An abnormal terminal X-Y interchange accounts for most but not all cases of human XX maleness

To determine if human XX maleness results from an abnormal chromosomal X-Y interchange, we studied the inheritance of the paternal pseudoautosomal region in nine patients. Those six patients in whom Y-specific DNA was found (Y(+)) inherited the entire pseudoautosomal region from the paternal Y chromosome and lost that of the paternal X chromosome. Moreover, in three Y(+) cases, we observed the deletion of a paternal Xp locus tightly linked to the pseudoautosomal region. These results definitively show that an abnormal and terminal X-Y interchange during paternal meiosis causes Y(+)XX maleness. In contrast, no abnormal X-Y interchange was observed in any of the three Y(-) cases analyzed, suggesting that maleness can occur in the absence of any Y-specific DNA.

Pallister-Killian syndrome: cytogenetic and molecular studies

Pallister-Killian syndrome is a dysmorphic syndrome characterized by a tissue-limited mosaicism: a majority of fibroblasts have 47 chromosomes with an extra small metacentric chromosome, whereas the karyotype of lymphocytes is normal. In this study, the interpretation of the extra chromosome as composed of two short arms of chromosome 12 is confirmed, using molecular methods. Furthermore, restriction fragment length polymorphisms indicate that the two arms are identical, which is compatible with the hypothesis of an isochromosome 12p. A new feature which may be important in understanding the mechanism of origin of the abnormality is described: the proportion of abnormal mitoses falls dramatically during long-term culture of fibroblasts.

Choroideremia: close linkage to DXYS1 and DXYS12 demonstrated by segregation analysis and historical-genealogical evidence

Linkage studies using restriction fragment length polymorphisms were conducted in the X-linked disorder, choroideremia, designated TCD for Progressive Tapeto-Choroidal Dystrophy. Previously demonstrated close linkage with locus DXYS1 was confirmed (lod 11.44 at 0 recombination distance). In addition, locus DXYS12 was found to be closely linked with TCD (lod 3.31 at 0 recombination distance). The disease mainly occurs in three large kindreds in remote Northern Finland. While formal genealogical proof is lacking, all presently living (more than 80 affected males and 120 carrier females) probably originate from a common founder couple born in 1644 and 1646, twelve generations ago. All 36 patients and 48 carriers tested from the three kindreds had the same haplotype (TCD/DXYS1, 11kb/DXYS12, 1.6kb). Given that at least 105 female meioses transmitting TCD have occurred since 1650 in these kindreds, extremely close linkage between TCD, DXYS1 and DXYS12 is suggested. The above haplotype is a very useful diagnostic tool in these TCD families. We suggest that our historical-genealogical approach to linkage analysis may be possible elsewhere in similar isolated populations.

Constitutional translocation t(3;6)(p14;p11) in a family with hematologic malignancies

We describe a family with an inherited constitutional balanced translocation t(3;6)(p14;p11) and hematologic malignancies. Of two proven translocation carriers, one had acute myeloid leukemia and the other had myelofibrosis. A third member who had died of acute leukemia was a possible translocation carrier (chromosome analysis had not been performed). Five healthy translocation carriers were detected. Neither the translocation nor additional hematologic malignancies were found outside the nuclear family. It could not be definitely clarified if this constitutional translocation predisposes to hematologic malignancies. Breakpoint 3p14 has previously been implicated in recurrent cancer-associated rearrangements but 6p11 has not. We suggest that other investigators look for involvement of these breakpoints in cancer patients.

Monosomy 7 in granulocytes and monocytes in myelodysplastic syndrome

Monosomy for all or part of chromosome 7 in bone marrow mitoses of some patients with myelodysplastic syndrome or acute nonlymphocytic leukemia has been associated with a defect in granulocyte function. To study which blood-cell lineages are affected by the monosomy, we used chromosome 7-specific DNA probes in Southern blotting experiments on DNA derived from specific cell fractions isolated from the blood of five patients. As judged by the presence or absence of two different alleles for restriction-fragment-length polymorphisms, lymphocytes of all five patients were shown to have two different chromosomes 7. Granulocytes were affected by the chromosomal abnormality in four patients (No. 1, 2, 4, and 5) and unaffected in one (No. 3). Chemotaxis was normal in Patient 3 and impaired in Patients 4 and 5. Monocytes were affected by the monosomy in two of three patients (No. 2 and 3) and mainly unaffected in one (No. 1). Thus, the granulocytes and monocytes were affected differently in different patients. We conclude that mature blood cells are derived from abnormal progenitors and that there may be heterogeneity in the involvement of different cell lineages in different patients with myelodysplastic syndrome or acute nonlymphocytic leukemia. There is an association between DNA loss and functional impairment.

Bone marrow cytogenetics: the lineage of dividing cells changes during the first few hours in culture

To determine changes in the cell lineages of metaphases karyotyped following different culture times, marrow from 11 healthy individuals was studied using a technique that allows simultaneous analysis of karyotype and cell lineage. Cell lineage was identified as erythroid by surface glycophorin A, granulocytic by Sudan black B and PM-81, and monocytic by lysozyme. Marrow examined sequentially showed granulocytic mitoses to initially decrease from a mean of 40% at 1.75 hr to 6% at 3.5 hr and then increase, being 46% by 6 hr and 82% after 1 day, and remain high for the 10 days studied. Erythroid mitoses were most frequent (mean, 72%) at 3.5 hr and then decreased rapidly, being 16% by 6 hr, 7% at 1 day, and absent thereafter. When granulocytic mitoses were least frequent, 20-36% of mitoses were also unreactive with glycophorin A. Double staining experiments to identify these cells found some to be monocytic, but most remained unidentified. The authors conclude that mitoses of different hematopoietic lineages predominate when normal marrow is studied cytogenetically at different times following aspiration, and that the major changes occur during the first 8 hours. These findings have importance for how cytogenetic studies are performed in leukemia.

Carrier detection and prenatal diagnosis in X linked muscular dystrophy using restriction fragment length polymorphisms

With the aim of offering carrier detection, genetic counselling, and prenatal diagnosis to as many families with Duchenne (DMD) and Becker (BMD) muscular dystrophy as possible, we used available DNA probes to determine the usefulness of the RFLP approach. We report in detail the risks calculated using Bayesian theory and combining pedigree and creatine kinase (CK) data with information derived from the RFLP studies. To date we have analysed members of 28 DMD families (10 familial, 18 sporadic) and six BMD families (four familial, two sporadic) with the closely linked pERT probes 87-1, 87-8, and 87-15 (DXS164). In addition, key members of all families were analysed with probes D2 (DXS43), C7 (DXS28), 754 (DXS84), and L1 X 28 (DXS7). Of the 97 females at risk of being carriers (not including 26 obligate carriers), the RFLP results were compatible with carriership in 22 and not in 51. In 24 females (including 17 mothers of sporadic cases), no information regarding carriership was derived from the RFLP studies. There was no disagreement between pedigree information, clearly raised CK values, and DNA studies. Of 52 obligate or possible carriers under the age of 45, prenatal diagnosis is possible in 49. Prenatal diagnostic RFLP studies have so far been done in three women. In one sporadic DMD family and one BMD family with three affected males the probands showed a deletion involving the three pERT87 subclones used. Experience derived from these families indicates that in our society genetic counselling in X linked muscular dystrophy is received with approval or even enthusiasm in spite of the 5% error estimate that we have quoted for pERT87 derived results.

The use and misuse of sex chromatin screening for 'gender identification' of female athletes

According to the rules of sports organizations such as the International Olympic Committee, competitors registered as females must undergo a "gender verification" test that consists of screening with sex chromatin, followed by further tests in those with an abnormal or inconclusive result. The aims of the gender verification test have not been published but presumably they are to exclude from women's sports events males or other individuals whose muscle strength or body build gives them an unfair advantage over their competitors. It is shown herein that the sex chromatin screening method reveals only a small proportion of such individuals. Moreover, women with certain congenital chromosome abnormalities and other abnormal conditions without increased muscle strength are found to have "abnormal" sex chromatin. Thus, the present screening method is both inaccurate and discriminatory. It is proposed that the aims of gender identification should be defined and methods chosen that achieve the desired result.

Chromosome Y-specific DNA is transferred to the short arm of X chromosome in human XX males

Y-chromosomal DNA is present in the genomes of most human XX males. In these cases, maleness is probably due to the presence of the Y-encoded testis-determining factor (TDF). By means of in situ hybridization of a probe (pDP105) detecting Y-specific DNA to metaphases from three XX males, it was demonstrated that the Y DNA is located on the tip of the short arm of an X chromosome. This finding supports the hypothesis that XX maleness is frequently the result of transfer of Y DNA, including TDF, to a paternally derived X chromosome.

Analysis of deletions in DNA from patients with Becker and Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic disorder for which the biochemical defect is as yet unknown. Recently, two cloned segments of human X-chromosome DNA have been described which detect structural alterations within or near the genetic locus responsible for the disorder. Both of these cloned segments were described as tightly linked to the locus and were capable of detecting deletions in the DNA of boys affected with DMD. In an attempt to determine more precisely the occurrence of these deletions within a large population of DMD patients and the accuracy of one of the segments, DXS164 (pERT87), in determining the inheritance of the DMD X chromosome, the subclones 1, 8 and 15 were made available to many investigators throughout the world. Here we describe the combined results of more than 20 research laboratories with respect to the occurrence of deletions at the DXS164 locus in DNA samples isolated from patients with DMD and Becker muscular dystrophy (BMD). The results indicate that the DXS164 locus apparently recombines with DMD 5% of the time, but is probably located between independent sites of mutation which yield DMD. The breakpoints of some deletions are delineated within the DXS164 locus, and it is evident that the deletions at the DMD locus are frequent and extremely large.

The proportion of mitoses in different cell lineages changes during short-term culture of normal human bone marrow

To determine the hematopoietic cell lineage of mitotic cells in human bone marrow on direct examination and after 24-hour culture, marrow mitoses from four healthy individuals were studied, using a new technique that allows analysis of karyotypes in cells whose cell membrane and cytoplasm have been preserved. Mitoses were identified as being of erythroid lineage by immunofluorescent staining for surface glycophorin A and as being of granulocytic lineage by cytoplasmic staining for Sudan black B. On direct marrow examination without prior culture, the great majority of mitoses (74% to 90%) were of erythroid lineage; only a few (0% to 10%) were granulocytic. After 24-hour culture, the percentage of erythroid mitoses (15% to 40%) decreased, while the percentage of granulocytic mitoses (58% to 87%) increased strikingly. These data indicate that mitotic cells of different hematopoietic cell lineages predominate in marrow at different culture times and offer a plausible explanation for the high frequency of normal karyotypes in acute myeloid leukemia after direct marrow cytogenetic evaluation.

Trisomy 12 in B cells of patients with B-cell chronic lymphocytic leukemia

Trisomy 12 is the most frequently reported chromosome abnormality in patients with B-cell chronic lymphocytic leukemia, but only normal karyotypes are found in one third of patients with that disorder. Moreover, samples from patients with trisomy 12 also have many normal metaphases. To identify immunologically the cells in which both the trisomy 12 and the normal karyotypes occur, we studied two patients with B-cell chronic lymphocytic leukemia--one whose neoplastic cells demonstrated lambda light-chain clonality and one whose cells had kappa light-chain clonality. We used a recently developed cytogenetic method that allows simultaneous analysis of cell morphology, immunologic phenotype, and karyotype in the same mitotic cell. In cultures of blood cells stimulated with pokeweed mitogen and tetradecanoylphorbol acetate, all the mitotic cells with either the lambda or the kappa immunoglobulin had trisomy 12, whereas all the cells that lacked these light chains or that had T-cell markers (OKT8 or OKT4) had normal karyotypes. These results show that trisomy 12 in B-cell chronic lymphocytic leukemia occurs in the neoplastic B cells, but not in the T cells, and they thus provide an explanation for the common finding of mitoses with normal karyotypes in patients with B-cell chronic lymphocytic leukemia.

The origin of 45,X males

Maleness in association with the karyotype 45,X is a very rare and hitherto unexplained condition previously described in only four or five patients. This study was carried out to determine whether such males might actually possess Y-chromosomal material. Of the two 45,X males studied, one was found to be a low-grade mosaic with a 46,XY karyotype in less than 3% of fibroblasts; all lymphocytes karyotyped were 45,X. Fibroblast DNA from this individual was found to contain Y-specific repeated sequences in 1%-3% the amount observed in the father, consistent with mosaicism for a 46,XY cell line. No Y-specific repeated sequences were detected in the other patient, in whom all mitoses were 45,X. In neither patient were there detectable amounts of any of the single-copy Y-specific DNA sequences for which we tested. Studies of Xg blood groups and of X-linked restriction fragment length polymorphisms indicated that the single X chromosome was of maternal origin in both 45,X male probands. In contrast to the situation in XX males, we can exclude paternal X-Y interchange as the etiology in the cases described here. Our findings are compatible with mosaicism being the explanation of at least some "45,X" males.

A deletion map of the human Y chromosome based on DNA hybridization

The genomes of 27 individuals (19 XX males, two XX hermaphrodites, and six persons with microscopically detectable anomalies of the Y chromosome) were analyzed by hybridization for the presence or absence of 23 Y-specific DNA restriction fragments. Y-specific DNA was detected in 12 of the XX males and in all six individuals with microscopic anomalies. The results are consistent with each of these individuals carrying a single contiguous portion of the Y chromosome; that is, the results suggest a deletion map of the Y chromosome, in which each of the 23 Y-specific restriction fragments tested can be assigned to one of seven intervals. We have established the polarity of this map with respect to the long and short arms of the Y chromosome. On the short arm, there is a large cluster of sequences homologous to the X chromosome. The testis determinant(s) map to one of the intervals on the short arm.

Chromosomal abnormalities identify high-risk and low-risk patients with acute lymphoblastic leukemia

The importance of banded chromosome analyses in predicting long-term outcome in acute lymphoblastic leukemia (ALL) was evaluated in this follow-up study of 329 patients from the Third International Workshop on Chromosomes in Leukemia. Patients were divided into ten groups according to pretreatment karyotype: no abnormalities, one of the following structural abnormalities [the Philadelphia chromosome, translocations involving 8q24,t(4;11), 14q+, 6q-] or, in the remaining cases, modal number [less than 46, 46, 47 to 50, greater than 50]. Achievement and duration of complete remission (CR) and survival differed among chromosome groups (P less than .0001). Karyotype was an independent prognostic factor for duration of first CR and survival, even when age, initial leukocyte count (WBC), French-American-British (FAB) type, and immunologic phenotype were considered. Among adults, prolonged remission and survival were uncommon in all chromosome groups. Only in the normal karyotype group was median survival even two years. Among children, striking differences in long-term remission and survival were seen depending upon karyotype. Children in the greater than 50 group did best, with 70% remaining in first CR for a median duration in excess of five years. Children in the 47-50, 6q-, and normal karyotype groups also had prolonged survivals. In contrast, certain translocations [t(9;22)(q34;q11), t(4;11)(q21;q14-23), t(8;14)(q24;q32)] identified children who had short survivals, even in the presence of favorable prognostic factors including a low WBC, L1 morphology, and non-T, non-B immunologic phenotype. We conclude that chromosome analysis is required at diagnosis in patients with ALL, and that children with these specific translocations should be managed as having high-risk ALL.

t(1;3)(p36;q21) in acute nonlymphocytic leukemia: a new cytogenetic-clinicopathologic association

A number of specific chromosomal abnormalities have been associated with distinctive clinical and/or morphological subtypes of acute nonlymphocytic leukemia (ANLL) in recent years. We have studied three patients with ANLL and t(1;3)(p36;q21). Each had weakness as their major complaint, a moderately severe anemia and, for ANLL, a relatively high platelet count. All three demonstrated abnormalities of the megakaryocytic, erythroid and granulocytic lineages. Most striking was the dysmegakaryocytopoiesis. The blasts in all three patients showed relatively few azurophilic granules, one to four prominent nucleoli, and rare peroxidase positivity. No patient had Auer rods. No patient responded to standard chemotherapy regimens. The data suggest that t(1;3)(p36;q21) identifies a new cytogenetic-clinicopathologic subtype of ANLL.

Acute myelogenous leukaemia with c-myc amplification and double minute chromosomes

Cytogenetic analysis of bone-marrow cells from a woman with preleukaemia showed numerous mitoses with trisomy 4 and double minute chromosomes. These abnormalities were later seen in blood cells during subsequent acute myeloid leukaemia (AML). Complete remission was achieved with three courses of doxorubicin, cytosine arabinoside, and prednisone. A further clonal abnormality, trisomy 6, was seen in leukaemic cells after the first relapse. Analyses of total DNA from the peripheral-blood cells during relapse showed that the c-myc oncogene was amplified about 30-fold in the leukaemic cells. The N-myc, c-mos, and c-myb oncogenes showed only single-copy signals. On average about two copies of c-myc resided on each dmin chromosome. The finding of amplification of a cellular oncogene (c-myc) in fresh AML cells containing double minute chromosomes suggests that clonal evolution of some leukaemia cell populations may involve selection for increased dosage of oncogenes.

Pseudoautosomal DNA sequences in the pairing region of the human sex chromosomes

A DNA probe from a human Y chromosome-derived cosmid detects a single-copy genomic DNA fragment which can appear in different allelic forms shared by both sex chromosomes. Variants at this DNA locus show an autosomal pattern of inheritance, undergo recombination with sexual phenotype and can therefore be described as 'pseudoautosomal'. Another probe from the same cosmid detects a sequence repeated 15-20 times per haploid genome. These repeats also appear pseudoautosomal and map exclusively to the short-arm terminal region of each sex chromosome.

Norrie disease caused by a gene deletion allowing carrier detection and prenatal diagnosis

Carrier determination and prenatal diagnosis in Norrie disease (ND) has so far not been reported. We describe a kindred with 4 members affected by ND in which a deletion comprising gene locus DXS7 on the short arm of the X chromosome defined by probe L1.28 causes the disorder. This allowed us to predict via chorion villus biopsy that a male foetus of a carrier woman is unaffected.

Chromosome Y-specific DNA in related human XX males

Human 'XX males' are sterile males whose chromosomes seem to be those of a normal female. About 1 in 20,000 males has a 46, XX karyotype, and most cases are sporadic, that is, they are without familial clustering. It has long been argued that maleness in XX males may result from the undetected presence of a small, testis-determining fragment of the Y chromosome, and there is strong evidence for this in sporadically occurring XX males. Indeed, the genomes of three of four sporadic XX males tested were found to contain certain Y-specific DNA sequences. A pedigree in which three XX males occur has been interpreted as being consistent with autosomal recessive inheritance of maleness, and it has been argued that the basis of XX maleness in this family is fundamentally different from that in the sporadic cases. However, we report here that these related XX males, like the sporadic cases, contain portions of the Y chromosome. The portion of the Y chromosome present in one of the three XX males differs from that present in the other two.

Mapping DNA sequences in a human X-chromosome deletion which extends across the region of the Duchenne muscular dystrophy mutation

A somatic cell hybrid has been constructed and characterized using fibroblasts from a phenotypically normal woman who possesses an X chromosome with an interstitial deletion of the short arm. High-resolution banding indicates that the deleted segment is either Xp22.13-p11.4 or Xp22.11-p11.23. Southern blot hybridization to previously mapped DNA sequences confirms that the missing segment of the X chromosome is a deletion and not an interstitial translocation and supports the cytogenetic interpretation that the deletion extends proximal of Xp11.3 and therefore probably comprises Xp22.11-p11.23. Three further DNA sequences have been localized to the region of the deleted segment. The following order has been assigned to the seven probes used: Xpter-RC8-pXUT22-(OA1,C7,M2C)-L1.28-RD6 -Xcen.

Segregation and fertility analysis in an autosomal reciprocal translocation, t(1;8)(q41;q23.1)

We report a previously undescribed autosomal reciprocal translocation, t(1;8)(q41;q23.1). It segregates in three families whose common origin lies at least 11 generations back. No examples of unbalanced karyotypes were encountered. Moreover, there was no circumstantial evidence that such live births had occurred during earlier generations. Couples in which one spouse was a translocation carrier were compared to related couples with normal karyotypes. The 15 carrier families had significantly more spontaneous abortions (32%) than the 22 normal couples (10%), irrespective of the sex of the carrier parent. However, the mean number of children was equal in both groups (2.0 and 2.4). Carrier families produced 17 children with a balanced translocation and seven with a normal karyotype. This deviates significantly (P = .04) from the expected 1:1 ratio. We conclude that this malsegregation helps to maintain the translocation in the population. These results show that empirically derived 1:1 segregation ratios previously reported in series that combine many different translocations do not apply to all individual translocations.

t(11;19)(q23;p11) in a child with acute T-cell leukemia

A translocation, t(11;19)(q23;p11), is reported in a child with T-cell leukemia. Our case indicates that the t(11;19) may not be restricted to the monocytic leukemias, as earlier reported, but may occur in other malignancies.

A method for simultaneous study of the karyotype, morphology, and immunologic phenotype of mitotic cells in hematologic malignancies

A major problem in the cytogenetic analysis of hematologic neoplasms has been an inability to identify the cell from which the chromosomes were obtained. We describe a procedure that allows simultaneous analysis of karyotype and cell cytology in mitotic cells. The method differs from conventional cytogenetic analysis in that after mild hypotonic treatment, the cells are cytocentrifuged onto glass slides. In mitotic cells, this procedure often results in adequate spread of the chromosomes within the intact cell membrane. The cytoplasmic structure also remains intact, so that cytologic preparations are of good quality. Morphologic and immunologic identification of mitotic cells can be done using routine hematologic stains, such as Giemsa or Sudan black B, and various antisera using immunofluorescence techniques. The chromosomes can be simultaneously analyzed either without banding on slides stained with Giemsa or with Q-banding on slides stained with immunofluorescence techniques. Identification of numerical and structural karyotype aberrations thus is possible in morphologically identified cells.

Aberrant expression of an amplified c-myb oncogene in two cell lines from a colon carcinoma

Two cell lines (COLO 201 and COLO 205) derived independently from a single adenocarcinoma of the human colon each harbored an approximately 10-fold amplification of the cellular oncogene c-myb and a proportional abundance of the 4-kilobase mRNA derived from c-myb. By contrast, expression of c-myb could not be detected in cells from a variety of other solid tumors, including other colon carcinomas. Analysis of the amplified DNA with restriction endonucleases failed to reveal any topographical abnormalities within c-myb. Neither COLO 201 nor COLO 205 carry the double minute chromosomes and homogeneously staining regions of chromosomes that frequently serve as karyotypic signatures of amplified DNA. Instead, amplified c-myb is carried on what appear to be disomic or trisomic copies of the same anomalous marker chromosome that is characteristic of both COLO 201 and COLO 205. The karyological origin of this abnormal chromosome is not presently apparent. Our findings show c-myb expression by cells outside of the hemopoietic lineage, raise the possibility that amplification and/or ectopic expression of c-myb may have contributed to the genesis of the tumor from which the cells of COLO 201 and COLO 205 arose, and suggest that amplification of cellular oncogenes may be a more common factor in tumorigenesis than might have been suspected from available karyological data.

Abnormalities of chromosome 13 in myelofibrosis

19 patients with myelofibrosis, primary or following polycythaemia vera were studied cytogenetically. Bone marrow cells, unstimulated and stimulated cells from peripheral blood were investigated. 7 patients were found to have clonal aberrations, 3 of whom had a structural rearrangement of chromosome 13. In 2 additional cases single mitoses with 13q- were found. Reviewing the files on patients previously studied in our laboratory, 2 more patients with 13q- markers were noted. Both had had haematologic disorders in which fibrosis of the bone marrow can be found, but this feature could not be evaluated retrospectively, because no biopsies had been taken. Our data and those found in the literature suggest that rearrangements of 13q12----q22 are often associated with myelofibrosis, both in its primary form or following polycythaemia vera.

The parental origin of X chromosomes in XX males determined using restriction fragment length polymorphisms

The inheritance of several X-linked restriction fragment length polymorphisms ( RFLPs ) is examined in seven 46,XX males and their immediate relatives. The XX males are shown to have inherited a paternal and a maternal RFLP allele in each of the five (of seven) families in which these X-linked markers are informative. In the other two families, a maternal X-chromosomal contribution is demonstrated, but a paternal contribution cannot be determined. We conclude that most, if not all, XX males inherit one paternal and one maternal X chromosome. A segment of single-copy DNA specific to the short arm of the Y chromosome is found to be absent from the genomes of eight XX males. In one of these XX males, an Xp-Yp translocation had previously been inferred from chromosome-banding studies. Our findings argue against mosaicism involving a Y-containing cell line in the XX males examined here, but they do not exclude an X-Y (or Y-autosome) translocation during paternal meiosis. If such a translocation has occurred, the translocation product received by the XX males does not include the Yp-specific sequence tested here.

Critical chromosome rearrangement in acute promyelocytic leukemia

We report here a patient with acute promyelocytic leukemia (APL) who has two normal chromosomes #15 but a structurally abnormal chromosome #17. This case indicates that the critical point of rearrangement in APL is not necessarily in chromosome #15 but may, alternatively, be in chromosome #17.

Fourth International Workshop on Chromosomes in Leukemia 1982: Clinical significance of chromosomal abnormalities in acute nonlymphoblastic leukemia

Seven hundred sixteen newly diagnosed patients were studied, to determine the clinical significance of chromosome analysis in ANLL. Karyotypes were classified in two ways. Cases were grouped into three categories, based on the presence of normal and abnormal metaphases. Cases were grouped into 12 categories based on more specific chromosome abnormalities (modified Chicago Classification). Both methods of classifying karyotypes, but especially the Chicago Classification, resulted in groups of patients with de novo ANLL with significantly different presenting clinical and hematologic features, including FAB type, leukocyte count, percent peripheral myeloblasts, platelet count, and DIC. Among patients with de novo ANLL, karyotypes, when classified according to the Chicago Classification, significantly correlated with frequency of initial complete remission and survival; the presence of normal and abnormal metaphases correlated with duration of first remission and survival. Among 305 intensively treated patients, the Chicago Classification also correlated with duration of first remission. Although both ways of classifying karyotype correlated with survival, even when other major risk factors in ANLL were considered, only the Chicago Classification was an independent prognostic factor among the intensively treated patients.

Genetic evidence of X-Y interchange in a human XX male

Of the hypotheses put forward to explain why occasional individuals with two X chromosomes are nonetheless male, the one that has attracted most attention is the possibility that one of the X chromosomes has obtained a small piece of Y chromosome which is sufficient to produce 'maleness'. This hypothesis was based primarily on the observation that in two families with XX males both fathers were Xg(a+) and both probands Xg(a-). (Xg shows X-linked dominant inheritance.) This theory holds that an anomalous X-Y interchange at meiosis in the father resulted in the paternal X chromosome's losing the Xg gene and acquiring a male-determining gene from the Y chromosome. While, for example, the frequencies of Xg phenotypes among XX males and the cytogenetic observation of a structural abnormality in one X are compatible with this hypothesis, direct evidence of it is lacking. Here we describe an XX male who expresses his father's allele for 12E7, a Y-linked marker, but fails to express his father's allele for Xg, an X-linked marker. These findings strongly suggest that anomalous X-Y interchange occurred in this case and perhaps in that of many other XX males. We suggest that a male-determining gene on the Y has also been translocated to the X and caused maleness in the proband. These results are discussed in the light of current models of X-Y chromosomal homology.

Protein A radio-assay of H-Y antigen on human leukocytes using mouse and rat antisera and monoclonal antibodies

The presence of H-Y antigen on human leukocytes was investigated using a protein A radio-assay. H-Y antigen could be demonstrated on male cells using either conventional H-Y antisera produced in mice and rats, or monoclonal H-Y antibodies. With mouse antiserum and IgG-type monoclonal antibody the reaction was male-specific using a single antibody. The reaction obtained with rat antiserum was enhanced by the application of a second antibody (rabbit anti-mouse IgG). This technique provides a rapid, simple, objective, and semiquantitative method for the determination of cellular H-Y antigen, the results being expressed as radioactivity bound to the test cells and thus being independent of human observation. It requires only 10-20 ml of blood and small quantities of antiserum or antibody.

Lambda Ig constant region genes are translocated to chromosome 8 in Burkitt's lymphoma with t(8;22)

By in situ hybridization of normal human chromosomes with a cloned genomic probe specific for the constant region of the lambda immunoglobulin genes, band 22q11 was preferentially labelled. In two cell lines with t(8;22) derived from Burkitt's lymphoma a strong signal was noted on the 8q+ chromosome derivative, indicating that the constant region of the lambda Ig gene cluster was translocated from chromosome 22 to chromosome 8. In addition, the signal observed on the 22q- derivative chromosome was stronger than the background in one of the two cell lines tested, but not in the other. The implications are that the break point in chromosome 22 in some cases lies within the Ig gene itself or between clusters of such genes, and that different cases have different break points.

Human type I procollagen genes are located on different chromosomes

A recombinant plasmid containing sequences complementary to human pro-alpha l(I) collagen mRNA was used for the chromosomal assignment of the pro-alpha l(I) collagen gene. Restriction endonuclease analysis of DNA from mouse-human and Chinese hamster-human somatic cell hybrids revealed cosegregation with human chromosome 17. Hybrids containing derivative chromosomes with a t(2;17)(q14;q21) translocation showed cosegregation of the pro-alpha l(I) gene with the segment 17q21 leads to qter. In situ hybridization on human metaphasic chromosomes confirmed this conclusion.

Different patterns of X chromosome inactivity in lymphocytes and fibroblasts of a human balanced X;autosome translocation

In lymphocytes of a human female carrier of a balanced X;3 translocation, 46,X,t(X;3)(q28;q21), late replication of the structurally normal X chromosome only was previously described (de la Chapelle and Schröder 1973). We have now confirmed this finding using a fresh blood sample. Examining the chromosomes of this individual in fibroblasts we observed that either the normal X or the Xq+ chromosome could replicate late and show inactivity after fusion with heteroploid mouse cells. The replication patterns of chromosomes in human X;autosome translocations have so far almost exclusively been analyzed in lymphocytes. Our findings stress that results based on these cells are not representative for all cell types.

Abnormalities of chromosome No. 17 in myeloproliferative disorders

In routine analyses, abnormalities of chromosome No. 17 were found in the bone marrow cells of 28 patients with Ph1-positive and three patients with Ph1-negative chronic myeloid leukemia (CML), 4 patients with acute nonlymphocytic leukemia (ANLL), and 4 patients with preleukemia. With three exceptions, all patients were in the blastic (CML) or the terminal phase. In 28 patients, the aberrant chromosome No. 17 arose by clonal evolution from the karyotype found at diagnosis or before the terminal phase. The abnormalities encountered were an isochromosome for the long arm, i(17q), (26 cases), translocations involving No. 17 (12 cases), trisomy 17 (three cases), and ring 17 (one case). In 35 patients, there was an unbalanced structural aberration of at least one of the No. 17 chromosomes. In every case (35/35), detailed analysis of the structurally abnormal No. 17 revealed loss of the distal part of the short arm (or possibly most of the short arm). Gain of the long arm (or at least its proximal part) was also common, but not invariably present (26/35). It is suggested that loss of 17p is a highly nonrandom event related to blastic crisis in CML and the terminal phase in other myeloid leukemias.

Defective neutrophil migration in monosomy-7

The migration in vitro of neutrophils from six patients with monosomy-7 or partial deletion of the long arm of chromosome 7 was studied by two methods: the Millipore filter assay and the migration under agarose assay. Four of the patients had preleukemia, one had subacute myelomonocytic leukemia, and one polycythemia vera. In four patients, chemotaxis (migration towards a higher concentration of chemoattractant) and chemokinesis (stimulated migration without a gradient) were shown to be defective by both methods. In the remaining two patients, this defect could be demonstrated only by the Millipore filter assay or by the agarose assay. Under agarose, random locomotion (no chemoattractant present) of the patients' neutrophils was less than that of the control subjects in four patients, whereas no clear difference could be shown by the Millipore filter method. This study demonstrates that the previously described defect of neutrophil migration in monosomy-7 involves not only chemotaxis but all stimulated migration and, at least in some patients, random locomotion as well. Defective migration in two patients with an apparently terminal deletion of the long arm of one chromosome 7 indicates that the distal half of 7q carries genetic material important for neutrophil locomotion.

The 5q- chromosome in preleukaemia and acute leukaemia

13 patients with the 5q- chromosome are described. In 6 patients the 5q- chromosome was the sole aberration. 10 patients had preleukaemia, 1 a preleukaemia-like syndrome after treatment of polycythaemia vera, a 2 acute myeloid leukaemia. The prognosis was especially poor in terms of survival in preleukaemic patients with 3 or more affected chromosomes: none of these 6 patients survived for more than 6 months. In 4 patients the haematological picture resembled 'the 5q- syndrome'. In the long arm of chromosome No 5 deletions of 3 different kinds were detected. They were named according to the size of the 5q- marker: the short type (10 patients), the intermediate type (1 patient) and the long type (2 patients). There was no clear correlation between the clinical picture and the type of deletion. While the break points cannot always be exactly defined, our data and those reviewed from the literature suggest that the loss of a segment of regions 5q2 or 5q3 is common to all or most deletions.

A deletion in chromosome 22 can cause DiGeorge syndrome

An association between DiGeorge's syndrome and an unbalanced chromosomal rearrangement leading to trisomy 20pter leads to 20q11 and monosomy 22pter leads to 22q11 was found in four individuals belongings to one family. These and other data from the literature are interpreted to suggest that DiGeorge's syndrome can be caused by deletion of a gene located in chromosome 22, probably in band 22q11.

Chromosome studies in acute lymphoblastic leukaemia (ALL)

Chromosome banding studies of the bone marrow were performed in 35 adult (greater than 14 years) patients with acute lymphoblastic leukaemia (ALL). Surface marker analysis was done in 24 of these and revealed 4 B-ALL, 5 T-ALL and 15 non-T non-B ALL. Most patients were studied at diagnosis before any treatment. A clonal karyotypic abnormality was found in 16 patients (46 %) initially. A Philadelphia chromosome was found in 3 patients, all belonging to the non-T non-B group. 5 patients, who all had blast cells with morphologic characteristics of Burkitt type L, were found to have bone marrow cells with a 14q + marker chromosome. In at least 4 cases this was due to a t(8;14). The cytogenetic findings showed some correlation to the ALL subgroup, but not to the response to treatment or the prognosis.