Chromosomal aberrations of blood lymphocytes induced in vitro by radon-222 daughter alpha-irradiation.

Blood samples were irradiated in vitro with alpha-rays emitted from short-lived radon decay products dissolved in the culture medium at doses between 0.03 and 41.4 mGy. The data were collected from experiments conducted during the period 1984-1992 and comprise a total of about 64000 scored metaphases. For statistical reasons, only 60,022 metaphases were used for the subsequent analysis. The results for total chromosome aberrations and dicentrics indicate a linear dose dependence in the dose range above about 10 mGy, consistent with other experimental observations. At doses below about 10 mGy, aberration frequencies cannot be linearly extrapolated from higher doses, suggesting that there is no dependence on dose within a certain low-dose range. In addition, a statistically significant minimum has been observed at a dose of about 0.03 mGy, which is consistently lower than the related control values. The behavior of the aberration frequencies in the low-dose region seems to be influenced by the control values, which also depend on the environmental radiation burdens to the donors before blood sampling and thus were significantly affected by the Chernobyl fallout.

A new missense substitution at a mutational hot spot of the androgen receptor in siblings with complete androgen insensitivity syndrome.

Several mutations have been described in the human androgen receptor gene including constitutional mutations in androgen insensitivity syndrome, somatic mutations in prostate cancer and triplet expansions in Kennedy's disease (Gottlieb et al. 1997). Here we report on two siblings with complete androgen insensitivity and a novel missense mutation, D695V, in their androgen receptor gene. The two XY females are siblings of German descent and presented at the ages of 23 and 19 years, respectively, with typical clinical features of complete androgen insensitivity. We found both siblings to be hemizygous for a new adenine to thymine transversion at the second nucleotide of codon 695 within the fourth exon of the human androgen receptor gene. The resulting missense mutation D695V is located at the amino-terminal border of the ligand-binding domain of the androgen receptor. The aspartic acid residue at this position is highly conserved in the steroid binding domains of other members of the nuclear receptor family and has already been found to be the site of two other missense mutations associated with androgen insensitivity syndrome (Ris Stalpers et al. 1991, Hiort et al. 1996). Three of four reported subjects showed the complete androgen insensitivity phenotype, in accordance with the two siblings in our study. We suggest that the existence of three pathological amino acid substitutions for aspartic acid 695 most likely reflects the essential role of this residue for normal androgen receptor function in male sexual differentiation.

Variable response to the diepoxybutane test in two dizygotic twins with Fanconi's anemia and flow cytometry for diagnosis confirmation.

Fanconi's anemia (FA) is a rare, genetically heterogeneous, autosomal recessive disorder characterized by bone marrow failure, congenital abnormalities, chromosome instability, and increased susceptibility to neoplasia. Congenital abnormalities vary in location and in severity and not all patients are affected. Although the primary defect of FA is unknown, hypersensitivity to the clastogenic effect of agents that introduce cross-links in the DNA, such as diepoxybutane (DEB), is a marker of the FA phenotype in patients suffering from aplastic anemia without the physical characteristics of the syndrome and, conversely, in cases with abnormalities in the preanemic phase. We report the case of two dizygotic twins suffering from FA with discordant hematologic data. The DEB test repeated several times in various laboratories yielded conflicting results, whereas cell cycle studies by flow cytometry revealed a pattern typical of FA patients. Moreover, the flow cytometric pattern was correlated with the clinical severity of the disease.

Analysis of 65 Turkish patients with congenital aplastic anemia (Fanconi anemia and non-Fanconi anemia): Hacettepe experience.

During the last 14 years, 65 unrelated patients were diagnosed as having constitutional aplastic anemia (CAA). In 52 of 65 patients the diepoxybutane (DEB) test was positive. Comparison of several hematological and clinical parameters in Fanconi anemia (FA) (DEB+) and non-Fanconi anemia (non-FA)(DEB ) patients disclosed no statistically significant differences. The study indicated that in Turkey there were no peculiarities in associated congenital abnormalities in FA and non-FA. The rate of consanguinity was 78% in FA and 46% in non-FA, suggesting that also among the non-FA group recessively inherited disorders are hidden. The mean age at diagnosis in FA was 7.7+/-4.4 (1.8-12) and in non-FA 7.8+/-3.8 (2-15) years. Nine out of 52 FA and five out of 13 non-FA patients died during the follow-up period. Five of the 52 FA patients developed malignancies, three of them had acute myeloblastic leukemia (AML), one a squamous cell carcinoma of the gingiva, and another a hepatocellular carcinoma. Peliosis hepatica occurred in three of the FA and one of the non-FA patients. A total of seven patients stayed in remission without any medication. The remaining 58 patients were given 2-5 mg/kg of oxymetholone and 5 mg prednisolone treatment. Because of sustained remission, oxymetholone therapy was terminated in four of the 45 FA and two of the 13 non-FA patients. Detailed examination of the pedigrees of all of patients indicated the presence of multiple congenital anomalies. In seven of 52 FA and one of 13 non-FA patients there was increased risk for AML and/or other cancers among family members.

Fanconi anemia complementation group E: clinical and cytogenetic data of the first patient.

The clinical and cytogenetic data of the first patient proven to belong to the fifth Fanconi anemia complementation group are described. The Turkish boy presented with psychomotoric retardation, growth retardation, retarded bone age, brachycephaly, hypotelorism, epicanthus, syndactyly, brachydactyly, renal dystopia, and cryptorchism. In addition, an asymmetrical skeletal anomaly was seen with a double distal phalanx of the left thumb and hypoplasia of the right thumb. Typical hematological features of the disorder developed, at the age of 2.5 years, about 1 year after diagnosis. Cytogenetic studies confirmed the clinical diagnosis and revealed a spontaneous chromosomal instability and hypersensitivity to the cross-linking agents diepoxybutane and Trenimon. The findings in the patient, who is considered to be the standard for the fifth Fanconi anemia complementation group, are compared with data reported for other patients affected with Fanconi anemia.

[Medical genetics. Between consultation and molecular genetic research--an analysis of the current status]. / Medizinische Genetik. Zwischen Sprechstunde und molekulargenetischer Forschung--eine Situationsanalyse.

Apparently, there is a much misunderstood discrepancy between the enormous successes achieved by genetic research and clinical applications, which so far have been relatively modest. Rapid progress in the identification of genetic components of diseases and the pathogenetic models derived from the information gained, signals both to the clinician and the patient that "genome analysis" is already available. The present article throws light on the situations in which gene analysis can be applied.

Classification of Fanconi anemia patients by complementation analysis: evidence for a fifth genetic subtype.

Fanconi anemia (FA) is an autosomal recessive disease with diverse clinical symptoms, life-threatening progressive panmyelopathy, and cellular hypersensitivity to cross-linking agents. Currently, 4 genetic subtypes or complementation groups (FA-A through FA-D) have been distinguished among 7 unrelated FA patients. We report the use of genetically marked FA lymphoblastoid cell lines representing each of the 4 presently known complementation groups to classify 13 unrelated FA patients through cell fusion and complementation analysis. Twelve cell lines failed to complement cross-linker sensitivity in fusion hybrids with only 1 of the 4 reference cell lines and could thus be unambiguously classified as FA-A (7 patients), FA-C (4 patients), or FA-D (1 patient). One cell line complemented all 4 reference cell lines and therefore represents a new complementation group, designated FA-E. These results imply that at least 5 genes appear to be involved in a pathway that, when defective, causes bone marrow failure in FA patients.

Comparative evaluation of diepoxybutane sensitivity and cell cycle blockage in the diagnosis of Fanconi anemia.

Fanconi anemia (FA) is a clinically and genetically heterogenous disease that is usually diagnosed on the basis of chromosomal instability reflecting the hypersensitivity towards the DNA cross-linking agents diepoxybutane (DEB) and/or mitomycin C. A less well-known cellular feature that characterizes FA patients is an intrinsic cell cycle disturbance consisting of prolonged progression through, and arrest within, the G2 phase compartment of the cell cycle. In a collaborative blind study, we have evaluated 72-hour lymphocyte cultures from 66 patients with clinical suspicion of FA both for DEB sensitivity and cell cycle disturbance. A concordant result was obtained in 63 of 66 cases. Each of the 3 discordant, but only 1 of the concordant cases presented with overt leukemia. Seventeen cases were identified as classical FA because of their increased DEB sensitivity and G2 phase blockage. Five cases showed a cell cycle disturbance but only borderline DEB sensitivity. These cases might represent atypical or nonclassical forms of FA. They would have been missed by cell cycle studies without concomitant DEB testing. Used in conjunction, cytogenetic and flow cytometric testing provide for the currently optimal diagnosis of FA in nonleukemic patients.

[Risk assessment for familial occurrence of breast cancer]. / Risikoabschätzung für das familiäre Auftreten von Brustkrebs.

There is now unequivocal evidence that an estimated 5% of breast cancer cases is inherited in families. Inherited predisposition of cancer in these families is thought to be the result of a mutation in one of several highly penetrant autosomal dominant genes such as BRCA1 or BRCA2. The BRCA1 gene which is localized on chromosome 17 q was recently isolated and at about the same time BRCA2 was localized to chromosome 13 q. A number of other genetic mutations is also associated with predisposition to breast cancer but accounts for a very small proportion of inherited breast cancer. Many women want to know whether they have inherited a gene predisposing to breast cancer. Those with a family history of breast cancer are particularly concerned about their risk of disease. Currently the assessment of an individual's risk of breast cancer can be undertaken using prediction models based on family history and can be further refined when molecular genetic investigations became available. Without molecular characterisation the Claus tables derived from the Cancer and Steroid Hormone Study data set are best suited to predict breast cancer risk based on age of onset of affected relatives. Direct screening for mutations in breast cancer genes in not yet generally available. Testing for inherited susceptibility is currently being offered to selected families where multiple cases of breast and/or ovarian cancer are diagnosed at an early age (younger than 45 years) as part of research protocols. In these families the so-called indirect gene analysis for linkage of disease to BRCA1 and BRCA2 or the direct analysis of mutations with functional significance in the BRCA1 gene allows relatively refined risk assessment for non-diseased female family members. Some examples will be presented to illustrate risk assessment in different familial and individual situations. Risk assessment including test result interpretation and counselling can be appropriately provided directly to the patient by physicians and genetic counsellors in a coordinated genetic counselling setting.

Molecular analysis of aniridia patients for deletions involving the Wilms' tumor gene.

A human aniridia candidate (AN) gene on chromosome 11p13 has been cloned and characterized. The AN gene is the second cloned gene of the contiguous genes syndrome WAGR (Wilms' tumor, aniridia, genitourinary malformations, mental retardation) on chromosome 11p13, WT1 being the first gene cloned. Knowledge about the position of the AN and WT1 genes on the map of 11p13 makes the risk assessment for Wilms' tumor development in AN patients possible. In this study, we analyzed familial and sporadic aniridia patients for deletions in 11p13 by cytogenetic analyses, in situ hybridization, and pulsed field gel electrophoresis (PFGE). Cytogenetically visible deletions were found in 3/11 sporadic AN cases and in one AN/WT patient, and submicroscopic deletions were identified in two sporadic AN/WT patients and in 1/9 AN families. The exact extent of the deletions was determined with PFGE and, as a result, we could delineate the risk for Wilms' tumor development. Future analyses of specific deletion endpoints in individual AN cases with the 11p13 deletion should result in a more precise risk assessment for these patients.

Clinical, cytogenetic and molecular investigations in three patients with Wolf-Hirschhorn syndrome.

Clinical, cytogenetic and molecular studies were performed in three patients with Wolf-Hirschhorn syndrome (WHS). In all cases the altered chromosome 4 appeared to be the result of a de novo deletion. Cytogenetic investigations located the breakpoint at 4p15.3 and 4p13. With cytogenetic methods it was not possible to decide whether these deletions were terminal or interstitial. DNA methods also failed to define a distal breakpoint within the 4p16.3 region which might have indicated an interstitial deletion. According to the literature, the paternal chromosome 4 is preferentially deleted in most patients with WHS. DNA analysis with polymorphic markers out of the 4p16.3 region revealed that in two of the cases reported here the deleted segment was of paternal and in one case of maternal origin.

Chorionic villus metaphase chromosomes and interphase nuclei analysed by chromosomal in situ suppression (CISS) hybridization.

Metaphase chromosomes and interphase nuclei of chorionic villus samples (CVS) in five cases were studied after treatment with trypsin and post-fixation in formaldehyde by chromosomal in situ suppression (CISS) hybridization. Our modified protocol enables the use of in situ hybridization techniques on CVS preparations after 42 h of culture. A balanced translocation and trisomy 13 were identified with the aid of CISS hybridization.

[Familial hydatidiform mole syndrome and genetic aspects of this disturbed trophoblast development]. / Familiäres Blasenmolen-Syndrom und genetische Aspekte dieser gestörten Trophoblastentwicklung.

A female sibship is presented, where in a total of six sisters aged 16 to 34 years three women suffered from recurrent hydatiform molar pregnancies. Until now none of them has given birth to a child. The family's pedigree and the seven molar events are shown, and cytogenetic findings of complete and incomplete (partial) hydatiform mole as described in the literature and with regard to histomorphological changes. Finally, "genomic imprinting" means that it makes a difference whether chromosomes are derived maternally or paternally (parental origin effect).

Chromosomal in situ suppression hybridization after Giemsa banding.

We report the successive application of classical Giemsa banding and chromosomal in situ suppression hybridization in clinical cytogenetics. The use of both techniques within one protocol requires an additional fixation of the chromosome preparations and an improved suppression of the labelled repetitive sequences. The combination of these two cytological techniques allows the high resolution mapping of translocated Y-chromosomal sequences in the chromosome set of an XX-male.

Chromosomal in situ suppression hybridization of human gonosomes and autosomes and its use in clinical cytogenetics.

DNA libraries from sorted human gonosomes were used selectively to stain the X and Y chromosomes in normal and aberrant cultured human cells by chromosomal in situ suppression (CISS-) hybridization. The entire X chromosome was stained in metaphase spreads. Interphase chromosome domains of both the active and inactive X were clearly delineated. CISS-hybridization of the Y chromosome resulted in the specific decoration of the euchromatic part (Ypter-q11), whereas the heterochromatic part (Yq12) remained unlabeled. The stained part of the Y chromosome formed a compact domain in interphase nuclei. This approach was applied to amniotic fluid cells containing a ring chromosome of unknown origin (47,XY: +r). The ring chromosome was not stained by library probes from the gonosomes, thereby suggesting its autosomal origin. The sensitivity of CISS-hybridization was demonstrated by the detection of small translocations and fragments in human lymphocyte metaphase spreads after irradiation with 60Co-gamma-rays. Lymphocyte cultures from two XX-males were investigated by CISS-hybridization with Y-library probes. In both cases, metaphase spreads demonstrated a translocation of Yp-material to the short arm of an X chromosome. The translocated Y-material could also be demonstrated directly in interphase nuclei. CISS-hybridization of autosomes 7 and 13 was used for prenatal diagnosis in a case with a known balanced translocation t(7:13) in the father. The same translocation was observed in amniotic fluid cells from the fetus. Specific staining of the chromosomes involved in such translocations will be particularly important, in the future, in cases that cannot be solved reliably by conventional chromosome banding alone.

Quality of life of adults with trisomy 21 living in mental retardation homes compared with those staying under parental care.

Genetic counseling today includes providing information about the probability of future behavior and state of health of surviving patients with Down syndrome (DS). Comparative studies on quality of life of DS adults are rare. A consideration for termination of a trisomic fetus is the insecurity, loneliness, and desperation after the death of caring parents. Our study concentrated on the analysis of behavioral data and coping abilities of the patients themselves. We investigated 59 DS adults who live in an institution and 59 DS adults who live at home. The control group consisted of 59 mentally retarded patients with nongenetic disorders in the same institution. The results show significant differences between the "institutionalized" and the "home-care" cohort. Men and women differ in coping with their situations at home, which in turn leads to more interest in homework of women. At working places, this group is more motivated and shows a better mood. In comparison with other mentally retarded adults, those with trisomy 21 are far more socially interested and active. The implication for genetic counseling will be discussed.

[Prenatal sonographic diagnosis of a case of Desbuquois familial osseous dysplasia]. / Pränatale sonographische Diagnose eines Falles von familiärer ossärer Dysplasie Desbuquois.

A rare form of osteodysplasia could be diagnosed by prenatal sonographic screening. Characteristic for this rare type of dysplasia, described only in 8 cases by Desbuqois and Piussan so far, is a severe dwarfism, generalized muscle hypotonia, mental retardation, asynchronized ossification, osteoporosis and considerable desaxiations of tubular bones and articulations. Radiologically, polydactylia and especially an increase in size of the trochanter minor can be observed. In the case described, this autosomal recessive hereditary disease had already been diagnosed for the first child of this consanguineous couple, which had died at 7 weeks after birth. During the second pregnancy of this patient the malformation could be diagnosed by ultrasound in the 24th week of gestation and the pregnancy was terminated. Autopsy and fetogram showed the malformations typical for this rare dysplasia.

International Fanconi Anemia Registry: relation of clinical symptoms to diepoxybutane sensitivity.

Fanconi anemia (FA) is characterized clinically by a progressive pancytopenia, diverse congenital abnormalities and increased predisposition to malignancy. Although a variable phenotype makes accurate diagnosis on the basis of clinical manifestations difficult in some patients, study of cellular sensitivity to the clastogenic effect of DNA cross-linking agents such as diepoxybutane (DEB) has been used to facilitate the diagnosis. Data from DEB-induced chromosomal breakage studies of 328 peripheral blood specimens from patients considered at risk for FA were analyzed using a stepwise multivariate logistic regression, in order to determine which method of representing the data best discriminated between DEB-sensitive (DEB+) and DEB-insensitive (DEB-) cases. Similar methods were applied to the data from the International Fanconi Anemia Registry (IFAR) to determine whether DEB+ and DEB- cases may be considered as distinct clinical entities, and if so, which variables provide the best discrimination between the two groups. We conclude that hypersensitivity to the clastogenic effect of DEB is a useful discriminator for FA. A simplified scoring method for classifying patients on the basis of eight clinical manifestations that are the best predictors for FA is presented. Our data indicate that the clinical diversity in FA is more widespread than previously recognized.

[Ethical considerations in prenatal diagnosis]. / Ethische Uberlegungen zur pränatalen Diagnostik.

PIP: During the last 5 years, debates at universities, professional symposiums, political committees, and Christian acadamies have increasingly addressed prenatal diagnostics and the issue of selective abortion. Prenatal diagnostics may be performed, e.g., by chorionic biopsy, amniotic fluid test, fetoscopy, and dermal biopsy. Since its major objective is to determine the necessity of an abortion it may tragically be construed as a life or death sentence for the fetus. Should a doctor authorize a chromosome diagnosis in order to establish the sex of a fetus when the risk of being the unwanted sex is 50%? Does a desisting doctor share responsibility, if he refers a patient to another doctor, who he knows would willingly perform prenatal diagnostics? The question whether the embryo or fetus has a disease or abnormality that it must live with has become one of whether or not this is acceptable to the parents. Some argue that where certain medical methods exist enough pressure will always be applied for their use regardless of whether they are ethical or not. In most cases, where a normal child is diagnosed the method serves to relax parents and should an abnormal child be diagnosed it prepares them for that eventuality. The original objective of prenatal diagnostics was to enable the healing of fetal diseases, in stark contrast to the "search and destroy mission" slogan. However, the great expectations of performing intrauterine therapy unfortunately have not materialized.^ieng

[Treatment of Fanconi anemia by bone marrow transplantation]. / Die Behandlung der Fanconi-Anämie durch Knochenmarktransplantation.

We report on our experience with allogenic bone marrow transplantation in the treatment of Fanconi anemia. Eight patients were treated, ranging in age from 5 to 17 years. Beside severe hemopoietic insufficiency, all patients exhibited typical cytogenetic abnormalities with an increased rate of chromosomal breaks, while constitutional signs of the disorder were rather variable. Marrow donors were HLA-identical siblings. For conditioning, we used cyclophosphamide at 5 mg/kg on 4 consecutive days followed by thoraco-abdominal irradiation at 5 Gy with full lung shielding. For prophylaxis of graft versus host disease, cyclosporin A was given except in 3 cases who received T-cell depleted marrow. In 2 of the latter cases, graft failure was observed, successfully reversed in one by retransplantation. All others showed prompt and stable engraftment of donor cells. Complications of graft versus host disease developed in 2, requiring prolonged immunosuppressive treatment. Of 8 transplanted patients, 7 survive. With the exception of a recently treated girl, they have normal stable marrow functions. Our results confirm that successful treatment of Fanconi anemia is possible in a majority of patients with HLA-identical donors.