analyses suggested that a simultaneous price decrease of 20% for the capture kit and 50% for the sequencing support kit led to an estimation of €1,769 per ES diagnostic test for ID.

CONCLUSION

This is the first estimation of ES cost to be done in the French setting of ID diagnosis. The estimation is especially influenced by the price of equipment kits, but more generally by the organization of the centers involved in the different steps of the analysis and the time period in which the study was conducted. This information can now be used to define an adequate tariff and assess the efficiency of ES.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT03287206 on September 19, 2017.

Wiedemann-Steiner syndrome as a major cause of syndromic intellectual disability: A study of 33 French cases

Wiedemann-Steiner syndrome (WSS) is a rare syndromic condition in which intellectual disability (ID) is associated with hypertrichosis cubiti, short stature, and characteristic facies. Following the identification of the causative gene (KMT2A) in 2012, only 31 cases of WSS have been described precisely in the literature. We report on 33 French individuals with a KMT2A mutation confirmed by targeted gene sequencing, high-throughput sequencing or exome sequencing. Patients' molecular and clinical features were recorded and compared with the literature data. On the molecular level, we found 29 novel mutations. We observed autosomal dominant transmission of WSS in 3 families and mosaicism in one family. Clinically, we observed a broad phenotypic spectrum with regard to ID (mild to severe), the facies (typical or not of WSS) and associated malformations (bone, cerebral, renal, cardiac and ophthalmological anomalies). Hypertrichosis cubiti that was supposed to be pathognomonic in the literature was found only in 61% of our cases. This is the largest series of WSS cases yet described to date. A majority of patients exhibited suggestive features, but others were less characteristic, only identified by molecular diagnosis. The prevalence of WSS was higher than expected in patients with ID, suggesting than KMT2A is a major gene in ID.

MED13L-related intellectual disability: involvement of missense variants and delineation of the phenotype

Molecular anomalies in MED13L, leading to haploinsufficiency, have been reported in patients with moderate to severe intellectual disability (ID) and distinct facial features, with or without congenital heart defects. Phenotype of the patients was referred to "MED13L haploinsufficiency syndrome." Missense variants in MED13L were already previously described to cause the MED13L-related syndrome, but only in a limited number of patients. Here we report 36 patients with MED13L molecular anomaly, recruited through an international collaboration between centers of expertise for developmental anomalies. All patients presented with intellectual disability and severe language impairment. Hypotonia, ataxia, and recognizable facial gestalt were frequent findings, but not congenital heart defects. We identified seven de novo missense variations, in addition to protein-truncating variants and intragenic deletions. Missense variants clustered in two mutation hot-spots, i.e., exons 15-17 and 25-31. We found that patients carrying missense mutations had more frequently epilepsy and showed a more severe phenotype. This study ascertains missense variations in MED13L as a cause for MED13L-related intellectual disability and improves the clinical delineation of the condition.

Bilateral methachronous testicular germ cell tumor and testicular microlithiasis in a child: Genetic analysis and insights. A case report

OBJECTIVES

To report our experience with a case of a child with bilateral testicular micro-lithiasis (TML) who developed bilateral metachronous testicular germ cell tumor (TGCT) and determine the most appropriate follow-up and care management in children with testicular micro calcifications in regards to the theoretical risk of testicular cancer.

CASE REPORT

A 12 year-old boy was diagnosed with TGCT and TML. Ten years after complete remission, he presented with a recurrence on the contralateral testis. Genetic screening was performed on both resected and the patient's karyotype was analyzed.

RESULTS

Blood karyotype was normal. Aberrations were found in the tumor karyotype. CGH array showed alterations in chromosome arm 12p.

DISCUSSION

TML is frequently associated with testicular malignancy in adults: in 16.9% of cases the normal contralateral testicle develops TML in TGCT. Recent works of literature find no relationship between TML and cancer in general, but in patients with additional risks, the relationship becomes stronger. Some authors suggest that environmental components and genetics are determinant factors. This is highly suspected in our reported case. It would seem that TML is not a precancerous lesion per se, but rather a marker of an at-risk situation. Long term evolution is uncertain and regular self-palpation that starts before puberty is the only way to ensure proper screening and monitoring.

CONCLUSION

TML have been suspected to be a sign of testicular dysgenesis syndrome, which yields a risk of developing TGCT in case of noxious associations. In patients with a history of TGCT contralateral TML is alarming and aggressive surgical management should be discussed. Therapeutic education of these patients on self-palpation is the best way to ensure proper follow-up.

[Analysis of prenatal follow-up strategies for trisomy 21 affected pregnancies in France]

OBJECTIVE

The main objective of this study was to screen the prenatal follow-up of women with live birth trisomy 21 child in order to evaluate the proportion of prenatal screening failure versus cases where the women refused either the screening or the prenatal diagnosis of Down syndrome. This study covers the period of time from 2009 to 2012 when the national prenatal screening policy changed from second to first trimester and allows for a comparative assessment of the nationwide efficiency of the various maternal serum marker based strategies.

METHOD

All authorized cytogenetic laboratories sent required data for all cases of trisomy 21 diagnosed in FRANCE in new-borns (less than 1-year-old) from January 2010 to July 2013.

RESULTS

A total of 1253 cases of trisomy 21 were diagnosed before 1 year of age whose mother did not had prenatal diagnosis. For 861 of them, information on the prenatal follow-up was available, with 72% of cases where a prenatal screening was organized either by maternal serum marker or by ultrasound. Results of the screening strategy was positive with maternal serum marker in 28% of cases (calculated risk≥1/250), positive because of abnormal ultrasound in 5% and negative with maternal marker screening (whatever the strategy used) in 67% of cases. Detection rate over the period of the study was 82%, with similar efficiency of first and second trimester strategies (83%) but significantly lower with sequential association of first trimester Nuchal translucency measurement and second trimester serum screening (70%).

CONCLUSION

Switching from second trimester to first trimester screening strategy, with as many trisomy 21 foetuses diagnosed with half invasive procedures fulfilled national health policy objectives. Analysis of these data gives useful insights to elaborate a future screening policy involving cell-free foetal DNA sequencing.

A series of 38 novel germline and somatic mutations of NIPBL in Cornelia de Lange syndrome

Cornelia de Lange syndrome is a multisystemic developmental disorder mainly related to de novo heterozygous NIPBL mutation. Recently, NIPBL somatic mosaicism has been highlighted through buccal cell DNA study in some patients with a negative molecular analysis on leukocyte DNA. Here, we present a series of 38 patients with a Cornelia de Lange syndrome related to a heterozygous NIPBL mutation identified by Sanger sequencing. The diagnosis was based on the following criteria: (i) intrauterine growth retardation and postnatal short stature, (ii) feeding difficulties and/or gastro-oesophageal reflux, (iii) microcephaly, (iv) intellectual disability, and (v) characteristic facial features. We identified 37 novel NIPBL mutations including 34 in leukocytes and 3 in buccal cells only. All mutations shown to have arisen de novo when parent blood samples were available. The present series confirms the difficulty in predicting the phenotype according to the NIPBL mutation. Until now, somatic mosaicism has been observed for 20 cases which do not seem to be consistently associated with a milder phenotype. Besides, several reports support a postzygotic event for those cases. Considering these elements, we recommend a first-line buccal cell DNA analysis in order to improve gene testing sensitivity in Cornelia de Lange syndrome and genetic counselling.

A French collaborative survey of 272 fetuses with 22q11.2 deletion: ultrasound findings, fetal autopsies and pregnancy outcomes

OBJECTIVE

The 22q11.2 deletion (del22q11.2) is one of the most common microdeletions. We performed a collaborative, retrospective analysis in France of prenatal diagnoses and outcomes of fetuses carrying the del22q11.2.

METHODS

A total of 272 fetuses were included. Data on prenatal diagnosis, ultrasound findings, pathological features, outcomes and inheritance were analyzed.

RESULTS

The mean time of prenatal diagnosis was 25.6 ± 6 weeks of gestation. Most of the diagnoses (86.8%) were prompted by abnormal ultrasound findings [heart defects (HDs), in 83.8% of cases]. On fetal autopsy, HDs were again the most common disease feature, but thymus, kidney abnormalities and facial dysmorphism were also described. The deletion was inherited in 27% of cases. Termination of pregnancy (TOP) occurred in 68.9% of cases and did not appear to depend on the inheritance status. However, early diagnosis was associated with a higher TOP rate.

CONCLUSION

This is the largest cohort of prenatal del22q11.2 diagnoses. As in postnatally diagnosed cases, HDs were the most frequently observed abnormalities. However, thymus and kidney abnormalities and polyhydramnios should also be screened for in the prenatal diagnosis of del22q11.2. Only the time of diagnosis appeared to be strongly associated with the pregnancy outcome: the earlier the diagnosis, the higher the TOP rate.

Molecular characterization of 39 de novo sSMC: contribution to prognosis and genetic counselling, a prospective study

Small supernumerary marker chromosomes (sSMCs) are structurally abnormal chromosomes that cannot be characterized by karyotype. In many prenatal cases of de novo sSMC, the outcome of pregnancy is difficult to predict because the euchromatin content is unclear. This study aimed to determine the presence or absence of euchromatin material of 39 de novo prenatally ascertained sSMC by array-comparative genomic hybridization (array-CGH) or single nucleotide polymorphism (SNP) array. Cases were prospectively ascertained from the study of 65,000 prenatal samples [0.060%; 95% confidence interval (CI), 0.042-0.082]. Array-CGH showed that 22 markers were derived from non-acrocentric markers (56.4%) and 7 from acrocentic markers (18%). The 10 additional cases remained unidentified (25.6%), but 7 of 10 could be further identified using fluorescence in situ hybridization; 69% of de novo sSMC contained euchromatin material, 95.4% of which for non-acrocentric markers. Some sSMC containing euchromatin had a normal phenotype (31% for non-acrocentric and 75% for acrocentric markers). Statistical differences between normal and abnormal phenotypes were shown for the size of the euchromatin material (more or less than 1 Mb, p = 0.0006) and number of genes (more or less than 10, p = 0.0009). This study is the largest to date and shows the utility of array-CGH or SNP array in the detection and characterization of de novo sSMC in a prenatal context.

Systematic molecular and cytogenetic screening of 100 patients with marfanoid syndromes and intellectual disability

The association of marfanoid habitus (MH) and intellectual disability (ID) has been reported in the literature, with overlapping presentations and genetic heterogeneity. A hundred patients (71 males and 29 females) with a MH and ID were recruited. Custom-designed 244K array-CGH (Agilent®; Agilent Technologies Inc., Santa Clara, CA) and MED12, ZDHHC9, UPF3B, FBN1, TGFBR1 and TGFBR2 sequencing analyses were performed. Eighty patients could be classified as isolated MH and ID: 12 chromosomal imbalances, 1 FBN1 mutation and 1 possibly pathogenic MED12 mutation were found (17%). Twenty patients could be classified as ID with other extra-skeletal features of the Marfan syndrome (MFS) spectrum: 4 pathogenic FBN1 mutations and 4 chromosomal imbalances were found (2 patients with both FBN1 mutation and chromosomal rearrangement) (29%). These results suggest either that there are more loci with genes yet to be discovered or that MH can also be a relatively non-specific feature of patients with ID. The search for aortic complications is mandatory even if MH is associated with ID since FBN1 mutations or rearrangements were found in some patients. The excess of males is in favour of the involvement of other X-linked genes. Although it was impossible to make a diagnosis in 80% of patients, these results will improve genetic counselling in families.

Microdeletions including YWHAE in the Miller-Dieker syndrome region on chromosome 17p13.3 result in facial dysmorphisms, growth restriction, and cognitive impairment

BACKGROUND

Deletions in the 17p13.3 region are associated with abnormal neuronal migration. Point mutations or deletion copy number variants of the PAFAH1B1 gene in this genomic region cause lissencephaly, whereas extended deletions involving both PAFAH1B1 and YWHAE result in Miller-Dieker syndrome characterised by facial dysmorphisms and a more severe grade of lissencephaly. The phenotypic consequences of YWHAE deletion without deletion of PAFAH1B1 have not been studied systematically.

METHODS

We performed a detailed clinical and molecular characterization of five patients with deletions involving YWHAE but not PAFAH1B1, two with deletion including PAFAH1B1 but not YWHAE, and one with deletion of YWHAE and mosaic for deletion of PAFAH1B1.

RESULTS

Three deletions were terminal whereas five were interstitial. Patients with deletions including YWHAE but not PAFAH1B1 presented with significant growth restriction, cognitive impairment, shared craniofacial features, and variable structural abnormalities of the brain. Growth restriction was not observed in one patient with deletion of YWHAE and TUSC5, implying that other genes in the region may have a role in regulation of growth with CRK being the most likely candidate. Using array based comparative genomic hybridisation and long range polymerase chain reaction, we have delineated the breakpoints of these nonrecurrent deletions and show that the interstitial genomic rearrangements are likely generated by diverse mechanisms, including the recently described Fork Stalling and Template Switching (FoSTeS)/Microhomology Mediated Break Induced Replication (MMBIR).

CONCLUSIONS

Microdeletions of chromosome 17p13.3 involving YWHAE present with growth restriction, craniofacial dysmorphisms, structural abnormalities of brain and cognitive impairment. The interstitial deletions are mediated by diverse molecular mechanisms.

Comparison of liquid based cytology and histology for the evaluation of HER-2 status using immunostaining and CISH in breast carcinoma

BACKGROUND

HER-2 amplification is an important prognostic biomarker and treatment determinant in breast carcinoma.

AIMS

To correlate immunocytochemical (ICC) expression of HER-2 and gene amplification determined by chromogenic in situ hybridisation (CISH) using liquid based cytology (LBC) with immunohistochemistry (IHC) and CISH using histological samples of the same breast carcinomas.

METHODS

Frozen sections and cytobrushings of 103 breast carcinomas were analysed. Four techniques were performed on each tumour: two on LBC samples (ICC, and CISH, both graded as positive, indeterminate, or negative) and two on histological samples (IHC and CISH). Two cell lines (MCF-7, negative; BT 474, positive) were used as controls for cytological analysis. A complementary fluorescence in situ hybridisation technique was carried out in histological samples with low amplification (4-10 dots/nucleus).

RESULTS

Interobserver agreement for the four techniques calculated by the kappa coefficient indicated a substantial agreement. Nine cases failed in cytology because of poor cellularity. Among 94 cases, 19 were amplified; 73, 12, and 9 tumours were scored 0 or 1+, 2+, and 3+, respectively by IHC and 75, 13, and 6, respectively, by ICC. CISH found no amplification in 72 tumours. Correlations between the IHC and CISH results in the histological and cytological samples were always significant.

CONCLUSIONS

Her-2 status could be determined in LBC samples and correlated well with reference histological methods using in situ hybridisation. ICC was less reliable because of the presence of the cytoplasmic membrane. However, these results should be confirmed by a large multicentre study.

Identification of chromosomal loci associated with non-P-glycoprotein-mediated multidrug resistance to topoisomerase II inhibitor in lung adenocarcinoma cell line by comparative genomic hybridization

In order to identify genomic changes associated with an etoposide resistance acquisition, we used comparative genomic hybridization (CGH) to compare a human lung adenocarcinoma cell line, A549 wild type, and three sublines, A549-VP1-3, exposed to increasing concentrations of the topoisomerase II inhibitor, VP16. R-banding karyotype, fluorescence in situ hybridization (FISH), and Southern blot for the MLL gene were also performed. The CGH analysis showed that the A549-VP3 cell line shared chemoresistance-specific abnormalities (amplification of 11q23-qter, loss of chromosome 17, and deletions of 2p14-pter and 2q23-q24). FISH analysis confirmed the loss of one chromosome 17 in the three resistant sublines and revealed an increased fragmentation of chromosome 2 in more than two segments, depending on the etoposide concentration. FISH with an MLL gene probe showed additional signals of MLL (from three in the A549-WT to seven in the A549-VP3 cell line) translocated onto several other chromosomes. Southern blot indicated an amplification of the MLL gene, dependent on the etoposide concentration, without gene rearrangement. The CGH results are suggestive of loci that could be associated with the acquisition of an etoposide-chemoresistant phenotype. Deletion of the 2p region has already been reported, without any candidate gene being identified. The role of MLL in leukemogenesis has previously been demonstrated, but its role in the development of other tumors or its significance in the chemoresistance process remains to be elucidated.

Investigation of nonimmune hydrops fetalis: multidisciplinary studies are necessary for diagnosis--review of 94 cases

This review of 94 cases of nonimmune hydrops fetalis (NIHF) over a 10-year period was undertaken to evaluate the frequency of this pathology among fetal and infant deaths and to determine the most common likely etiologies in a northeastern region of France. NIHF represented 6% of the fetal deaths examined in our laboratory. The combination of findings from morphologic examination of the placenta and fetus with the results of microbiological and cytogenetic investigations (conventional cytogenetic study, fluorescent in situ hybridization [FISH], or DNA ploidy image analysis) led to an etiologic diagnosis for NIHF in two-thirds of the cases and suggested a diagnosis in an additional 23% of cases. The most common causes of NIHF were chromosome abnormalities (33%), infections (16%), and cardiac pathology (13.8%). The detection of a cause for NIHF is important for genetic counseling and management of subsequent pregnancies. Our experience suggests that a diagnosis is possible in a large majority of NIHF when obstetricians and pathologists carefully coordinate the management of prenatal and postnatal investigations and when new techniques, such as molecular biology and DNA quantification, are used.

Gillespie syndrome phenotype with a t(X;11)(p22.32;p12) de novo translocation

PURPOSE

To report a patient with a phenotype suggestive of Gillespie syndrome and with a chromosomal abnormality.

METHODS

Clinical evaluation showed bilateral superior coloboma, foveal hypoplasia, and inferior cerebellar hypoplasia. Karyotyping as well as investigation of the PAX6 gene were performed.

RESULTS

The karyotype of the patient disclosed a de novo translocation t(X;11)(p22.32;p12). Fluorescent in situ hybridization and the search for mutations excluded direct implication of the PAX6 gene.

CONCLUSION

This is, to our knowledge, the first report of a chromosomal abnormality detected in a patient with a Gillespie syndrome phenotype.

Electron tomography of metaphase nucleolar organizer regions: evidence for a twisted-loop organization

Metaphase nucleolar organizer regions (NORs), one of four types of chromosome bands, are located on human acrocentric chromosomes. They contain r-chromatin, i.e., ribosomal genes complexed with proteins such as upstream binding factor and RNA polymerase I, which are argyrophilic NOR proteins. Immunocytochemical and cytochemical labelings of these proteins were used to reveal r-chromatin in situ and to investigate its spatial organization within NORs by confocal microscopy and by electron tomography. For each labeling, confocal microscopy revealed small and large double-spotted NORs and crescent-shaped NORs. Their internal three-dimensional (3D) organization was studied by using electron tomography on specifically silver-stained NORs. The 3D reconstructions allow us to conclude that the argyrophilic NOR proteins are grouped as a fiber of 60-80 nm in diameter that constitutes either one part of a turn or two or three turns of a helix within small and large double-spotted NORs, respectively. Within crescent-shaped NORs, virtual slices reveal that the fiber constitutes several longitudinally twisted loops, grouped as two helical 250- to 300-nm coils, each centered on a nonargyrophilic axis of condensed chromatin. We propose a model of the 3D organization of r-chromatin within elongated NORs, in which loops are twisted and bent to constitute one basic chromatid coil.

Deletions of distal 9p associated with 46,XY male to female sex reversal: definition of the breakpoints at 9p23.3-p24.1

Monosomy of distal 9p is associated in rare cases with abnormalities of testicular determination, which can lead to male to female sex reversal in a 46,XY genetic background. We present two 46,XY individuals partially monosomic for 9p who were raised as females. Definition of the breakpoints using somatic cell hybrids containing only the rearranged chromosome 9 indicated that in the first patient the breakpoint was located between markers D9S256 and D9S144 and in the second patient, the breakpoint was distal to the marker D9S144. In both cases this corresponds to the cytogenetic position 9p23.3-p24.1. Analysis of highly polymorphic microsatellite markers demonstrated a paternal origin of the rearranged chromosome 9 in both patients. These studies define the minimum region associated with male to female sex reversal as 9p24.1-pter.

Loss of sequences 3' to the testis-determining gene, SRY, including the Y pseudoautosomal boundary associated with partial testicular determination

The condition termed 46,XY complete gonadal dysgenesis is characterized by a completely female phenotype and streak gonads. In contrast, subjects with 46,XY partial gonadal dysgenesis and those with embryonic testicular regression sequence usually present ambiguous genitalia and a mix of Müllerian and Wolffian structures. In 46,XY partial gonadal dysgenesis gonadal histology shows evidence of incomplete testis determination. In 46,XY embryonic testicular regression sequence there is lack of gonadal tissue on both sides. Various lines of evidence suggest that embryonic testicular regression sequence is a variant form of 46,XY gonadal dysgenesis. The sex-determining region Y chromosome gene (SRY) encodes sequences for the testis-determining factor. To date germ-line mutations in SRY have been reported in approximately 20% of subjects with 46,XY complete gonadal dysgenesis. However, no germ-line mutations of SRY have been reported in subjects with the partial forms. We studied 20 subjects who presented either 46,XY partial gonadal dysgenesis or 46,XY embryonic testicular regression sequence. We examined the SRY gene and the minimum region of Y-specific DNA known to confer a male phenotype. The SRY-open reading frame (ORF) was normal in all subjects. However a de novo interstitial deletion 3' to the SRY-ORF was found in one subject. Although it is possible that the deletion was unrelated to the subject's phenotype, we propose that the deletion was responsible for the abnormal gonadal development by diminishing expression of SRY. We suggest that the deletion resulted either in the loss of sequences necessary for normal SRY expression or in a position effect that altered SRY expression. This case provides further evidence that deletions of the Y chromosome outside the SRY-ORF can result in either complete or incomplete sex reversal.

Viral integration sites in human papilloma virus-33-immortalized cervical keratinocyte cell lines

The viral organization of HPV-33 was determined by Southern blotting in 2 HPV-33-immortalized cervical cell lines (CK11 and CK12) and compared to our previous results obtained on 10 other already characterized HPV-33-immortalized cell lines (CK1 to CK10). As observed in CK1 to CK10, the viral DNA was found integrated in the cellular genome of CK11 and CK12. However, in CK11 and CK12, the integrated viral genome was deleted and mostly limited to the URR and the E6-E7 ORFs, stressing the importance of those sequences in the immortalization process. Furthermore, CK11 and CK12 showed a unique and identical integration site, as observed in CK1 to CK10, which also harbored HPV-33 integrated at a unique and identical site (which was however different from the one evidenced in CK11 and CK12). Indeed, in situ hybridizations on chromosomes allowed the precise localization of the viral DNA on chromosome 13q33-34 in CK1 to CK10 whereas it was mapped to chromosome 9p13 in CK11 and CK12. We discuss the possibility that integration of HPV-33 at those two particular sites has conferred some growth advantages to the cells and could have thus played a crucial role in the immortalization.

Use of chromosome painting for marker chromosome identification in two children with congenital disorders

Identification of supernumerary de novo marker chromosomes was considered up to now as difficult and sometimes impossible with classical cytogenetical banding methods. The determination of their chromosomal origin is now easier with fluorescent in situ hybridisation techniques and enables an exact correlation between chromosomal aberration and phenotypic features to be established. The authors describe the use of chromosome painting with chromosome 13 and 18 Whole library DNA probe for identification of supernumerary markers in tow patients with congenital disorders. Cytogenetic examination in the first cave revealed a mosaicism with a ring chromosome 13 but clinical findings were different from the classical "ring 13 syndrome', and chromosome painting revealed in an extra--dicentric 13 chromosome (mos : 47, XX, -13, +r (13) +dic (13) / 46, XX, r (13) / 45, XX, -13 / 48, XX, -13, +r (13), (12) dic (13) / 47, XX, -13, + (2) r (13), R-banding pattern on prometaphases and chromosome painting in the second case confirmed the marker to be a 18 p isochromosome (47, XX, +i (18p)). The feasibility and the usefulness of chromosome painting in ascertainment of the possible genetic significance of markers is discussed.

Cytogenetic changes in 67 cranial and spinal meningiomas: relation to histopathological and clinical pattern

The cytogenetic analysis of 67 meningiomas (58 intracranial and 9 spinal tumors) identified chromosomal abnormalities in 63% of cases. When chromosomes involved in numerical and structural changes with a frequency of more than one standard deviation above the mean were considered, distinct cytogenetic patterns could be identified according to sex, anatomical location and histology. The chromosomes more frequently affected were 1, 2, 3, 4, 8, 14, 15, 19, 22, Y. No conclusion could be drawn regarding the prognostic significance of these karyotypic alterations.