Familial bone marrow monosomy 7. Evidence that the predisposing locus is not on the long arm of chromosome 7.

Loss of expression of a tumor-suppressing gene is an attractive model to explain the cytogenetic and epidemiologic features of cases of myelodysplasia and acute myelogenous leukemia (AML) associated with bone marrow monosomy 7 or partial deletion of the long arm (7q-). We used probes from within the breakpoint region on 7q-chromosomes (7q22-34) that detect restriction fragment length polymorphisms (RFLPs) to investigate three families in which two siblings developed myelodysplasia with monosomy 7. In the first family, probes from the proximal part of this region identified DNA derived from the same maternal chromosome in both leukemias. The RFLPs in these siblings diverged at the more distal J3.11 marker due to a mitotic recombination in one patient, a result that suggested a critical region on 7q proximal to probe J3.11. Detailed RFLP mapping of the implicated region was then performed in two additional unrelated pairs of affected siblings. In these families, DNA derived from different parental chromosome 7s was retained in the leukemic bone marrows of the siblings. We conclude that the familial predisposition to myelodysplasia is not located within a consistently deleted segment on the long arm of chromosome 7. These data provide evidence implicating multiple genetic events in the pathogenesis of myelodysplasia seen in association with bone marrow monosomy 7 or 7q-.

Philadelphia chromosome-positive acute lymphoblastic leukemia cell lines without classical breakpoint cluster region rearrangement.

The Philadelphia (Ph) chromosome translocation which is classically observed in chronic myeloid leukemia (CML) is sporadically found in acute lymphoblastic leukemia (ALL). In CML the translocation breakpoint on chromosome 22 is within the breakpoint cluster region, while in childhood ALL, no detectable change in breakpoint cluster region is routinely observed. In order to investigate the nature of this difference, we have established and characterized two cell lines from a child with Ph positive ALL. The cell lines have retained the cytochemical staining pattern, enzyme activity, monoclonal antibody profile, and immunoglobulin gene rearrangements of the child's malignant cells. The cell lines had the same Ph translocation t(9;22) (q34;q11) as the child's malignant cells along with additional chromosome changes. Southern blot analysis showed that the Ph translocation did not involve the 5.8-kilobase breakpoint cluster region segment characteristically seen in CML. The cell lines reported here will be a valuable resource in ascertaining the biological significance of the Ph translocation seen in ALL.

Monoclonal antibody and enzymatic profiles of human malignant T-lymphoid cells and derived cell lines.

Recently, four distinct cell lines were established from patients whose malignancies had been defined by immunological and biochemical markers. Each patient had a distinct subtype of a T-cell cancer, and each possessed elevated adenosine deaminase and reduced nucleoside phosphorylase activity. Cell lines cultured in vitro possessed the same basic immunophenotype and biochemical enzyme activity as the patients' original malignant cells. In a direct comparison of the immunophenotype of the cell lines and the patients' malignant cells, full concordance existed for 48 of 52 paired antibody tests performed. However, when compared to the corresponding patient's sample, each cell line showed some minor changes in antigen expression or enzyme level. Antigen loss, de novo antigen expression, or elevated adenosine deaminase levels occurred in the cell lines, and these changes were stable on repeated analysis. While there was good general concordance between the patient's cancer and the established cell line, minor biological differences in the cell lines may reflect cellular maturation or subpopulation selection in vitro.

Establishment and characterization of a common acute lymphoblastic leukemia cell line with a deletion of chromosome 3 band q26.

This paper describes the establishment and characterization of a new cell line (SUP-B7) which was established from a child with "common" acute lymphoblastic leukemia. The SUP-B7 cells (and the patient's tumor) have been characterized by cytochemical staining, monoclonal antibodies, enzyme analyses, gene rearrangement studies, and karyotype analysis. The SUP-B7 cells are periodic acid-Schiff positive, common acute lymphoblastic leukemia antigen positive, and terminal deoxynucleotidyl transferase positive, and they lack the Epstein-Barr virus genome. In addition, the SUP-B7 cells lack cytoplasmic and surface immunoglobulins, and the immunoglobulin gene rearrangement studies showed rearranged heavy chain genes with germ line light chain genes. Concordance between the cell line and the patient's tumor was established by the immunoglobulin gene rearrangement studies. Using Southern blot analysis of the DNA from the patient's tumor and the SUP-B7 cells, there was comigration of the bands representing the rearranged immunoglobulin heavy chain gene. In addition, the SUP-B7 cells possess a single chromosome abnormality: del(3)(q26q28), with the chromosome breakpoint at or near the transferrin receptor gene. Since the SUP-B7 cell line is concordant with the patient's malignancy and since these cells possess a single chromosomal abnormality, the SUP-B7 cell line may be a useful tool in determining the biological significance of the chromosome deletion: del(3)(q26q28).

Care of the critically ill child: the bleeding neonate.

Serious bleeding episodes in newborn infants can usually be diagnosed following careful clinical assessment and a few simple laboratory tests. Certain conditions are found almost exclusively in "sick" infants, whereas other coagulation abnormalities occur in otherwise "healthy" neonates. Successful management of hemorrhage necessitates a correct diagnosis which thereby dictates appropirate therapy. In some cases, such as in DIC, successful outcome ultimately depends on correction of the underlying pathophysiology which triggered the coagulation disturbance.

Fatal myocardial infarction following therapy with prothrombin complex concentrates in a young man with hemophilia A.

A fatal myocardial infarction in a 22-year-old man with hemophilia A and a factor VIII inhibitor is described. The catastrophic event occurred while the patient was receiving high doses of unactivated prothrombin complex concentrates. Autopsy examination revealed myocardial hemorrhage with no evidence of coronary artery disease or thrombosis. There also was postmortem evidence of previous myocardial infarctions. This is the fourth documented case of myocardial infarction occurring in a young hemophiliac patient using unactivated prothrombin complex concentrates. It is concluded that utilization of prothrombin complex concentrates in hemophiliac patients must be limited and closely monitored. Therapeutic guidelines are recommended.

Congenital hypoplastic (Diamond-Blackfan) anemia in seven members of one kindred.

Congenital hypoplastic (Diamond-Blackfan) anemia is a rare macrocytic anemia, generally presenting during infancy or childhood. The condition usually occurs sporadically or in a pattern consistent with autosomal recessive inheritance, although autosomal dominant transmission has been proposed in some kindreds. We report the largest known kindred of congenital hypoplastic anemia, with at least 7 affected individuals over 3 generations, and propose that studies of this kindred may be useful for identifying the mechanism by which their genetic abnormality results in congenital hypoplastic anemia. Erythropoietic investigations on relatives show no inhibitors of erythropoiesis in serum, T-lymphocytes, or macrophages. Their erythroid progenitor cells (CFU-E and BFU-E) were generally quantitatively normal, and were capable of rapid proliferation, as judged by cell-cycle shortening. However, their erythroid progenitors displayed a relative insensitivity to recombinant erythropoietin, and produced relatively few normoblasts per erythroid progenitor cell. We propose that these and subsequent studies may be helpful in selecting candidate genes responsible for the molecular defect in this kindred.

Bilateral microtia and cleft palate in cousins with Diamond-Blackfan anemia.

We report on maternal first cousins with bilateral microtia, micrognathia, cleft palate and hematologic findings of Diamond-Blackfan anemia (DBA). The similarity of findings shared between our cases and a female reported by Hasan and Inoue [1993] suggests that this is a distinctive syndrome, rather than a chance association. DBA is a heterogeneous disorder, caused in about 25% of cases by heterozygous mutations in the RPS19 gene (DBA1). Mutation analysis in our cases did not show an RPS19 mutation, and 2 alleles were present in each. Segregation analysis for DBA1 on chromosome 19 and DBA2 on 8p23 was not consistent with linkage. We conclude that this syndrome of microtia, cleft palate and DBA is not allelic to known DBA loci.

Microcytosis associated with sickle cell anemia.

Sickle cell (Hb SS) anemia is considered a normochromic-normocytic hemolytic disorder. In 53 patients with Hb SS (mean reticulocyte values 16.8%), the authors observed that mean corpuscular hemoglobin (MCH) was 29.8 +/- 2.4 mu microgram and mean corpuscular hemoglobin (MCV) was 88.1 +/- 6.8 cu micrometers. In contrast, patients in a comparable hemolytic-disease group unrelated to hemoglobinopathies (mean reticulocyte count = 15.7%) had a higher MCH (33.0 +/- 1.8 mu microgram) and larger MCV (97 +/- 5.3 cu micrometers). These data indicate that Hb SS disease is associated with "relative microcytosis," presumably a consequence of reduced hemoglobin production.

Diagnosis and management of red cell aplasia in children.

The vast majority of pediatric RBC hypoplastic anemias are accounted for by red blood cell aplasia associated with chronic hemolysis, Diamond-Blackfan anemia, and transient erythroblastopenia of childhood. However, other causes of hypoplastic anemia occur in children, and some of these are similar to what is seen in adult RBC aplasia. For example, it has been reported that a 5-year-old girl with an aregenerative anemia had a thymoma and later developed pancytopenia. RBC aplasia also has been seen in children receiving anticonvulsant drug therapy, children recovering from severe protein malnutrition, children with hepatitis, and in children with leukemia during maintenance therapy. In addition, it is not uncommon for pediatric hematologists to observe children with RBC aplasia where there is no obvious diagnosis, although many are considered to be variants of Diamond-Blackfan anemia. Several important questions about RBC hypoplastic anemias in children need to be resolved; it is hoped that this will be accomplished in the next decade. Do RBC hypoplastic crises associated with hemolytic anemia occur with viral infections other than HPV? What is the cellular pathophysiology in DBA and TEC? Does the apparent heterogeneity of these disorders reflect limitations of laboratory techniques or are we looking at several different diseases? Is acute leukemia a real complication of Diamond-Blackfan anemia? Is TEC a completely benign entity or will we see other long-term problems in these children? Is the incidence of TEC actually increasing? Will TEC-like problems be seen in other aged children? As a case in point, we recently observed a 16-year-old girl who presented with pure RBC aplasia that required RBC transfusion support for 5 months; she also received prednisone therapy. After 7 months, however, this young lady had a spontaneous remission, and now 4 years later she is normal and free of any hematologic abnormalities. This was a most unusual event in our experience and, in view of the apparent increasing incidence of TEC in young children, we queried whether we were observing an adolescent equivalent of this disorder. During the next several years the answer to this and the other questions posed herein should be available.

Hemolytic anemia in children.

This article provides an overview of hemolytic anemia in children. Main focus areas include acquired immune-mediated hemolysis, hemolytic anemia due to hereditary RBC disorders, hereditary hemolytic disorders caused by enzyme abnormalities, and hereditary hemolytic anemia due to hemoglobin abnormalities.

Erythrocyte enzyme disorders in children.

Erythrocyte metabolic abnormalities should be considered as a possible cause of hemolysis when there is no evidence of an immune-mediated hemolytic anemia, no consumptive red blood cell disorder, no morophologic or laboratory data to suggest a problem of the red cell membrane, and no evidence of a quantitative or qualitative defect in hemoglobin synthesis. Glucose-6-phosphate dehydrogenase deficiency is clearly the most common enzyme deficiency causing clinical problems.

Hematologic disorders in children from southeast Asia.

The overall laboratory features of the common RBC disorders occurring in Southeast Asians is summarized in Table 4. These erythrocyte disorders will continue to be important public health issues, and it has been predicted that most new cases of thalassemia in the United States will occur in this population group. The fertility rate in Southeast Asian families is very high, with an average of more than five children delivered by each married woman. This number of children is consistent with perceptions of ideal family size, and, to date, no evidence suggests any change in the size of Southeast Asian families who now reside in the United States. Moreover, attitudes about health care, reasons why one seeks medical attention, and a variety of other cultural issues may impair the effectiveness of genetic counseling and other preventive measures designed to reduce the incidence of serious blood diseases. Genetic screening and prenatal diagnosis clearly have led to a markedly decreased incidence of homozygous thalassemia disorders in high-risk Mediterranean populations throughout the world. With further assimilation into Western culture, a similar disease may occur in the Southeast Asian population also.

Transient erythroblastopenia of adolescence.

This case report describes a 16-year-old girl with pure red cell aplasia of 7 months duration. The erythrocyte characteristics and in vitro culture of erythroid progenitors was similar to that found in transient erythroblastopenia of childhood (TEC), a disorder most commonly seen in children 2 to 6 years of age. This case may represent the adolescent equivalent of TEC.