Absence of karyotype abnormalities in patients with familial urothelial cell carcinoma

OBJECTIVES

In a previous pilot study, a constitutional balanced translocation t(5;20)(p15;q11) was identified in a family with urothelial cell carcinoma (UCC). The purpose of this study was to find (additional) constitutional chromosomal abnormalities in selected families to obtain an indication for genome location(s) of UCC susceptibility gene(s).

METHODS

UCC families were selected through an ongoing study on familial clustering of UCC, the largest study on this subject ever performed. This study included 1193 new patients with UCC of the bladder, ureter, and renal pelvis, identified from the population-based cancer registries of the Dutch Comprehensive Cancer Centers East and South. Information on demographic factors, smoking habits, and family history of UCC was collected by postal questionnaires. UCC in the families was verified with pathology reports. Thirty families were selected in which 2 or 3 individuals were affected, preferably diagnosed at a relatively young age. Blood samples were obtained from all probands, and routine cytogenetic analysis was performed on 23 male and 7 female UCC patients. Subsequent spectral karyotyping was performed in 4 patients from families, which were most suggestive for an inherited etiology.

RESULTS

No aberrant chromosomal features were found by either classical or spectral karyotype analyses.

CONCLUSIONS

It is conceivable that genetic germline abnormalities do exist in the patients in our study but are below the detection limit of the explorative methods used in this study.

Genetic variation in ICF syndrome: evidence for genetic heterogeneity

ICF syndrome is a rare autosomal recessive immunoglobulin deficiency, sometimes combined with defective cellular immunity. Other features that are frequently observed in ICF syndrome patients include facial dysmorphism, developmental delay, and recurrent infections. The most diagnostic feature of ICF syndrome is the branching of chromosomes 1, 9, and 16 due to pericentromeric instability. Positional candidate cloning recently discovered the de novo DNA methyltransferase 3B (DNMT3B) as the responsible gene by identifying seven different mutations in nine ICF patients. DNMT3B specifically methylates repeat sequences adjacent to the centromeres of chromosome 1, 9, and 16. Our panel of 14 ICF patients was subjected to mutation analysis in the DNMT3B gene. Mutations in DNMT3B were discovered in only nine of our 14 ICF patients. Moreover, two ICF patients from consanguineous families who did not show autozygosity (i.e. homozygosity by descent) for the DNMT3B locus did not reveal DNMT3B mutations, suggesting genetic heterogeneity for this disease. Mutation analysis revealed 11 different mutations, including seven novel ones: eight different missense mutations, two different nonsense mutations, and a splice-site mutation leading to the insertion of three aa's. The missense mutations occurred in or near the catalytic domain of DNMT3B protein, indicating a possible interference with the normal functioning of the enzyme. However, none of the ICF patients was homozygous for a nonsense allele, suggesting that absence of this enzyme is not compatible with life. Compound heterozygosity for a missense and a nonsense mutation did not seem to correlate with a more severe phenotype.

DNA hypomethylation and unusual chromosome instability in cell lines from ICF syndrome patients

The ICF syndrome (immunodeficiency, centromeric region instability, facial anomalies) is a unique DNA methylation deficiency disease diagnosed by an extraordinary collection of chromosomal anomalies specifically in the vicinity of the centromeres of chromosomes 1 and 16 (Chr1 and Chr16) in mitogen-stimulated lymphocytes. These aberrations include decondensation of centromere-adjacent (qh) heterochromatin, multiradial chromosomes with up to 12 arms, and whole-arm deletions. We demonstrate that lymphoblastoid cell lines from two ICF patients exhibit these Chr1 and Chr16 anomalies in 61% of the cells and continuously generate 1qh or 16qh breaks. No other consistent chromosomal abnormality was seen except for various telomeric associations, which had not been previously noted in ICF cells. Surprisingly, multiradials composed of arms of both Chr1 and Chr16 were favored over homologous associations and cells containing multiradials with 3 or >4 arms almost always displayed losses or gains of Chr1 or Chr16 arms from the metaphase. Our results suggest that decondensation of 1qh and 16qh often leads to unresolved Holliday junctions, chromosome breakage, arm missegregation, and the formation of multiradials that may yield more stable chromosomal abnormalities, such as translocations. These cell lines maintained the abnormal hypomethylation in 1qh and 16qh seen in ICF tissues. The ICF-specific hypomethylation occurs in only a small percentage of the genome, e.g., ICF brain DNA had 7% less 5-methylcytosine than normal brain DNA. The ICF lymphoblastoid cell lines, therefore, retain not only the ICF-specific pattern of chromosome rearrangements, but also of targeted DNA hypomethylation. This hypomethylation of heterochromatic DNA sequences is seen in many cancers and may predispose to chromosome rearrangements in cancer as well as in ICF.

Immunological tolerance in an HLA non-identical chimeric twin

Blood group chimeric twins offer a unique opportunity to study immunological tolerance in humans. Although this condition is not as rare as previously considered, detailed immunological studies of blood group chimeras are lacking. We describe here a case of secondary chimerism in a dizygotic twin of opposite gender. The karyotypes of the cultured fibroblast confirmed the sex of each twin, all cells in the boy were 46, XY and all cells in the girl were 46, XX. Molecular HLA typing on fibroblasts revealed HLA-DR, DQ and DP disparities between the two siblings. Mixed lymphocyte culture (MLC) revealed a mutual absence of alloreactivity.

Familial syndromic esophageal atresia maps to 2p23-p24

Esophageal atresia (EA) is a common life-threatening congenital anomaly that occurs in 1/3,000 newborns. Little is known of the genetic factors that underlie EA. Oculodigitoesophageoduodenal (ODED) syndrome (also known as "Feingold syndrome") is a rare autosomal dominant disorder with digital abnormalities, microcephaly, short palpebral fissures, mild learning disability, and esophageal/duodenal atresia. We studied four pedigrees, including a three-generation Dutch family with 11 affected members. Linkage analysis was initially aimed at chromosomal regions harboring candidate genes for this disorder. Twelve different genomic regions covering 15 candidate genes (approximately 15% of the genome) were excluded from involvement in the ODED syndrome. A subsequent nondirective mapping approach revealed evidence for linkage between the syndrome and marker D2S390 (maximum LOD score 4.51 at recombination fraction 0). A submicroscopic deletion in a fourth family with ODED provided independent confirmation of this genetic localization and narrowed the critical region to 7.3 cM in the 2p23-p24 region. These results show that haploinsufficiency for a gene or genes in 2p23-p24 is associated with syndromic EA.

Down syndrome in a population of elderly mentally retarded patients: genetic-diagnostic survey and implications for medical care

Ninety-six adults with Down syndrome (DS) from an institutional setting of 591 mentally retarded were investigated systematically with respect to cytogenetic diagnosis, mental functioning and dementia, ophthalmological and audiological abnormalities, and thyroid function. Seventy of the 96 DS patients (73%) were older than 40 years. Only 4.2% were females. Trisomy 21 was found in 86% and mosaic trisomy 21 in 13%. Eighty-two percent of the patients were moderately or severely mentally retarded, 15% were profoundly retarded, and only 3% mildly retarded. Nineteen percent of the patients had dementia. This number increased to 42% of the patients above the age of 50 years. Epileptic seizures were present in 16.7% of all patients, and in 50% of the patients with dementia. Only 17% of the patients in the present study had normal visual acuity, one-third had at least moderately reduced vision. This number increased significantly with age: in the age group 50-59 years almost half of the patients had moderate to severe vision loss. Seventy percent of the patients had moderate, severe, or very severe hearing loss, which was undiagnosed before systematic hearing testing was performed. Increased (48%) or decreased (1%) TSH level was found in 49% of the patients examined for thyroid functions. We suggest a regular screening of all adults with DS to diagnose early dementia, epilepsy, hypothyroidism, and early loss of visual acuity and hearing, with special attention to the group of patients who are severely to profoundly mentally retarded and those with advanced age. Cytogenetic studies are necessary to confirm the clinical diagnosis and are essential for genetic counseling purposes.

X-linked mental retardation: evidence for a recent mutation in a five-generation family (MRX65) linked to the pericentromeric region

We report linkage analysis in a new family with nonspecific X-linked mental retardation, using 27 polymorphic markers covering the entire X-chromosome. We could assign the underlying disease gene, denoted MRX65, to the pericentromeric region, with flanking markers DXS573 in Xp11.3 and DXS990 in Xq21.33. A maximum LOD score of 3.64 was found at markers ALAS2 (Xp11.22) and DXS453 (Xq12) at straight theta = 0. Twenty-five of the 58 reported MRX families are linked to a region that is partially overlapping with the region reported here. Extension of the pedigree showed a number of unaffected distant relatives with haplotypes corresponding to the disease locus. Apparently, a new mutation in a female is causative for the disease in the family reported here. Furthermore, we show the importance of combining clinical, cytogenetic, and molecular studies since one of the family members, expected to be affected by the same genetic defect, has a 48,XXXY karyotype.

Four families (MRX43, MRX44, MRX45, MRX52) with nonspecific X-linked mental retardation: clinical and psychometric data and results of linkage analysis

Four families are described in which mental retardation segregates in an X-linked fashion. Mental retardation was the only consistent clinical finding in all affected males. The degree of retardation varied from mild to profound both between and within families. Linkage analysis localized the genetic defect of MRX43 to Xp22. 31-p21.2, MRX44 to Xp11.3-p11.21, MRX45 to Xp11.3-p11.21, and MRX52 to Xp11.21-q21.33 with LOD scores of >2 at straight theta = 0.0 in all four families.

Localisation of a gene for non-specific X linked mental retardation (MRX46) to Xq25-q26

We report linkage data on a new large family with non-specific X linked mental retardation (MRX), using 24 polymorphic markers covering the entire X chromosome. We could assign the underlying disease gene, denoted MRX46, to the Xq25-q26 region. MRX46 is tightly linked to the markers DXS8072, HPRT, and DXS294 with a maximum lod score of 5.12 at theta=0. Recombination events were observed with DXS425 in Xq25 and DXS984 at the Xq26-Xq27 boundary, which localises MRX46 to a 20.9 cM (12 Mb) interval. Several X linked mental retardation syndromes have been mapped to the same region of the X chromosome. In addition, the localisation of two MRX genes, MRX27 and MRX35, partially overlaps with the linkage interval obtained for MRX46. Although an extension of the linkage analysis for MRX35 showed only a minimal overlap with MRX46, it cannot be excluded that the same gene is involved in several of these MRX disorders. On the other hand, given the considerable genetic heterogeneity in MRX, one should be extremely cautious in using interfamilial linkage data to narrow down the localisation of MRX genes. Therefore, unless the underlying gene(s) is characterised by the analysis of candidate genes, MRX46 can be considered a new independent MRX locus.

Localization of the ICF syndrome to chromosome 20 by homozygosity mapping

Immunodeficiency in association with centromere instability of chromosomes 1, 9, and 16 and facial anomalies (ICF syndrome) is a rare autosomal recessive disorder. ICF patients show marked hypomethylation of their DNA; undermethylation of classical satellites II and III is thought to be associated with the centromere instability. We used DNA from three consanguineous families with a total of four ICF patients and performed a total genome screen, to localize the ICF syndrome gene by homozygosity mapping. One chromosomal region (20q11-q13) was consistently found to be homozygous in ICF patients, whereas all healthy sibs showed a heterozygous pattern. Comparison of the regions of homozygosity in the four ICF patients localized the ICF locus to a 9-cM region between the markers D20S477 and D20S850. Analysis of more families will be required, to refine the map location further. Isolation of the gene associated with the ICF syndrome not only will give insight into the etiology of the ICF syndrome but will also broaden our understanding of DNA methylation processes.

An alternative route for multistep tumorigenesis in a novel case of hereditary renal cell cancer and a t(2;3)(q35;q21) chromosome translocation

Through allele-segregation and loss-of-heterozygosity analyses, we demonstrated loss of the translocation-derivative chromosome 3 in five independent renal cell tumors of the clear-cell type, obtained from three members of a family in which a constitutional t(2;3)(q35;q21) was encountered. In addition, analysis of the von Hippel-Lindau gene, VHL, revealed distinct insertion, deletion, and substitution mutations in four of the five tumors tested. On the basis of these results, we conclude that, in this familial case, an alternative route for renal cell carcinoma development is implied. In contrast to the first hit in the generally accepted two-hit tumor-suppressor model proposed by Knudson, the familial translocation in this case may act as a primary oncogenic event leading to (nondisjunctional) loss of the der(3) chromosome harboring the VHL tumor-suppressor gene. The risk of developing renal cell cancer may be correlated directly with the extent of somatic (kidney) mosaicism resulting from this loss.

Chromosome studies in 1792 males prior to intra-cytoplasmic sperm injection: the Dutch experience

The chance of a male with severe oligozoospermia or azoospermia achieving a pregnancy has undergone a revolutionary increase with the introduction of the intracytoplasmic sperm injection technique (ICSI). However, since ICSI circumvents part of the natural sperm selection mechanisms, the possible transmission of genetic defects to the offspring is a major concern. Cytogenetic analysis is a relatively simple technique to identify at least the carriers of a chromosomal aberration before starting the ICSI procedure. In order to assess the frequency of chromosomal aberrations in male ICSI candidates, we have performed a nationwide cytogenetic study. Of the 1792 males examined, 72 (4.0%) revealed a chromosomal aberration, and one individual even had two. Numerical sex chromosomal aberrations and Robertsonian translocations predominated, followed by reciprocal translocations, inversions and supernumerary marker chromosomes. The different implications, in case a chromosomal aberration is encountered prior to ICSI, are discussed.

A double missense mutation in the ATM gene of a Dutch family with ataxia telangiectasia

Ataxia telangiectasia (AT) is an autosomal recessive disorder characterized by cerebellar ataxia, telangiectasia, immunodeficiency, elevated alpha-fetoprotein levels, chromosomal instability, predisposition to cancer, and radiation sensitivity. We report the identification of a new, double missense mutation in the ataxia telangiectasia gene (ATM) of a Dutch family. This homozygous mutation consists of two consecutive base substitutions in exon 55: a T-->G transversion at position 7875 of the ATM cDNA and a G-->C transversion at position 7876. These transversions were confirmed by polymerase chain reaction/primer-induced restriction analysis with CelII. The double base substitution results in an amino acid change of an aspartic acid to a glutamic acid at codon 2625 and of an alanine to a proline at codon 2626 of the ATM protein. Both amino acids are conserved between the ATM protein and its functional homolog, the Atm gene product in the mouse. Furthermore, the Chou-Fasman and Robson predictions both demonstrate a change in the secondary structure of the ATM protein carrying the D2625E/A2626P mutation. These findings suggest that the double base substitution in the ATM gene is a disease-causing mutation.

Microdeletions of the Y chromosome and intracytoplasmic sperm injection: from gene to clinic

Intracytoplasmic sperm injection (ICSI) is a successful treatment option for severe male infertility, although the aetiology of the disorder remains unclear in most cases. Recently, microdeletions in the AZF region of the Y chromosome have been detected in men with azoospermia or severe oligozoospermia. In this study we investigated the prevalence of microdeletions in the AZF region of the Y chromosome in a population of men undergoing ICSI, and looked for clinical characteristics of men with and without this deletion. Blood was drawn from 164 men, who were on the waiting list for ICSI treatment: 19 were azoospermic, 111 oligozoospermic and 34 normozoospermic (after previous total fertilization failure). A total of 100 men with proven fertility served as a control. Microdeletions in the AZFc region were present in seven of the 111 oligozoospermic men (6.3%). Compared with oligozoospermic men without microdeletions, men with microdeletions had a lower concentration of follicle stimulating hormone (FSH), a lower number of motile spermatozoa and a lower frequency of abnormal findings at andrological history or examination. No microdeletions were found in the azoospermic, normozoospermic and control groups. In conclusion, microdeletions in the AZFc region are relatively frequently found in men with severe unexplained oligozoospermia. In the ICSI era this finding has an important impact because this form of male infertility is now potentially hereditary. Therefore we recommend DNA screening (and genetic counselling) before ICSI, especially in men with normal FSH, severe oligozoospermia and no abnormal clinical andrological findings.

Misinterpretation of trisomy 18 as a pseudomosaicism at third-trimester amniocentesis of a child with a mosaic 46,XY/47,XY, +3/48,XXY, +18 karyotype

False-negative trisomy 18 has been reported after chorionic villus sampling, but not after amniocentesis. We describe a double aneuploidy in cultured amniocytes that was initially misinterpreted as a pseudomosaicism. A patient was referred at 31 weeks of gestation because of fetal anomalies at ultrasound examination. Karyotyping of amniocytes showed a 47,XY, +3 karyotype in 61 clones and a 48,XXY, +18 karyotype in one clone. The latter was interpreted as a pseudomosaicism, the more since a second amniocentesis revealed only cells with a 47,XY, +3 karyotype. At 36 weeks gestational age, a boy was born with congenital anomalies suggestive of trisomy 18. A blood culture showed a 48,XXY, +18 karyotype, while in fibroblasts a 47,XY, + 3/48,XXY, +18 mosaicism was found. Umbilical cord and bladder epithelial tissue also revealed normal 46,XY cells, besides the aneuploid cells. Therefore, the child proper had a 46,XY/47,XY, +3/48,XXY, +18 mosaicism with the clinical symptoms of trisomy 18. To the best of our knowledge, this is the first report of a false-negative result of trisomy 18 together with three sex chromosomes after amniocentesis.

Nijmegen Breakage syndrome: a progress report

We report the findings in the first 30 patients with the Nijmegen Breakage Syndrome (NBS). All had microcephaly from birth, short stature and a 'bird-like' face. Most of them suffered from recurrent respiratory tract infections. Intelligence was normal in half of the patients. Serum immunoglobulins were disturbed in 22/25 patients investigated (IgG deficiency, IgA deficiency, IgG2 and IgG4 deficiency) and T cell defects were found in 23/24 patients tested. The immunodeficiency appears to be more severe than in A-T. Chromosomal aberrations in cultured T lymphocytes occurred preferentially in chromosomes 7 and 14 and at the same breakpoints as in A-T. However, the percentage of chromosome 7 and/or 14 rearrangements was significantly higher in NBS patients than in A-T patients (p < 0.0005). Inv(7) was amongst the most frequently detected aberration in NBS cells as it is in A-T cells. Large clones of cells with rearrangements of chromosome 14 were rare in NBS. Of the first 19 reported patients eight have already developed a malignancy: seven a lymphoma and one a meningioma. It is noteworthy that both the tendency to express rearrangements of chromosomes 7 and 14 and the tendency to develop a malignancy is much higher in NBS than in A-T. Whether there is any causal relationship is as yet unknown.

Segregation of FRAXE in a large family: clinical, psychometric, cytogenetic, and molecular data

During an ongoing study on X-linked mental retardation, we ascertained a large family in which mild mental retardation was cosegregating with a fragile site at Xq27-28. Clinical, psychometric, cytogenetic, and molecular studies were performed. Apart from mild mental retardation, affected males and females did not show a specific clinical phenotype. Psychometric assessment of four representative affected individuals revealed low academic achievements, with verbal and performance IQs of 61-75 and 70-82, respectively. Cytogenetically the fragile site was always present in affected males and was not always present in affected females. With FISH the fragile site was located within the FRAXE region. The expanded GCC repeat of FRAXE was seen in affected males and females either as a discrete band or as a broad smear. No expansion was seen in unaffected males, whereas three unaffected females did have an enlarged GCC repeat. Maternal transmission of FRAXE may lead to expansion or contraction of the GCC repeat length, whereas in all cases of paternal transmission contraction was seen. In striking contrast to the situation in fragile X syndrome, affected males may have affected daughters. In addition, there appears to be no premutation of the FRAXE GCC repeat, since in the family studied here all males lacking the normal allele were found to be affected.

Down-Turner syndrome: case report and review

We present a male patient with Down-Turner mosaicism (45,X/46,X,+21/47,XY,+21) and review 27 similar cases reported so far. Clinical features of Down's syndrome were present in all cases, whereas a combination of features of both Ullrich-Turner syndrome and Down's syndrome was reported in 61% of the patients. However, one has to bear in mind that several stigmata of Ullrich-Turner syndrome can also be present in patients with Down's syndrome and vice versa. In most of the patients two different cell lines were encountered, although cases with one, three, and even four different cell lines have been reported. Of 28 patients, 21 showed female external genitalia, four were phenotypically male, and three showed ambiguous genitalia. Only six patients (21%) carried a Y chromosome, which is far less than expected.

ICF syndrome: a new case and review of the literature

Patients with ICF syndrome can be recognized by the presence of a variable immunodeficiency, instability of the pericentromeric heterochromatin of, in particular, chromosomes 1, 9, and 16 in cultured peripheral lymphocytes, and a number of facial anomalies. Recently, aberrations at the molecular level have been described, consisting of alterations in the methylation pattern of classical satellite DNA, in a number of patients. ICF syndrome is considered to be inherited in an autosomal recessive manner and may be rare, as only 14 patients have been described thus far. We present a new case, a boy with agammaglobulinemia, who was extensively studied by means of classical cytogenetics and fluorescent in situ hybridization. All patients previously reported in the literature are reviewed.

Late-onset ataxia telangiectasia in two brothers presenting with juvenile resting tremor

Two young adult brothers presented with a 5- to 6-Hz resting tremor of the upper limbs. Although ataxia was not unequivocally present and ocular telangiectasia was minimal, typical rearrangements of chromosomes 7 and 14, and increased alpha-feto-protein levels indicated the presence of ataxia telangiectasia (AT). Resting tremor as a predominating symptom in AT is uncommon and to our knowledge has not been described previously.

Mosaic tetrasomy 8p in two patients: clinical data and review of the literature

We report on 2 girls with mosaic tetrasomy 8p. Patient 1 showed the extra iso 8p chromosome in 20% of cultured lymphocytes and 18% of cultured fibroblasts [46,XX/47,XX,+i(8p)]. She presented with growth retardation, mild facial alterations, and motor developmental delay. Patient 2 presented with developmental delay, hypotonia, and slight facial alterations; she had the extra iso 8p chromosome in 94% of cultured peripheral lymphocytes. The patients are compared to the 6 previously reported cases. In our experience, the presently reported patients clinically resemble children with inv dup(8)(p21-p22) and patients with mosaic trisomy 8.

Congenital atrichia, palmoplantar hyperkeratosis, mental retardation, and early loss of teeth in four siblings: a new syndrome?

A syndrome of congenital atrichia, palmoplantar hyperkeratosis, mental retardation, and early loss of teeth was observed in four siblings (three women and one man). The pedigree is suggestive of either an autosomal recessive mode of inheritance or the inheritance of a (small) chromosomal translocation. This combination of findings has not been previously reported and is therefore considered to be a new genetic entity.

Linkage analysis with chromosome 15q11-13 markers shows genomic imprinting in familial Angelman syndrome

Angelman syndrome (AS) and Prader-Willi syndrome (PWS) have become the classical examples of genomic imprinting in man, as completely different phenotypes are generated by the absence of maternal (AS) or paternal (PWS) contributions to the q11-13 region of chromosome 15 as a result of deletion or uniparental disomy. Apparently, most patients are sporadic cases. The genetic mechanism underlying familial AS has remained enigmatic for a long time. Recently, evidence has been emerging suggesting autosomal dominant inheritance of a detectable or undetectable defect in a gene or genes at 15q11-13, subject to genomic imprinting. The present report describes an unusually large pedigree with segregation of AS through maternal inheritance and apparent asymptomatic transmission through several male ancestors. Deletion and paternal disomy at 15q11-13 were excluded. However, the genetic defect is still located in this region, as we obtained a maximum lod score of 5.40 for linkage to the GABA receptor locus GABRB3 and the anonymous DNA marker D15S10, which have been mapped within or adjacent to the AS critical region at 15q11-13. The size of the pedigree allowed calculation of an odds ratio in favour of genomic imprinting of 9.25 x 10(5). This family illustrates the necessity of extensive pedigree analysis when considering recurrence risks for relatives of AS patients, those without detectable deletion or disomy in particular.

The fragile X syndrome: no evidence for any recent mutations

Fragile X (fra(X)) syndrome, the most common form of familial mental retardation, is caused by heritable unstable DNA composed of CGG repeats. As reproductive fitness of fra(X) patients is severely compromised, a high mutation rate has been proposed to explain the high prevalence. However, we have been unable to show any new mutation for 84 probands referred to us to date. We show here the same fra(X) gene in five fra(X) probands with common ancestors married in 1747. The lack of new fra(X) mutations implies that there must be many more fra(X) gene carriers in the population than previously realised. As it is now possible to detect asymptomatic fra(X) gene carriers by DNA analysis, extended family studies for any new proband are recommended. A family illustrating the importance of fra(X) carriership determination is reported.

Partial trisomy for 5q and monosomy for 12p in a liveborn child as a result of a complex five breakpoint chromosome rearrangement in a parent

A balanced complex chromosome rearrangement (CCR) involving four chromosomes is very rare and may lead to different types of aneuploid germ cells. We report a liveborn child with multiple congenital anomalies and an apparently balanced translocation, t(11;12). High resolution chromosome analysis in the mother showed a CCR involving chromosomes 5, 11, 12, and 16. In situ hybridisation showed that this CCR was the result of a five break rearrangement, and that the derivative chromosome 12 consisted of parts of chromosomes 5, 11, and 12. From this it could be deduced that the karyotype of the child was not balanced, but resulted in partial trisomy for 5q and partial monosomy for 12p. The clinical findings in the child were compatible with partial trisomy for 5q.

Penetrance of fra(X) gene: influence of grandparental origin of the gene, mental status of the carrier mother, and presence of a normal transmitting male

Previous studies have indicated that the fragile X [fra(X)] gene does not show full penetrance (mental impairment) in carrier females or "carrier" males. The phenomenon of non-expressing carrier males distinguishes the fra(X) syndrome from all other known X-linked disorders. Moreover, penetrance of the fra(X) gene apparently does not show random distribution within fra(X) families, but seems to be reduced in sibs of normal transmitting males (NTM's). The availability of many large multigeneration fra(X) families, studied by cytogenetic and DNA analyses, enabled us to refine the estimates of the penetrance. From our data we conclude that the penetrance in daughters of carrier females is determined by the mental status of the mother. In sons of carrier females, the observed penetrance appears to be influenced by the grandparental origin of the gene as well as by the mental status of the mother. However, in contrast with the average penetrance, we observed a strongly reduced penetrance of the fra(X) gene in brothers (14%) and sisters (21%) of NTM's. These findings have profound implications for genetic counseling.

Penetrance estimate of the fra(X) gene using Pointer versus direct estimate

Direct estimate of the penetrance of the fra(X) gene was compared with the estimate using the Pointer computer program. Direct estimate gave overall penetrances of 85% for male and 64% for female carriers. The estimates calculated by the Pointer program were 82% for males and 38% for females. It is argued that the use of the Pointer program gives incorrect estimates of the penetrance of the fra(X) gene.

In situ detection of supernumerary aberrations of chromosome-specific repetitive DNA targets in interphase nuclei in human melanoma cell lines and tissue sections

The use of non-radioactive in situ hybridization (ISH) with chromosome-specific repetitive DNA probes to study genomic changes, aneuploidy, and heterogeneity during melanocytic tumor progression, relies on its applicability to non-mitotic interphase nuclei, present in cell suspensions and tissue sections. Therefore, we studied the feasibility of detecting numerical aberrations with respect to the (peri-) centromere regions of chromosomes 1 and 7 in intact nuclei of two human melanoma cell lines with different metastatic behavior in nude mice. In addition, we used paraffin sections from xenograft lesions, obtained by inoculation of these cell lines in nude mice (subcutaneous tumors and spontaneous lung metastases). Paraffin sections from the original primary cutaneous melanoma (with a subepidermal and a dermal part) and two loco-regional metastases were also studied, one of which was the source for the cell lines. These cells and tissues represent examples of materials used in different approaches to the study of melanocytic tumor progression. Regarding the targeted sequences, ISH analysis showed that both cell lines were heterogeneous and aneuploid. The results correlated well with those obtained by ISH on metaphase spreads. Differences between the lines, which could not be detected by flow-cytometric or conventional karyotyping analysis, included data suggestive of a polyploid subpopulation and an extra copy of chromosome 7 in the metastasizing cell line. The polyploid population could be detected also in the paraffin sections of the corresponding subcutaneous xenografts and lung metastases in the mice. Both areas in the patients' primary melanoma could be evaluated separately and showed similar supernumerary aberrations of the chromosome-specific targets. These abnormalities matched those found in both metastases. Our results demonstrate that ISH can be used to visualize genomic abnormalities at the single-cell level in melanocytic nuclei in their natural context, which makes it a promising tool in the histopathology of melanocytic lesions and in the study of melanocytic tumor progression.

Absent thumb, immune disorder, and congenital anemia presenting with hydrops fetalis

A patient is described who presented with severe congenital anemia, hydrops fetalis, immune disorder, and absent thumbs. No toxic, infectious, or metabolic cause was found to explain these symptoms. Immunologic and cytogenetic studies excluded several syndromes that combine radial ray anomalies with hematological involvement. After careful study of the literature, it is concluded that the disorder described here represents a new syndrome that can be added to a growing list of hematological-radial syndromes.

Frequent occurrence of translocations of the short arm of chromosome 15 to other D-group chromosomes

The presence of DA/DAPI (distamycin A/4,6-diamino-2-phenyl-indole) heteromorphism on the short arm of human acrocentric chromosomes was investigated in 127 individuals. In 7 cases, a DA/DAPI signal was observed on an acrocentric chromosome other than 15. Subsequently, in situ hybridization (ISH) with a pericentromeric probe specific for chromosome 15 was carried out. In all 7 cases, three ISH signals were present in every metaphase, i.e., on both chromosomes 15 and on the third DA/DAPI-fluorescence-positive acrocentric chromosome (a chromosome 13 or 14), indicating that a chromosome 15 short arm was also present on these chromosomes. Therefore, we conclude that translocations of short arm sequences from chromosome 15 onto other D-group chromosomes occur frequently. Moreover, it appears that DA/DAPI staining remains specific for the short arm of chromosome 15, despite a number of recent papers suggesting otherwise.

Establishment and characterization of a human melanoma cell line (MV3) which is highly metastatic in nude mice

To select human melanoma cells that are highly tumorigenic and metastatic in nude mice we have implanted fragments of a fresh human melanoma metastasis subcutaneously (s.c.) into a nude mouse. After 3 passages in nude mice, part of the xenograft was cultured and a new melanoma cell line, MV3, was established. After intravenous (i.v.) inoculation of 2 x 10(6) MV3 cells, 95% of the nude mice (n = 20) developed lung colonies within 6 weeks. S.c. inoculation of 2 x 10(6) MV3 cells resulted in 95% tumor take, while 90% of the mice (n = 20) showed spontaneous metastases in the lungs within 7 weeks. Histological and immunohistological features of the original tumor of the patient were largely retained in the tumors of the mice and in the cell line in vitro. As shown by Alcian blue staining, MV3 cells contain large quantities of glycosaminoglycans (GAGs) and/or proteoglycanes (PGs), both in vivo and in vitro. The cells showed a marked expression of transferrin receptor, ICAM-1, EGF-receptor, and VLA-2 integrin. As only few human melanoma cell lines are available that frequently show metastasis in nude mice, the highly metastatic MV3 cell line represents a useful tool for studying the expression and regulation of molecules on human melanoma cells involved in the process of metastasis.

Neither age nor sex influence the expression of folate sensitive common fragile sites on human chromosomes

The expression of folate sensitive common fragile sites was investigated in 82 normal healthy males and females of various ages. In 100 studied metaphases of each of these controls, between 0 and 56 lesions were detected (mean 18.3 +/- 10.3 SD). No significant difference was found between the mean number of expressed lesions in females and males. No age-effects were observed. Two "new" common fragile sites were discovered at 6p21 and 17q21. Their fragile site status, however, needs to be confirmed.

Common fragile sites in man and three closely related primate species

The expression of common fragile sites was studied in peripheral lymphocytes of man, gorilla, chimpanzee, and orangutan after induction with aphidicolin, methotrexate, or fluorodeoxyuridine. As far as the chromosomal localization is concerned, it appears that many of these sites have been highly conserved during primate evolution. However, differences were found in the relative expression of certain sites. In all four species, mapping of approximately 500 lesions disclosed the most breakage-prone common fragile sites, at which about 90% of all induced aberrations were localized. Comparison of chromosome regions involved in evolutionary changes to fragile sites in the four primate species revealed 30 sites that were located at or close to the same chromosomal band. However, no correlation was found between the relative expression of a certain common fragile site in vitro and a potential involvement of this chromosomal site in evolutionary changes.

Marker profile of mesothelial cells versus ovarian carcinoma cells

We investigated the marker profile of human ascitic and cultured mesothelial cells, and compared it to that of ovarian carcinoma cells which are related in terms of their histogenesis, unrelated colon carcinomas being used as reference. Mesothelial and ovarian carcinoma cells could not be distinguished by (intermediate) filament typing, using monoclonal antibodies (MAbs) to keratins, vimentins and desmins. Colon carcinomas differed from mesothelial cells and ovarian carcinomas by the absence of keratin-7 filaments. The epithelial marker BW 495/36 was completely negative on mesothelial cells and positive on all ovarian and colon carcinoma cells. While CEA was found on about 85% of all colon carcinomas, CEA expression on mesothelial cells and ovarian carcinoma cells was below 20%. The ovarian carcinoma markers (OV-TL 3, OV-TL 10, OC 125, MOV 18) were strongly positive on ovarian carcinomas and negative on colon carcinomas (or limited to traces of immunofluorescence on some samples). Although the mesothelial cells showed weak or negative reactivity with these markers, OC 125 antigen was found by immunoelectron microscopy on the surface of cultured mesothelial cells, and was shed in the culture supernatant at concentrations of 50, 28, and 25 CA 125 U/ml/10(4) positive cells. This suggests that mesothelial cells may be responsible for the synthesis of CA 125 in ascitic fluid. The data indicate that ovarian carcinomas, mesothelial cells and colon carcinomas can be distinguished using a combination of anti-keratin antibodies with BW 495/36 and anti-ovarian carcinoma markers.

ETN-1: a new human endometrial carcinoma cell line producing ascites and distant metastases in nude mice

A human carcinoma cell line (ETN-1) has been established from a skin metastasis of a moderately differentiated adenocarcinoma of endometrial origin. The cell line has been so far maintained for 27 months through 55 passages, growing as a monolayer as well as in 3-dimensional clusters with a population doubling time of 72 hr. The number of chromosomes per cell varied from 39 to 107 (average number 61.0 +/- 19.8), with a modal number of 46-48. Seven clonal marker chromosomes were detected. Flow cytometric analysis revealed a population of pseudo-tetraploid cells (DNA index 2.1) next to a pseudo-diploid population (DNA index 1.1). The epithelial character of the cells was confirmed by a positive immunocytochemical reaction using monoclonal antibodies (MAbs) to different keratins, the epithelial cell markers BW 495/36 and HMFG-2, as well as by the presence of many junctional complexes. The tumour cells retained a positive reaction with the anti-ovarian carcinoma OV-TL 3, OV-TL 10 and OC 125 MAbs, although the reaction was markedly diminished in comparison with the original tumour. Tumour cells inoculated subcutaneously in nude mice produced well differentiated adenomatous tumour nodules with formation of glandular lumina and basal lamina. Tumour cells injected intraperitoneally produced malignant ascites and regional as well as distant metastases of adenomatous character.

Characterization of a human ovarian carcinoma cell line, OTN 14, derived from a mucinous cystadenocarcinoma

A human ovarian carcinoma cell line, OTN 14, has been established from malignant ascitic fluid of a patient with a well-differentiated mucinous cystadenocarcinoma of the left ovary. The cell line has been maintained in vitro for 6 months through 23 passages, growing in monolayers as well as in 3-dimensional clusters, with a population doubling time of 28 1/2 hr. The number of chromosomes per cell varied from 67 to 88, with a modal number of 86. Two characteristic marker chromosomes were recognized, consisting of partially deleted chromosome I. With a DNA index of 1.934 the tumour cell line was near tetraploid. The epithelial character of the OTN 14 cells was confirmed by a positive immunofluorescence reaction with monoclonal antibodies (MAbs) against different keratins, and when (immuno)electron microscopy was used, keratin filaments and small junctional complexes were observed. Vimentin was also expressed in these cells, while desmin was not detected. Cultured tumour cells reacted (weakly) positive with MAb OV-TL 3 as a marker for ovarian carcinomas, while reactivity with the anti-ovarian carcinoma MAb OC 125 was limited to a few cells, not permitting the detection of shed CA 125 antigen in the culture supernatant. Cells stained heterogeneously positive for CEA marker BW 431/31, the presence of which was confirmed by detection of CEA shed into the culture medium. The cell line released estradiol at a concentration of 130,000 pmol/L in the culture medium, while no progesterone or dehydroepiandrosterone sulphate were found. Electron microscopical evidence for steroid production was suggested in some cells showing "dense-core" vesicles near the Golgi areas. The OTN 14 tumour cells formed poorly differentiated tumour nodules in nude mice, and metastatic cells were also found in blood capillaries. Cell types with mucinous as well as endocrine characteristics were found.

The most common fragile site in man is 3p14

In man a common fragile site is known to occur at 3p14. We studied the expression of this fragility in a group of 70 normal healthy subjects. Chromosome breaks, chromatid breaks and gaps at 3p14 could be observed in every examined individual, and in a total of 7000 metaphases they were seen in a mean of 4% of cells. Fluorescence studies in ten persons with chromosome No. 3 polymorphism showed that in all cases both Nos. 3 were about equally liable to breakage. A considerable variation in the fra 3p14 expression was found between individuals as well as in repeated cultures from the same person. Neither sex nor age influences could be detected. Cultures with a high percentage of lesions at 3p14 tended to have also a high number of lesions at other sites. Methotrexate and fluorodeoxyuridine markedly enhanced the expression of fra 3p14 and other fragilities. It is concluded that the chromosomal region at 3p14 represents man's most common fragile site, the expression of which seems to be influenced by environmental and heritable factors.

Submicroscopic interstitial deletion of the X chromosome explains a complex genetic syndrome dominated by Norrie disease

Norrie disease (ND), an X-linked recessive disorder, is characterized by congenital blindness followed by bulbar atrophy. We have examined a three-generation family in which ND is part of a complex X-linked syndrome with severe mental retardation, hypogonadism, growth disturbances, and increased susceptibility to infections as additional features. This syndrome is apparently due to an interstitial deletion, as evidenced by the failure of the L1.28 DNA probe (DXS7 locus, Xp11.3) to detect complementary DNA sequences on the defective X chromosome of an affected male and of several obligatory heterozygotes. Attempts to further define this deletion with other DNA probes from the proximal short arm of the X chromosome or by prometaphase chromosome analysis were unsuccessful.

Heritable fragility at 11q13 and 12q13

The chromosomes of two mentally retarded probands were investigated because they were suspected of having the fragile X syndrome. However two other fragilities were detected. In one patient a fra(11)(q13) was found and in the other a fra(12)(q13). Family studies revealed that both fragile sites were real heritable ones. Besides these two heritable fragile sites, the common fragile site at 3p14 was frequently observed. The effects of BUdR, FUdR and methotrexate on the frequency of the three fragilities were studied. The two heritable fragile sites differed from the common fragile site at 3p14 with respect to their inducibility by FUdR and methotrexate.