NEOPLASIA AND DOWNS SYNDROME

Esthesioneuroblastoma in a boy with 47, XYY karyotype

Neuroblastomas are sometimes associated with abnormal constitutional karyotypes, but the XYY karyotype has been rarely described in neuroblastomas. Here, we report a case of an esthesioneuroblastoma in a boy with a 47, XYY karyotype. A 6-year-old boy was admitted to our hospital because of nasal obstruction and palpable cervical lymph node, which he first noticed several days previously. A polypoid mass in the right nasal cavity was detected through sinuscopy. Biopsy of the right nasal polyp was performed. Based on the result, the patient was diagnosed with a high-grade esthesioneuroblastoma. Nuclear imaging revealed increased uptake in both the right posterior nasal cavity and the right cervical IB-II space, suggesting metastatic lymph nodes. Cytogenetic analysis revealed a 47, XYY karyotype. Twelve courses of concurrent chemotherapy were administered. Three years after the completion of chemotherapy, the patient had had no disease recurrence. He manifested behavioral violence and temper tantrums, so we started methylphenidate for correction of the behavior.

Both normal memory counts and decreased naive cells favor intrinsic defect over early senescence of Down syndrome T lymphocytes

Because of their increased malignancies, autoimmune diseases, and infections, patients with Down syndrome (DS) show features of immunodeficiency. The DS thymus and T lymphocyte subsets have indeed proven to be different, and this has been interpreted as precocious aging. Our study on T lymphocyte subpopulations in DS shows that the normal expansion of naive helper (CD4CD45RA) and cytotoxic (CD8CD45RACD27) T lymphocytes is lacking in the first years of life; this is more logically explainable with an intrinsic T lymphocyte defect. Furthermore, memory cell numbers are not different from age-matched controls (AMC), which does not support the hypothesis of precocious aging. Although the absolute numbers of T lymphocyte subpopulations approach AMC levels toward adulthood, the persistent clinical problems suggest that these cells may not function optimally. However, the clinical picture does not fit severe T lymphocyte deficiency. The latter concept is also supported by our finding that cytomegalovirus (CMV)-seropositive DS children show similar numbers of terminally differentiated cytotoxic T lymphocytes when compared with healthy children, not increased numbers as are seen in immunocompromised hosts.

Intrinsic defect of the immune system in children with Down syndrome: a review

Down syndrome (DS) is the most frequent cause of mental retardation in man. Immunological changes in DS have been observed since the 1970s. The neurological system appears to be ageing precociously, with early occurrence of Alzheimer disease; until now, the observed immunological differences have been interpreted in the same context. Looking back at past and present results of immunological studies in DS children in relation to the clinical consequences they suffer, we conclude that it is more likely that the DS immune system is intrinsically deficient from the very beginning.

Aspects of digestive tract tumors in Down syndrome: a literature review

The purpose of this study was to describe the digestive neoplasms found in persons with Down syndrome. Due to intellectual disability, persons with Down syndrome do not convey their symptoms and pain, leading to delayed diagnosis and potentially worse outcome. It is thus important to know which organs are at risk for tumors and possible tumor risk factors. In a review of the literature, we found 13 benign tumors and 127 cancers in 1 fetus, 8 children, and 131 adults with Down syndrome. The review suggests a decreased incidence of digestive cancer, however, with a possible increased incidence of neoplasms of the pancreas and gallbladder. The distribution of cancers is distinct from that in the general population and that in persons with other intellectual disabilities who share the same life conditions, suggesting that constitutional protective factors exist. This review may allow a more specific, adapted medical follow-up for persons with Down syndrome and could help to elucidate the oncogenesis of digestive neoplasms.

Organ transplantation, organ donation and mental retardation

We reviewed the literature on accessibility and outcomes of organ transplantation in individuals with mental retardation (MR) and on the prevalence of organ donation in this population. Six centers have published outcome data on renal transplantation in 34 individuals with MR. The one- and three-yr patient survival rates were 100% and 90%, respectively. The studies reported good compliance with post-transplant medications due to consistent support from family members or caregivers. The outcome studies for liver and heart transplantation among these individuals are limited. The literature on organ donation in individuals with MR is mostly concerned with legal issues. The courts generally permit organ donations when such is in the best interests of the donor.

Down syndrome with low hypodiploidy in precursor B-cell acute lymphoblastic leukemia

We describe the rare finding of a 33-month-old child neonatally diagnosed with Down syndrome, who presented with pre-B acute lymphoblastic leukemia (ALL) with a pretreatment bone marrow karyotype in which a low hypodiploid cell line (38 chromosomes) was identified in 17/19 cells studied. The abnormal cell line retained the extra constitutional chromosome 21. Hypodiploidy (loss of one or more chromosomes) is seen in approximately 5% of all childhood pre-B ALL cases and in approximately 2.2% cases of individuals with a constitutional trisomy 21. Low hypodiploidy, associated with a high risk of relapse, is rare in pediatric ALL cases in the general population, and, to our knowledge, is previously unreported in patients with trisomy 21.

Clinical and biological characteristics of acute lymphocytic leukemia in children with Down syndrome

Twenty-eight children with Down syndrome (DS) and acute lymphocytic leukemia (ALL) were compared to non-DS control leukemics matched by age, white blood cell (WBC) count, and treatment protocol to evaluate presenting manifestations, toxicity, and outcome. The DS children with ALL did not have unique clinical or biologic characteristics to distinguish their disease from that of non-DS patients. Eleven of the DS patients had successfully banded cytogenetic studies of their leukemic cells with the distribution of model chromosome number of 46 (n = 1), 47 (2), 48 (5), and greater than 50 (3). The abnormal leukemic line involved an isochromosome of the long arm of chromosome 9[i(9q)] in 3 cases. Multiagent chemotherapies induced complete remissions in 25 patients (85%), yet overall 5 year event-free survival was only 23 +/- 8% when compared to 64 +/- 9% for control children receiving similar therapies (P less than 0.01). A significant cause of treatment failure was late marrow recurrence in the DS children. Host toxicity was striking in these children. Severe congenital heart disease present in one-third contributed to 2 deaths during antileukemia therapy. Hyperglycemia secondary to diabetogenic agents and repeated bronchitis were common toxicities. Intolerance to the antifolate methotrexate with severe gastrointestinal and skin toxicities was universal. We conclude that the poor prognosis for the child with DS and ALL stems in part from their increased risk of complications and toxicity from intensive modern leukemia therapies, specifically antifolates.

Immunology of Down syndrome: a review

Subjects with Down syndrome (DS) have a high mortality due to infections and a high risk of developing malignancies. These observations, together with the demonstration of a frequent occurrence of HBsAg carrier state and of autoantibodies, have prompted investigations of the immune function in DS. Thymic morphological and functional abnormalities have been demonstrated. Peripheral blood mononuclear cells of DS subjects have been shown to include a high number of T lymphocytes with low avidity for sheep erythrocytes and a very high percentage of cells with an NK phenotype. However, NK activity is low in DS. Production of some important cytokines, such as IL-2, is depressed, thus contributing to T-cell derangement. Abnormalities of the B-cell compartment were also demonstrated, with a tendency towards high IgG and low IgM serum levels. Controversial results have been obtained with regard to antigen-specific antibody response. Also phagocytes of DS subjects display some characteristic functional impairments, with low chemotactic ability and reduced production of oxygen radicals. Despite the clearly established and rather detailed evidence of immune derangements, therapeutic trials have been anecdotal and resulted in marginal effects. HBV vaccination is highly advisable in DS because of the high risk of becoming chronic HBV carriers once infected.

Intrathymic deficient expansion of T cell precursors in Down syndrome

To correlate the intrinsic cellular immunodeficiency, which is a major cause of increased susceptibility to polytopic infections in Down syndrome (DS) patients, with the histologic abnormalities observed in the thymus of these patients, we have studied thymus fragments and thymocyte cell suspensions from 15 non-institutionalized DS subjects. Comparing to the control age-matched samples, a reduced thymic cortex and a distinct depletion of CD1-positive (+) cells was observed by immuno-histologic examination. The phenotypic analysis of unselected thymocytes showed a significant reduction of CD3+, CD1+, CD4+, and CD8+ cells. When the total thymocyte population was separated into 10 fractions, using a continuous Percoll density gradient, a difference in cell distribution was observed. DS thymuses are almost devoid of high-density thymocytes (fractions 6-9) while more than 75% of the cells were recovered in the lightest 3 fractions (Frs). In addition, these thymuses were characterized by a marked depletion of CD1+ cells and by a conspicuous reduction of CD3+ cells normally present in the high-density Frs. On the other hand, the lightest 3 Frs of DS subjects were enriched in low-density CD1+ cells. Although enriched in these cells, normally characterized by a high mitotic activity, Fr1 DS thymocytes showed a reduced spontaneous proliferative capacity. When the expression of T cell receptor alpha- and beta-subunits was studied, the percentages of cells stained with anti-alpha and anti-beta antisera were found to be reduced in DS unfractionated thymocytes. The reduced number of high-density CD1+ thymocytes associated with a reduced spontaneous proliferative activity of low-density CD1+ thymocytes suggests that in DS thymuses there is a deficient expansion of immature T cells, resulting in a reduction of the various thymocyte subpopulations, including the thymocyte pool which differentiates into functionally mature T cells expressing the alpha-beta T cell receptor.

Distribution of X-ray-induced chromosome breakpoints in Down syndrome lymphocytes

Down syndrome (DS) individuals are known to be predisposed to develop leukemia and their lymphocytes are highly sensitive to the induction of chromosome aberrations by X-rays. A study was conducted to identify the chromosome breakpoints and to evaluate whether site specificity for chromosome breakage and rearrangement may exist which may explain the predisposition phenomenon. DS lymphocytes at the G1 phase of the cell cycle were irradiated with 300, 450, and 600 rad of X-rays. Cells were harvested after 3 days in culture and 193 G-banded karyotypes were analyzed to identify the induced chromosome abnormalities. Out of 273 breakpoints identified, 122 were involved in the formation of stable chromosome rearrangements and 151 in the formation of unstable abnormalities. The Poisson analysis of these breakpoints demonstrated that 16 chromosome bands located in chromosomes 1, 3, 7, 12, 17, 19 and X were preferentially involved in breakage and rearrangement (P less than 0.05). These 16 bands are also found to be locations of "cancer breakpoints," oncogenes, or fragile sites. Many abnormal cells were observed to carry stable chromosome rearrangements only. Therefore, these cells are presumed to be compatible with survival and to be "initiated" in the transformation process. We propose that similar stable and site-specific chromosome rearrangements may exist in proliferating cells in DS individuals after exposure to clastogens and that this abnormality predisposes them to develop leukemia.

Morphological and immunohistochemical study of Down syndrome thymus

The incidence and severity of various histologic changes were studied in the thymuses from 35 Down syndrome (DS) patients. Variable histologic alterations up to fibrotic involution of the gland were found. In addition, immunohistochemical investigation showed a reduction or absence of interdigitating reticulum cells roughly correlated with the severity of morphologic changes. The complex architectural and cellular thymic alterations, concerning both cortical and medullary microenvironment, could be correlated with the imbalances of immunity in DS patients.

Perinatal and reproductive factors: a report on haematological malignancies from the UKCCS

The United Kingdom Childhood Cancer Study was designed to examine the potential aetiological role of a range of perinatal and reproductive factors. Our use of clinical records permitted a more exact characterisation of reproductive events than is possible in investigations that rely on self-reporting; and the increased specificity with which antecedent events were measured produced more precise risk estimates, albeit ones based on progressively smaller numbers. Information on the conduct of this component of the study and results for 1485 children with haematological malignancies and 4864 controls are presented. The 'find' rate for obstetric records was high at 86% for cases, with 81% having information on both matched controls. Associations were seen for severe hyperemesis (Odds Ratio=3.6, 95%Confidence Interval=1.3-10.1, for all leukaemias), polyhydramnios (OR=4.0, 95%CI=1.5-10.3, for acute myeloid leukaemia (AML)), anaemia (haemoglobin <10 g, OR=2.6, 95%CI=1.7-4.1, for AML), and pre-eclampsia (OR=1.7, 95%CI=1.1-2.7, for non-Hodgkin's lymphoma). Babies who developed leukaemia were heavier at birth (>4000 g, OR=1.2, 95%CI=1.0-1.4), as were their older siblings (>4000 g, OR=1.4, 95%1.0-1.9). Mothers' whose children developed common B-cell precursor acute lymphoblastic leukaemia (ALL) were more likely to have had a previous molar pregnancy (OR=5.2, 95%CI=1.9-14.7). Gender-specific analysis revealed that findings often differed markedly for boys and girls; and, in common with other reports, strong associations with Down's syndrome were seen for both ALL and AML.

Lymphoblast biology and outcome among children with Down syndrome and ALL treated on CCG-1952

BACKGROUND

Patients with Down syndrome (DS) and standard risk (SR) acute lymphoblastic leukemia (ALL-DS) are reported to have inferior event free (EFS) and overall survival (OS) compared to patients without DS (ALL-NDS).

PROCEDURE

We compared the prevalence of favorable and unfavorable clinical and biologic features, toxicity and outcome within the ALL-DS and ALL-NDS cohorts of 2,174 eligible patients with SR-ALL enrolled on CCG-1952.

RESULTS

Fifty-nine patients (3%) had ALL-DS. DS patients were less likely to have either favorable (hyperdiploidy, triple trisomy of chromosomes 4, 10, and 17, TEL-AML1 rearrangement) or unfavorable (T-cell ALL, hypodiploidy, adverse translocations) biologic features. Toxicity occurred significantly more often and number of days hospitalized was significantly greater in ALL-DS than in ALL-NDS. ALL-DS patients had an inferior 4-year EFS compared to the NDS cohort. However, EFS was equivalent when the comparison excluded ALL-NDS with favorable biologic features. OS was significantly inferior for ALL-DS.

CONCLUSIONS

The absence of favorable biologic features within ALL-DS contributes to the difference in EFS previously observed between DS and NDS SR-ALL cohorts.

Fetal liver hyperechogenicity on sonography may be a serendipitous sign of a transient myeloproliferating disorder

OBJECTIVE

To demonstrate that thorough antenatal and postnatal investigations are helpful in any genetic syndrome.

CASE REPORT

A woman without a specific risk had a finding of hyperechogenic foci at ultrasound. Karyotype on fetal blood was 47, XY+21 and extensive biochemical investigation revealed abnormal liver function. Given the suspicion of a coincidental hepatic compromise, targeted postmortem examination was performed, which showed hepatic fibrosis, megakaryocytes proliferation and invasion of sinusoid capillaries, all suggestive of a transient myeloproliferative disorder.

CONCLUSION

When compared with chorionic villous and amniotic fluid sampling, fetal blood allows the collection of additional data, which may help in understanding the pathological process behind an apparently serendipitous association.

Gastrointestinal stromal tumor in an XYY/XY male

A 32-year-old patient was diagnosed with a gastrointestinal stromal tumor of the small bowel. The pathologic diagnosis was confirmed by positive immunochemistry against CD34, and against CD117, the tyrosine-kinase c-kit. We performed a karyotypic analysis on the basis of the patient's tall stature and speech difficulties. One hundred thirty-two metaphases were obtained on PHA-stimulated peripheral blood; 123 of them presented an extra chromosome Y. Fluorescence in situ hybridization using a Y satellite III probe showed the presence of a sole copy of chromosome Y in the tumor cells precluding a direct relationship between the extra chromosome Y and the initiation of the tumor. This is, to our knowledge, the second occurrence of a nonhematologic malignancy reported in this genetic disorder. A review of the malignancies observed in men with the XYY constitution is presented.

Plasma pharmacokinetics of etoposide (VP-16) after i.v. administration to children

The pharmacokinetics of etoposide (VP-16), a semi-synthetic derivative of podophyllotoxin, were studied in 16 pediatric patients (median age 8.3 years; range 4 months to 22 years) including two girls with Down's syndrome (DS). The drug was administered as infusions (1-3 h) in a wide range of doses (9-322 mg, corresponding to 32-210 mg/m2). The area under the plasma concentration versus time curve (AUC), dose normalized by the body surface area, was independent of age, while AUC normalized by the dose in mg/kg increased with increasing age of the patients. The interpatient variability of AUC, normalized for the dose in mg/m2, was 23% (CV) compared to 32% (CV) normalized for the dose in mg/kg. The terminal half-life time was 4.1 h (median value; range 2.0-7.8 h). The pharmacokinetics of etoposide in children with DS and chromosomally normal children were very similar with regard to systemic drug exposure and plasma half-life time. From the pharmacokinetic point of view it was therefore not necessary to make any dose modifications in the two girls with DS. The two DS patients did not experience any enhanced degree of toxicity from their etoposide treatments. The results support that dosing of etoposide to children should be based on body surface area.

Partial impairment of immune functions in peripheral blood leukocytes from aged men with Down's syndrome

Down's syndrome (DS) has been considered a model of accelerated aging and of Alzheimer's disease. We investigated immunologic functions using peripheral blood leukocytes in order to correlate the production of cytokines and development of neuropathological changes of Alzheimer type in aged persons with DS. Cytokine production (IL-1beta, IL-2, IL-6, IL-8, and TNF-alpha), phytohemagglutinin (PHA)-stimulated proliferation of nonadherent monocytes, and superoxide anion production from polymorphonuclear leukocytes were measured. PHA-stimulated proliferation in aged individuals (>30 years old) with DS was significantly lower than that of age- and sex-matched controls (DS vs control, 55,707+/-5810 vs 88,310+/-6994 cpm, P < 0.001). PHA-stimulated IL-2 production was also significantly decreased in aged individuals with DS (DS vs control, 7.1+/-2.1 vs 10.7+/-1.3 ng/ml). Interestingly, the decrease of proliferation and IL-2 production in aged males with DS is significantly greater than in aged women with DS. PHA-stimulated proliferation and IL-2 production of nonadherent monocytes in females was not significantly reduced. IL-1beta production by LPS-activated adherent monocytes was significantly decreased in older adults with DS compared with non-DS controls. Other immune parameters measured in DS were not significantly different from that of age-matched controls. We conclude that there is partial impairment of T lymphocytes in aged persons with DS that is significantly greater in males than in females.

47,XYY karyotype in acute myeloid leukemia

A case of acute myelomonocytic leukemia (AMMoL; M4) with a 47,XYY karyotype is reported. This chromosome aneuploidy was found in both bone marrow cells and mitogen-stimulated lymphocytes. The contribution of XYY chromosomal constitution in the pathogenesis of AMMoL is controversial.

T cell activation deficiency associated with an aberrant pattern of protein tyrosine phosphorylation after CD3 perturbation in Down's syndrome

Children affected by Down's syndrome (DS) have an increased susceptibility to viral or bacterial infections and leukemia, associated with several abnormalities of the immune system. We investigated whether the T cell defect was qualitative in nature and associated with abnormalities of the early events occurring during cell activation. The proliferative response of lymphocytes from DS individuals after CD3 cross-linking was clearly depressed, as already reported. In contrast, phorbol ester and ionomycin were able to induce cell cycle progression in DS, suggesting a defect in the early stages of the signal transduction through a T cell receptor/CD3 (TCR/CD3) complex upstream of protein kinase C activation. The functional impairment in DS was not related either to a decrease of circulating mature-type CD3+ cells, which express high levels of surface of CD3 molecules, or to a decrease of the CD4+ subpopulation. The analysis of phosphotyrosine-containing proteins after the cross-linking of CD3 molecules in DS lymphocytes revealed a partial signaling, characterized by increased phosphorylation of proteins of 42-44 kD, comparable to that observed in control subjects, but not of proteins of 70 and 21 kD. Moreover, although the "anti-anergic" gamma element of IL-2, IL-4, IL-7, and IL-15 receptors was normally tyrosine-phosphorylated during cell activation, the CD3 zeta-associated protein kinase (ZAP-70) was not. Our results indicate that in DS there is a T cell activation defect, characterized by partial signal transduction through a TCR/CD3 complex, and associated with a selective failure of ZAP-70 tyrosine phosphorylation.

Malignancies in Down syndrome

Down Syndrome (DS) is associated with an increased incidence of malignancies, especially leukaemias. We came across 8 DS children presenting with malignancies and having trisomy 21 as the sole cytogenetic abnormality. Of these 8 DS cases, 4 presented with acute lymphocytic leukaemia, 2 with acute myeloid leukaemia and one case each with Hodgkin's disease and Wilms' tumour. There are contradictory reports regarding the distribution of myeloid versus lymphoid malignancies in DS children and their response to therapy. The exact mechanism by which patients with DS are predisposed to develop malignancies is unclear. However, presence of the extra chromosome no. 21 is presumed to disrupt the genetic balance which increases generalized susceptibility to genetic and environmental trauma. Furthermore, an increased methotrexate toxicity observed in these patients should also be taken into consideration in designing treatment for DS children with malignancies.

Klinefelter syndrome and non-Hodgkin lymphoma

Patients with a 47,XXY karyotype (Klinefelter syndrome) appear to have an increased risk of developing cancer, especially male breast cancer and germ cell tumors, but rarely malignant hematologic disorders. We report a patient with a low grade B-cell non-Hodgkin lymphoma with a 47,XXY karyotype in both the tumor and constitutional cells. This is only the 13th reported case of malignant lymphoma in a patient with Klinefelter syndrome. Although some authors postulate that the 47,XXY karyotype may be a predisposing factor in the development of hematological malignancies, the lack of reported cases suggests that such associations may be no more than chance findings.

Intracranial germinoma with Down's syndrome: a case report and review of the literature

BACKGROUND

Down's syndrome's association with malignancies such as leukemia is well known, but its association with brain tumor appears to be rare. We reviewed such rare cases of Down's syndrome and intracranial germ-cell tumor.

CASE REPORT

A 10-year-old boy with Down's syndrome and intracranial germinoma located in the left basal ganglia is reported. The patient presented with right hemiparesis and was treated with a combination of surgery, chemotherapy with cisplatin and etoposide, and irradiation.

CONCLUSIONS

We speculate that the percentage of germ-cell tumors is high among Down syndrome patients with brain tumors and that the most common site is the basal ganglia.

Hodgkin's disease in association with Down syndrome: a case report

The increased incidence of malignancies, especially acute leukemia, in Down syndrome has been clearly established. The association of Hodgkin's disease with Down syndrome has not been extensively documented, and only a few cases have been reported. We present here a case report of Hodgkin's disease in an 11-year-old female child with Down syndrome. The child presented with a stage IVB nodular sclerotic Hodgkin's disease and died of progressive disease. We also present a brief review of the mechanisms of development of malignancy in Down syndrome.

Aspects of the neoplasms observed in patients with constitutional autosomal trisomy

A review of the literature reveals numerous clinical case reports, systematic histologic analyses, epidemiologic studies, and large series of tumors showing that subjects with trisomy 8, 9, 13, 18, and 21 have an excess of hematologic and various solid tumors compared to the general population. These tumors more frequently affect particular organs for a given type of trisomy. A large proportion of tumors are observed during fetal and neonatal life, are incompletely developed, and subsequently regress. In older children or even adults, tumors are less frequent, are often found on the same organs as earlier in life, are more aggressive, and do not involute. The mechanism responsible for the development of these neoplasms could be similar to that which generates the malformations in these children and may result from cooperation of the chromosomal abnormality with physiologic growth phenomena, which are particularly active early in life. Trisomic subjects must be carefully followed in order to detect tumors as early as possible and to allow treatment under optimal conditions.

Behavioral assessment of the Ts65Dn mouse, a model for Down syndrome: altered behavior in the elevated plus maze and open field

The Ts65Dn mouse carries a partial trisomy for mouse chromosome 16 in a region that has high homology to the Down syndrome (DS) region of human chromosome 21 and is, thus, a potential animal model of DS. The focus of the present study was to begin to characterize the behavioral phenotype of this mouse to assess its usefulness as a model of aspects of the DS phenotype. The behavior of Ts65Dn and littermate control mice was assessed in the elevated plus maze, lighted and dark open field, and a step-down passive avoidance task. The behavior of Ts65Dn mice in these tests differed considerably from the nontrisomic controls. In the elevated plus maze, Ts65Dn had more total arm visits than controls, showed a higher percentage of arm visits to the open arms than control mice, and showed no preference for the closed arms. Ts65Dn mice were more active in both open-field situations, regardless of light condition, and ventured into the center of the arena more than controls. Lighting in the open field had moderate effects on the activity of the Ts65Dn mice, but control mice were, as expected, much more active in the dark than the light. The trisomic mice learned and retained the step-down passive avoidance task in the same number of trials as the controls. Overall, these data indicate that Ts65Dn mice are more active than control mice in two testing situations. Most striking is the finding that the Ts65Dn mice were much less responsive to variations in environmental cues to which normal mice are quite sensitive. These data not only begin to characterize systematically the Ts65Dn phenotype, but also raise several interesting issues about the sources of the aberrant behaviors observed in these mice.

Duplication and loss of chromosome 21 in two children with Down syndrome and acute leukemia

Acute leukemia in Down syndrome (DS) is often associated with additional changes in the number or structure of chromosome 21. We present two DS patients whose leukemic karyotypes were associated with changes in chromosome 21 ploidy. Patient 1 developed acute lymphocytic leukemia (type L1); disomy for chromosome 21 was evident in all blast cells examined. Loss of the paternal chromosome in the leukemic clone produced maternal uniparental disomy with isodisomy over a 25-cM interval. The second patient had acute monoblastic leukemia (type M5) with tetrasomy 21 in all leukemic cells. DNA polymorphism analysis showed duplicate paternal chromosomes in the constitutional genotype. The maternal chromosome was subsequently duplicated in the leukemic clone. The distinct inheritance patterns of chromosome 21 in the blast cells of these patients would appear to indicate that leukemogenesis occurred by different genetic mechanisms in each individual.

Immunological features of Down's syndrome: a review

Young patients with Down's syndrome (DS) have high rates of infections, malignancies and autoimmune phenomena. Therefore, DS may be considered as a model of precocious, abnormal ageing of the thymus-dependent system in man. In DS children less than 6 years of age, the levels of serum immunoglobulins did not differ from healthy controls, but after that age, considerable hyper-IgG and -IgA were found. Furthermore, high levels of IgG1 and IgG3 have been found, whereas a progressive decline of IgG2 and IgG4 with age has been observed. The frequency of hepatitis B virus carriers even in the youngest age group is much higher among DS children. It has been reported that an IgG response was detectable in 75% of controls after HBsAg vaccination as compared to the 16.6% of DS patients. The presence of autoantibodies against human thyroglobulin did show a positive association with HB Virus Ag carriers, but only in the oldest DS subjects. Natural antibodies against intestinal antigens are low, while in the presence of cow's milk, abnormally high titres against casein and beta-lactoglobulin were present. High levels of IgG antibodies against gliadin have been observed. In spite of a normal percentage of CD3- and CD2-positive lymphocytes, a high proportion of cells express low-avidity receptors for sheep erythrocytes. Although the proportion of CD4+ T-lymphocyte helper-cells is normal, a marked imbalance in the CD4+ subpopulations has been documented. The percentage of suppressor-cytotoxic CD8+ lymphocytes is markedly increased. The responses to phytohemagglutinin and concanavalin A are within the normal range in the first decade of life and decline progressively thereafter. A recent study reported defective proliferative response to allo-mixed lymphocyte culture, with decreased expression of the membrane CD25, low secretion of interleukin 2 in the supernatant and depressed allo-specific cytotoxic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

X-ray-induced chromatid damage in cells from Down syndrome and Alzheimer disease patients in relation to DNA repair and cancer proneness

Frequencies of chromatid aberrations in response to G2-phase x-irradiation were compared in PHA-stimulated blood lymphocytes from healthy control subjects, Down syndrome (DS) patients, and Alzheimer disease (AD) patients. In cells arrested with Colcemid immediately (0-30 min) after x-irradiation, DS, AD, and control cells showed similar high frequencies of chromatid breaks and gaps, representing unrepaired DNA strand breaks. Frequencies had decreased in AD and control cells arrested 30-90 min after irradiation. However, DS cells had two- to three-fold higher frequencies than AD or control cells. This result indicates deficient repair of the DNA damage in DS cells. Similar responses were obtained with lymphocytes from four of seven DS parents tested and with skin fibroblasts from DS patients compared to age-matched controls. Addition of 1-beta-D-arabinofuranosylcytosine (ara-C), an inhibitor of the repair polymerase, after x-irradiation during G2 phase increased the frequencies of chromatid breaks and gaps in lymphocytes from control and AD donors significantly more than in those from DS patients. This result indicates a deficiency in DS cells in incision at sites of x-ray-induced damage. Thus DS, like other cancer-prone genetic disorders, has a G2-phase DNA repair deficiency in strand break repair and also a second DNA repair deficiency in incision activity.

Acute myelomonocytic leukemia in a XYY man

A case of acute myeloid leukemia (M4) in a 29-year-old male with a 47,XYY karyotype is reported. This aneuploidy was found in both bone marrow cells and mitogen-stimulated lymphocytes. Monosomy 7 correlated with myelodysplastic features. The possible role of XYY in increasing the risk of leukemia is discussed.

Effect of increased gene dosage expression on the alpha-interferon receptors in Down's syndrome

The gene coding for the alpha, beta-interferon (alpha, beta-IFN) receptor is localized to chromosome 21. Cells from patients with Down's syndrome contain an extra chromosome 21, and thereby an expected 1.5-times increase in the number of genes located to this chromosome and in consequence a 1.5-times increase in cell surface alpha-IFN receptors. Actual measurements of these by competition binding experiments with human recombinant alpha-IFN on peripheral blood mononuclear cells (PBMC) from patients with Down's syndrome resulted in a mean of 1.69, which is in accordance to the theoretical 1.50, but slightly overestimated due to the calculation method. The increased gene dosage of the alpha-IFN receptor was quantitatively verified by Southern blot-hybridizations. Further characterization of alpha-IFN receptor binding showed insignificant differences in dissociation constants among patients and healthy individuals.

Transient abnormal myelopoiesis in Down's syndrome

Recent data have elucidated the pathogenesis of transient abnormal myelopoiesis (TAM) to a great extent. TAM is a monoclonal disorder which resolves spontaneously and the target cell in this disorder is a multipotent stem cell which is capable of differentiating into megakaryocytes. The pathogeneses of TAM/AMKL (acute megakaryoblastic leukemia) appears to be closely associated with abnormal quality and quantity of a gene located on chromosome 21. AMKL developing after the regression of TAM appears to come from the same clone as the TAM, which apparently experiences some kind of genetic alterations. It seems that the gene responsible for TAM will soon be cloned in the near future. However, the mechanism of spontaneous regression of TAM has as yet not been clarified. The expanding clone in the transient physiological immunodeficient state, during the perinatal period, might be eliminated with the maturation of more mature immunosurveillance. Alternatively, the TAM clone might be destined to undergo spontaneous death, which is called "programmed cell death" (apoptosis). The mechanism of this phenomenon awaits further elucidation.