Sister chromatid exchanges induced by nitrogen mustard in Fanconi's anemia. Application to the detection of heterozygotes and interpretation of the results

Nitrogen mustard-induced SCE were studied on Fanconi's anemia (FA) patients, FA parents, and control lymphocyte cultures. When low doses of nitrogen mustard were added at the time cultures were initiated, a distinction could be made between FA heterozygotes and controls. In FA heterozygotes increase of SCE levels higher than that observed in controls was found, thus allowing the recognition of heterozygotes. FA cells appeared to be more sensitive to nitrogen mustard than FA heterozygous and control cells. The data argues in favor of an excision-repair defect, and is discussed in the light of possible repair and SCE production mechanisms.     

Sister chromatid exchange in malignant lymphomas

Sister chromatid exchange (SCE) was evaluated in peripheral lymphocytes from 20 untreated patients with malignant lymphomas: 6 with Hodgkin's disease (HD), 14 with non-Hodgkin lymphoma (NHL), and 5 with lymphadenitis. The mean SCE frequency (+/- SE) was: 11.2 +/- 0.6, 11.0 +/- 0.6, and 7.2 +/- 0.3 for HD, NHL, and lymphadenitis patients, respectively, and 8.7 +/- 0.2 for the control group. No differences in SCE score were observed in HD and NHL. These results allowed us to consider both groups (HD and NHL) as a single neoplastic population (mean +/- SE, 11.0 +/- 0.4). No significant differences were found between the lymphadenitis and control groups. On the other hand, significantly higher SCE scores were seen in neoplastic populations than in the control and lymphadenitis groups (p less than 0.001 and p less than 0.01, respectively). When SCE was compared by chromosome number and group between neoplastic patients and controls, a higher SCE frequency was observed in chromosomes #1, #2, #3, and B, C + X, E, F chromosome groups than in controls. SCE levels were significantly higher in lymphoma patients in all chromosome numbers and groups mentioned than in patients with lymphadenitis. It is suggested that the high SCE rate in the malignant lymphoma population is possibly related to an increased chromosomal instability.     

Chromosome studies in polycythemia vera patients

One hundred thirty-five polycythemia vera (PV) patients (30 untreated by chemotherapy and 105 treated) were studied cytogentically. The incidence of clonal chromosomal abnormalities was 20.7% (28 patients in nonleukemic phase). The incidence of 20q? was 3.7% (5 patients). The presence of cytogenetically abnormal clones did not allow prediction of the evolution of the disease. In a few cases, abnormal clones disappeared at the time of later studies. Although nonrandom, the majority of clonal chromosomal abnormalities are believed to be secondary events in PV patients.     

Cytogenetic studies on acute nonlymphocytic leukemias following polycythemia vera

Chromosome studies were performed on 15 patients suffering from acute nonlymphocytic leukemia (ANLL) and in one patient in a preleukemic state following polycythemia vera (PV). Clonal chromosome abnormalities that were present in all cases were clearly nonrandom and involved chromosomes #1, #5, #7, #8, #9, #11, and #21. A subdivision of ANLL into two categories occurring in the course of PV is proposed from the clinical, hematologic, and cytogenetic data: one resembling de novo ANLL with rapid initial evolution, easy classification into one group of the FAB nomenclature, and simple chromosome abnormalities; the other resembling induced leukemia, often with more progressive initial evolution, difficulty or impossibility of classification into one group of the FAB nomenclature, and complex chromosome abnormalities. The consequences for the commitment level of progenitor cell from which the leukemic clones originate are discussed.     

Y chromosome loss in leukemias

Four cases of leukemia with a missing Y cell line are reported: one of chronic myeloid leukemia in blastic crisis; one of polycythemia vera terminating in acute myeloblastic leukemia, where the missing Y was observed prior to leukemia and was associated with other chromosome abnormalities in the leukemic phase; one of acute myelomonocytic leukemia; and one acute lymphocytic leukemia with, respectively, partial and complete reappearance of the Y chromosome on leukemia remission. The possible significance of the loss of the Y in leukemic cells is discussed.     

t(15;17) in a promyelocytic form of chronic myeloid leukemia blastic crisis

Two simultaneous translocations, t(15;17) and t(9;22), have been observed in a chronic myelogenous leukemia patient with acute promyelocytic blastic crisis. After remission obtention only karyotypes with t(9;22) were present. The occurrence of the two translocations in the same cell argues in favor of the specificity of t(15;17) versus acute promyelocytic differentiation.     

Bone marrow graft of a Fanconi's anemia patient. Cytogenetic study

Lymphocyte chromosome studies before and after allogenic graft of a Fanconi's anemia (FA) patient showed that chromosome breakage disappeared following grafting. The fact that this condition was maintained up to 36 months after grafting demonstrates that the defect responsible for chromosome breakage lies in the FA cell itself.     

Peliosis-like ultrastructural changes of the hepatic sinusoids in human chronic hypervitaminosis A: Report of three cases

In addition to hypertrophy of Ito cells and perisinusoidal fibrosis, previously unrecognized ultrastructural abnormalities of the hepatic sinusoids were observed in three patients with chronic hypervitaminosis A: 1) large areas of communication between the sinusoidal lumina and the perisinusoidal spaces, allowing extravasation of blood cells; 2) marked dilation of the perisinusoidal spaces; and 3) swelling and clarification of endothelial cells. Most of these changes, along with some other sinusoidal barrier alterations previously reported in chronic hypervitaminosis A (i.e., bleb formation on the sinusoidal membrane of the hepatocytes and the presence of multiple cellular layers lining the sinusoids), are strikingly similar to those observed in peliosis hepatis. The present findings suggest that sinusoidal barrier abnormalities might constitute a major event in the pathophysiology of vitamin A-induced liver injury as well as of peliosis hepatis.     

C-banding studies in various blood disorders

A C-banding pattern study has been performed on 70 patients having Philadelphia chromosome-positive chronic myeloid leukemia (CML), 35 with polycythemia vera, 21 with myeloid metaplasias, 40 with acute myeloblastic leukemia (AML) as well as on 70 controls. The length of the C blocks were classified into five levels by comparison with the short arm of chromosome 16, using Patil and Lubs proposals. A significant difference in the distribution of C-band levels of chromosome 1 and an excess of asymmetrical pairs were found for CML compared with the controls. An abnormal distribution of chromosome 9 C variants were also found in blood disorder patients compared with the controls. In CML patients a random distribution of C variants between 9q+ and 9 were found. For the chromosome 16 a significant difference was found concerning the intrapair asymmetry distribution in AML compared with controls.     

Nitrogen mustard-induced chromosome breakage: A tool for Fanconi's anemia diagnosis

Chromosome studies were performed on phytohemagglutinin-stimulated lymphocytes from 9 Fanconi's anemia (FA) patients, 6 of their parents, 7 controls, 2 children with aplastic anemia of unknown etiology, and one child with Zinsser-Cole-Engman syndrome. The addition of low doses (0.0085 μg/ml) of nitrogen mustard to cultures dramatically increased the chromosome breakage level in FA, the increase evaluated from means of chromosome anomalies per cell was highly significant (p < 0.001). On the other hand, the means of chromosome anomalies per cell increased greatly only at higher dilutions in all non-FA subjects. The high susceptibility of FA cells to chromosome breakage by nitrogen mustard may be of use as a diagnostic test and might be useful for prenatal detection of the disease.     

Cytogenetic studies on Burkitt's lymphoma cell lines

Cytogenetic findings on 15 new cell lines established from endemic and nonendemic Burkitt's lymphoma are reported. Specific translocations t(8;14) and t(8;22) were found, respectively, in 13 and in 2 of the cell lines. Particular attention has been paid to the additional chromosome abnormalities found in 10 of the 15 cell lines. These anomalies involve the long arm chromosome No. 1 with a relatively high frequency. These additional chromosome anomalies argue in favor of the concept of the existence of primary and secondary chromosome abnormalities in malignancies.     

Immune response induced by a single or several syngeneic monoclonal antiABPC48 antiidiotypic antibodies: no predominant coexpression of ABPC48 idiotopes

BALB/c mice were immunized with monoclonal BALB/c antibodies IDA10, IDA16 and IDA17 raised against the BALB/c ABPC48 myeloma protein. Several procedures of immunization--copolymers with lipopolysaccharide or keyhole limpet hemocyanin, simultaneous or sequential injections of different IDAs--were performed in an attempt to orient the immune response towards the production of ABPC48-like idiotypes. We used a binding assay which identifies two idiotopes on the same molecule to measure the population of antibodies induced in these responses. The expression of ABPC48 cross-reactive idiotypes in immune sera was analyzed. The results show that, with all immunization protocols, immune responses to different monoclonal antiidiotypic antibodies are mostly independent of each other: the coexpression of ABPC48 idiotopes, either private or recurrent on the induced antibodies, is rarely found; it makes it difficult to discriminate by a serological approach between cross-reactive idiotypes and anti-antiidiotypic antibodies. We discuss the interest of combining molecular and serological approaches to identify these two populations of antibodies.     

Cytogenetic studies on African Burkitt's lymphoma cell lines: t(8;14), t(2;8) and t(8;22) translocations

Cytogenetic studies on ten African Epstein-Barr virus (EBV) positive Burkitt's lymphoma (BL) cell lines were performed. The usual translocation t(8;14) (q24;q32) was found in five of them, a deletion del(8) (q24→qter) in another one, while four variants were observed, two of these having a t(2;8) (p12;q24) translocation and two a t(8;22) (q24;q11) translocation. Other chromosome abnormalities were seen in seven of the cell lines, but these varied from one cell line to another. Thus, variant translocations, such as we describe here, are found in endemic BL cases. Two of these variants are identical to those previously identified in BL from nonendemic areas. The common chromosome abnormality of these BL cell lines was a rearrangement of the 8q24 band. The role of this constant cytogenetic change remains to be elucidated.     

Cytogenetic forms of retinoblastoma: their incidence in a survey of 66 patients

Sixty-six retinoblastoma patients were investigated using high resolution banding techniques, sister chromatid exchange (SCE) studies, and esterase-D phenotype determination and dosage. Seven patients (in six families) were found to be carriers of a rearrangement of band 13q14 due to de novo deletions, apparently balanced de novo translocations, or parental insertions. The possible role of submicroscopic parental insertions is suggested to explain transmission of nonchromosomal forms through unaffected carriers.     

Cytogenetic study of 88 cases of refractory anemia

Data obtained on 88 patients with refractory anemia or preleukemia, without previous cytotoxic treatment, showed medullar chromosomal abnormalities in 32%. In 45% of the cases, the disease had progressed to acute nonlymphocytic leukemia. A high frequency of acute transformation (78%) was observed in patients with abnormal clones. These results are different from those of the Second International Workshop on chromosomes in Leukemia. The discrepancies may be related to the difference between the cases selected for submission to the workshop and those of this study. Serial studies on 28 patients with abnormal karyotypes showed that two different populations of patients were investigated: one with a terminal smoldering phase of leukemia and the other with true preleukemic disease. In the latter group, no predictive karyotype evolution was seen.     

Cytogenetic studies in a case of T-cell prolymphocytic leukemia

The authors describe cytogenetic aberrations observed in a case of T prolymphocytic leukemia. C11 deletion (q14) B5 deletion (pter), D14q⁺, E20 trisomy, and two markers are the main anomalies of the complement.     

Variant translocation in Burkitt's lymphoma: 8;22 translocation in a French patient with an Epstein-Barr virus-associated tumor

A variant translocation t(8;22)(q23;q11) has been found in tumor cells from a 19-year-old white man with an Epstein-Barr virus-associated Burkitt's lymphoma (BL). The tumor, which appeared 2 years after the patient had infectious mononucleosis, bore histopathological features characteristic of BL, although only the lymph nodes in the cervical region were involved. This case and some other recent cytogenetic observations of nonendemic BL emphasize the importance of chromosome #8 rearrangement in this B-cell-type lymphoma.     

Catalase determination in various etiologic forms of Wilms' tumor and gonadoblastoma

We have previously mapped the gene coding for catalase to 11p13 by gene dosage analysis. Deletion of this chromosomal region causes aniridia, mental retardation, and predisposition to Wilms' tumor (WT). In the present study, 22 patients with various etiologic forms of WT and/or aniridia were investigated. The catalase (CAT) level and karyotype were examined in order to determine the linkage and the gene ordering on chromosome number 11 of the different loci involved. The CAT concentration was normal in the 19 cases without detectable chromosomal abnormalities.     

Phenotypic spectrum associated with SPECC1L pathogenic variants: new families and critical review of the nosology of Teebi,Opitz GBBB,and Baraitser-Winter syndromes

The SPECC1L protein plays a role in adherens junctions involved in cell adhesion, actin cytoskeleton organization, microtubule stabilization, spindle organization and cytokinesis. It modulates PI3K-AKT signaling and controls cranial neural crest cell delamination during facial morphogenesis. SPECC1L causative variants were first identified in individuals with oblique facial clefts. Recently, causative variants in SPECC1L were reported in a pedigree reported in 1988 as atypical Opitz GBBB syndrome. Six families with SPECC1L variants have been reported thus far. We report here eight further pedigrees with SPECC1L variants, including a three-generation family, and a further individual of a previously published family. We discuss the nosology of Teebi and GBBB, and the syndromes related to SPECC1L variants. Although the phenotype of individuals with SPECC1L mutations shows overlap with Opitz syndrome in its craniofacial anomalies, the canonical laryngeal malformations and male genital anomalies are not observed. Instead, individuals with SPECCL1 variants have branchial fistulae, omphalocele, diaphragmatic hernias, and uterus didelphis. We also point to the clinical overlap of SPECC1L syndrome with mild Baraitser-Winter craniofrontofacial syndrome: they share similar dysmorphic features (wide, short nose with a large tip, cleft lip and palate, blepharoptosis, retrognathia, and craniosynostosis), although intellectual disability, neuronal migration defect, and muscular problems remain largely specific to Baraitser-Winter syndrome. In conclusion, we suggest that patients with pathogenic variants in SPECC1L should not be described as “dominant (or type 2) Opitz GBBB syndrome”, and instead should be referred to as “SPECC1L syndrome” as both disorders show distinctive, non overlapping developmental anomalies beyond facial communalities.