Assessment of Myocardial Function in Children before and after Autologous Peripheral Blood Stem Cell Transplantation

BACKGROUND

Increased interest is focused on the long-term adverse effects of bone marrow transplantation. Subclinical cardiac involvement appears common in adults, but only a few reports have examined pediatric patients.

MATERIALS AND METHODS

A prospective case-control study of 19 children with normal cardiac function undergoing autologous hematopoietic stem cell transplantation (HSCT) was performed. Tissue Doppler imaging (TDI) and echocardiographic measurements were obtained according to the guidelines of the American Society of Echocardiography before and 3 months after HSCT.

RESULTS

Lateral mitral annulus before HSCT showed significant reduced mitral systolic annular velocity (P < 0.0001), early diastolic annular velocity (P < 0.0001), late diastolic annular velocity (P = 0.02) and prolonged isovolumetric relaxation time (IRT) (P < 0.0001) compared with control. Significant reduced mitral systolic annular velocity (P < 0.0001), early diastolic annular velocity (P = 0.0005) and Em/Am ratio (P = 0.004), with higher late diastolic annular velocity (P = 0.02) and prolonged isovolumetric contraction time (ICT) (P = 0.003) and IRT (P = 0.002) after HSCT, were observed. Investigation of lateral tricuspid annulus showed nearly similar results as the lateral mitral annulus. LV and RV Tei indices were higher before HSCT compared with control and remained high after HSCT.

CONCLUSION

TDI detected subtle abnormalities in systolic and diastolic functions before and after HSCT, which suggests that a conditioning regimen may affect cardiac function.

Clinico-epidemiology of neuroblastoma in north east Egypt: A 5-year multicenter study

Neuroblastoma, an embryonal malignancy of the sympathetic nervous system, is the most frequent extracranial solid tumor The clinico-epidemiological features of neuroblastoma in infants and children were investigated between January 2005 and January 2010 at the Pediatric Oncology units of Mansoura, Zagazig, and Tanta University Children's Hospitals (Egypt). Of 142 cases of neuroblastoma, 10 were omitted from the study due to defective data. The median age of the patients was 30 months, with 75.8% aged ≥1 year and 24.2% aged <1 year at time of diagnosis. The male-to-female ratio was 1.06. Suprarenal glands were the most common primary tumor site (72.7%). The majority of the patients (76.7%) had stage IV disease. Favorable pathology was observed in 43.8% of patients, while 56.2% exhibited unfavorable pathology. The estimated survival rate of patients was 30.7±10.0%, and mean survival time was 24.2±5.2 months. The rate of mortality was 28.6% for patients aged <1 year, and 81.8% for those aged ≥1 year (P=0.005). For patients with favorable pathology, the rate of mortality was significantly lower (28.6%) compared with that of patients with unfavorable pathology (77.8%; P=0.049). Although the association between outcome and each of the primary tumor sites, children's oncology group risk and gender was statistically insignificant, a large effect size was identified between outcome and primary tumor site, as well as children's oncology group risk and a medium effect size was identified between outcome and gender. Additionally, an age of ≥1 year was associated with unfavorable pathology (P=0.024), stage IV disease (P=0.026) and a suprarenal primary tumor site (P=0.001).

Renal complications of beta-thalassemia major in children

The success that has been made in the care of patients with thalassemia has led to the emergence of unrecognized complications including several renal abnormalities. Chronic anemia and iron overload as well as the use of iron chelator are believed to lie behind these abnormalities. Many investigators document the presence of tubular dysfunction and abnormalities in glomerular filtration rate in these patients. In this review we will discuss the updates in the diagnosis, pathogenesis and prevention of renal complications of thalassemia.

Deviating from safety guidelines during deferiprone therapy in clinical practice may not be associated with higher risk of agranulocytosis

BACKGROUND

A risk associated with the iron chelator deferiprone is the development of neutropenia or agranulocytosis. Accordingly, the product label recommends weekly blood monitoring and immediate interruption of treatment upon detection of an absolute neutrophil count (ANC) <1.5 × 10(9)/L, out of concern that continued therapy might lead to a more severe drop. However, it is uncertain how these recommendations are followed under real-life conditions and, if they are not followed, whether continuation of therapy results in increased incidence of agranulocytosis.

PROCEDURE

This non-interventional surveillance program assessed the monitoring of deferiprone therapy in clinical practice. A total of 294 patients with transfusion-dependent anemias received deferiprone, as monotherapy or with another chelator, for up to 1 year. The participating physicians were not given any instructions about treatment and monitoring beyond being referred to the information in the package insert.

RESULTS

ANC monitoring was conducted at an average interval of 5 ± 4 weeks, and deferiprone was not always interrupted upon detection of neutropenia. One patient (0.3%) experienced agranulocytosis, and nine others (3%) experienced a total of 11 episodes of neutropenia. All neutropenia episodes resolved; median time to resolution was similar whether or not treatment was interrupted; and no case of neutropenia progressed to agranulocytosis.

CONCLUSIONS

These data indicate that less frequent ANC monitoring and continuation of deferiprone therapy during neutropenia are not associated with prolonged neutropenia or with progression to agranulocytosis.

Prognostic cytogenetic markers in childhood acute lymphoblastic leukemia: Cases from Mansoura Egypt

The objective of the work was to evaluate children with acute lymphoblastic leukemia (ALL) showing resistance to immediate induction chemotherapy in relation to conventional and advanced cytogenetic analysis. The study was conducted on 63 ALL children (40 males and 23 females) with age range 4.5 months-16 years (mean = 7.76 years). They included 37 cases who attained a true remission and 26 complicated by failure of remission, early relapse or death. They were subjected to history, clinical examination and investigations including CBC, BM examination, karyotyping, FISH for translocations and flowcytometry for immunophenotyping and minimal residual disease diagnosis. Cases aged < 5 years; male sex with organomegaly had better remission although statistically insignificant. Initially low HB < 8 gm/dl, high WBCs and platelet counts >50.000/mm(3) also showed better but non-significant remission rates. Most of our cases were L(2) with better remission compared to other immunophenotypes. About 40 informative karyotypes were subdivided into 15 hypodiploid, 10 pseudodiploid, 8 normal diploid and 7 hyperdiploid cases; the best remission rates were noticed among the most frequent ploidy patterns. Chromosomes 9, 11 and 22 were the most frequently involved by structural aberrations followed by chromosomes 5, 12 and 17. Resistance was noted with aberrations not encountered among remission group; deletions involving chromosomes 2p, 3q, 10p and 12q; translocations involving chromosome 5; trisomies of chromosomes 16 and 21; monosomies of 5 and X and inversions of 5 and 11. Our conclusions were that cytogenetic and molecular characterizations of childhood ALL could add prognostic criteria for proper therapy allocation.

Prognostic cytogenetic markers in childhood acute lymphoblastic leukemia: Cases from Mansoura, Egypt

OBJECTIVE

To evaluate children with acute lymphoblastic leukemia (ALL) showing resistance to immediate induction chemotherapy in relation to conventional and advanced cytogenetic analysis.

SUBJECTS AND METHODS

This work was conducted on 63 ALL children (40 males and 23 females) with age range 4.5 months-16 years (mean = 7.76 years). They included 37 cases who attained true remission and 26 complicated by failure of remission, early relapse or death. They were subjected to history, clinical examination and investigations including CBC, BM examination, karyotyping, FISH for translocations and flow cytometry for immunophenotyping and minimal residual disease diagnosis.

RESULTS

Cases aged < 5 years; male sex with organomegaly had better remission although statistically insignificant. Initially low Hb < 8 gm/dl, high WBCs and platelet counts > 50,000/mm(3) also showed better but non-significant remission rates. Most of our cases were L(2) with better remission compared to other immunophenotypes. Forty informative karyotypes were subdivided into 15 hypodiploid, 10 pseudodiploid, 8 normal diploid and 7 hyperdiploid cases; the best remission rates were noticed among the most frequent ploidy patterns. Chromosomes 9, 11 and 22 were the most frequently involved by structural aberrations followed by chromosomes 5, 12 and 17. Resistance was noted with aberrations not encountered among remission group; deletions involving chromosomes 2p, 3q, 10p and 12q; translocations involving chromosome 5; trisomies of chromosomes 16 and 21; monosomies of 5 and X and inversions of 5 and 11.

CONCLUSIONS

Cytogenetic and molecular characterizations of childhood ALL may add prognostic criteria for optimal therapy allocation.

Markers of apoptosis and proliferation related gene products as predictors of treatment outcome in childhood acute lymphoblastic leukemia

The aim of the study is to characterize markers of apoptosis in children with acute lymphoblastic leukemia (ALL) in relation to treatment outcome of the disease. The study was performed on 34 children with ALL and 39 healthy children as a control group. Apoptosis was assessed by cell morphology; DNA fragmentation; ELISA and RT-PCR for CD95, CD95L, BcL-2 and nuclear factor-kappa B (NF-kappaB); and flow cytometry for CD95, CD40, CD49d and CD11a. Apoptosis was significantly lower in patients than controls. Apoptosis detected by CD95 ligand was significantly lower in cases with no remission after treatment than those who achieved remission. Anti-apoptotic factors: CD40, BcL-2, and NF-kappaB were all found to be higher in cases than controls and in cases with no remission than those achieved remission. CD49d was significantly lower in cases than controls, and significantly lower in cases with who did not achieve remission. CD11a levels were similar in the various groups. Delayed apoptosis of ALL cells is genetically controlled either directly or indirectly by a network of oncogenes and tumor suppressor genes. CD40 appeared to stimulate both T and B lineage and is considered the most potent influencer and predictor of resistance to therapy. Inhibitors for the activity of CD40, Bcl-2 and NF-kappaB as well as stimulants to CD95 could have a potential therapeutic benefit.

Treatment for hepatitis C virus-induced portal hypertension in leukemic children

Children with acute leukemia are at high risk of hepatitis C infection, either by immunosuppression secondary to chemotherapy or by multiple transfusions of blood products during the course of the disease. Hepatitis C virus (HCV) infection constitutes a major problem during management of acute leukemia due to resultant portal hypertension or bleeding esophageal varices. Chronic HCV infection is a major cause of liver cirrhosis and hepatocellular carcinoma in leukemic survivors. The effect of amlodipine treatment on children with acute lymphoblastic leukemia (ALL) having portal hypertension secondary to HCV infection during maintenance chemotherapy has been studied. Sixty male children (mean age 11.83 ± 1.1 years) with ALL in remission and have HCV infection were included. Diagnosis of HCV infection was confirmed by real-time PCR. Thirty patients received 5 mg amlodipine orally per day for 4 weeks and compared to another 30 patients received placebo therapy and 30 age- and sex-matched children as a control group. Amlodipine significantly reduced the elevated portal blood pressure to normal level in doses which did not interfere with mechanism of action of chemotherapy (p ≤ 0.001). Treatment with amlodipine can be used to control portal hypertension in leukemic children having HCV-induced portal hypertension. HCV in leukemics could be virtually eliminated by proper testing of the blood transfusion pool.

Impact of anti-oxidant status and apoptosis on the induction phase of chemotherapy in childhood acute lymphoblastic leukemia

This study aimed to evaluate oxidative stress and apoptosis in childhood acute lymphoblastic leukemia (ALL) at diagnosis and their impact on outcome at the end of the induction phase. Our study included 50 newly diagnosed children with ALL. Evaluation of oxidative stresses (malondialdehyde and total anti-oxidant capacity) was made at diagnosis and at the end of the induction phase. Apoptosis level was determined by fluorometric terminal deoxynucleotidyl transferase dUTP nick end labeling system for patients at diagnosis and after 1 week of treatment. Our study showed that there was increased oxidative stress at diagnosis and after treatment with chemotherapy. Apoptosis index was higher after 1 week of treatment with chemotherapy when compared to its level at diagnosis.

Intracranial hemorrhage in acute and chronic childhood immune thrombocytopenic purpura over a ten-year period: an Egyptian multicenter study

Intracranial hemorrhage (ICH) is a rare but major cause of death in immune thrombocytopenic purpura (ITP). The authors reviewed data of 1,840 patient with ITP, from 5 pediatric hematology centers in Egypt from 1997 to 2007, to study the incidence and risk factors of ICH. Ten cases of ICH were identified with a median age at presentation of 7.5 years; 4 patients had acute ITP, 2 persistent and 4 chronic. The platelet count was <10 x 10(9)/l in 7 cases, and only 1 patient had a history of head trauma. Seven children were on treatment prior to or at the time of occurrence of ICH and all were treated by pharmacotherapy. Two children died shortly afterwards due to late referral to a specialized center. Our results suggest that treatment does not prevent ICH and that it can occur at any time during the course of the disease. Delayed referral can be considered a risk factor for unfavorable outcome of ICH, highlighting the importance of teaching sessions for patients and their parents to minimize subsequent morbidity and mortality of ICH in children with ITP.

Prevalence and prognostic significance of murine double minute protein-2 overexpression and P53 gene mutations in childhood acute lymphoblastic leukemia

The murine double minute protein-2 (MDM-2) oncogene is a determinant of embryogenesis, tumorigenesis, and cell cycle progression. The effects of MDM-2 on these processes depend, in part, on its ability to inactivate the p53 tumor suppressor gene. Our goal was to determine whether MDM-2 protein overexpressions or p53 gene mutations are a frequent event in poor outcome pediatric acute lymphoblastic leukemia (ALL). This work was conducted on 46 children with ALL (31 males and 15 females) with age range 2-18 years, 18 children with matched age and sex were enrolled in the study as a control group. The MDM-2 expression by flowcytometry and p53 gene status by PCR were determined in peripheral blood or bone marrow of ALL children (at initial diagnosis) and also of control group. The ALL children were treated by the modified BFM 76179 protocol of therapy, 29 patients (63%) achieved complete remission, while 17 patients (37%) were subsequently failed to achieve complete remission or relapsed within 6 months of achieving complete remission (CR). MDM-2 was significantly overexpressed in 15 ALL patients (32.6%), compared to that of healthy controls, 4 of them (4/15), were out of 29 cases of CR (13.8%), and the other 11 cases were out of 17 relapsed cases (64.7%). In contrast to overexpression of MDM-2, the mutation of p53 was detected in 6 (13%) out of 46 ALL patients at the initial time of diagnosis, 3 of them (10.3%) were out of 29 cases of CR and the other 3 cases (17.6%) were out of 17 of relapsed group, which is significantly higher than CR group (P < 0.05). In relapsed group, 2 patients out of 3 cases with p53 mutation were MDM-2 negative, also, all 3 cases of mutant P53 among patients in CR were negative MDM2. A positive correlation was found between the MDM-2 overexpression and initial WBCs count, blast cell counts in peripheral blood and presence of CNS blasts (p < 0.05, p < 0.05 and p < 0.05 respectively). These results indicate that MDM-2 is overexpressed in a significant number of childhood ALL, it is more frequent in relapsed cases and its frequency is not related to p53 status. Thus measuring of MDM-2 as a bad prognostic marker even in cases with non mutant P53 is very important. Moreover, MDM-2 may be a potential molecular target for production of new cancer therapy.

Prognostic cytogenetic markers in childhood acute lymphoblastic leukemia

OBJECTIVE

To evaluate children with acute lymphoblastic leukemia (ALL) showing resistance to immediate induction chemotherapy in relation to conventional and advanced cytogenetic analysis.

METHODS

This work was conducted on 63 ALL children (40 males and 23 females) with age range 4.5 months-16 years (mean = 7.76 years). They included 37 cases attained true remission and 26 complicated by failure of remission, early relapse or death. They were subjected to history, clinical examination and investigations including CBC, BM examination, karyotyping, FISH for translocations and flowcytometry for immunophenotyping and minimal residual disease diagnosis.

RESULTS

Cases aged 50.000/mm3 also showed better but non-significant remission rates. Most of the present cases were L2 with better remission compared to other immunophenotypes. Forty informative karyotypes were subdivided into 15 hypodiploid, 10 pseudodiploid, 8 normal diploid and 7 hyperdiploid cases; the best remission rates were noticed among the most frequent ploidy patterns. Chromosomes 9, 11 and 22 were the most frequently involved by structural aberrations followed by chromosomes 5, 12 and 17. Resistance was noted with aberrations not encountered among remission group; deletions involving chromosomes 2p, 3q, 10p and 12q; translocations involving chromosome 5; trisomies of chromosomes 16 and 21; monosomies of 5 and X and inversions of 5 and 11.

CONCLUSION

Some cytogenetic and molecular characterizations of childhood ALL could add prognostic criteria for proper therapy allocation.

Assessment of bcl-2 expression as modulator of fas mediated apoptosis in acute leukemia

Apoptosis is the primary mechanism through which most chemotherapeutic agents induce tumor cell death. The balance in the expression of pro (Fas/CD95) and anti-apoptotic protein (Bcl-2) may control the response of leukemic cells to chemotherapy and subsequently affect the patient's prognosis. The aim of this study was to determine the levels of Bcl-2 and Fas expression on blast cells from patients with acute leukemia and to correlate the degree of expression to the clinical and laboratory prognostic factors and the patient's outcome. Forty newly diagnosed patients with acute leukemia (16 ALL, 24 AML) were included in the study. Ten normal subjects of matched age and sex were studied as a reference control group. The degree of Bcl-2 and Fas expression on acute leukemia blast cells were assessed before the start of therapy and on mononuclear cells after 1 year of follow up, using flow cytometry. The degree of Bcl-2 and Fas expression were significantly higher in AML (P<0.01,<0.05, respectively) and ALL (P<0.01, <0.05, respectively) as compared to controls. The expression of Fas and Bcl-2 was related to FAB type with the highest Bcl-2 and lowest Fas expression in M5 and T-ALL (P<0.01, for all). In ALL, patients responding to induction chemotherapy revealed lower Bcl-2 and higher Fas expression when compared to non-responders (P<0.05). In contrast, in AML the difference between responders and non-responders to induction chemotherapy regarding Bcl-2 and Fas expressions was not statistically significant (P>0.05). Bcl-2 and Fas expression were significantly elevated in the relapsed acute leukemia group (in both AML and ALL) when compared to those in remission (P<0.01, <0.05, respectively). Bcl-2 and Fas expression at diagnosis was not significantly different when those surviving were compared to the group who had died, either in the ALL or AML groups (P>0.05). Bcl-2 expression was significantly correlated to bone marrow blast cell counts (R=0.6, P<0.01), blast cell distribution ratio (R=0.4, P<0.05) and lymphadenopathy (R=0.33, P<0.05). Whereas Fas expression was significantly correlated to bone marrow blast cell counts (R=0.52, P<0.01). In conclusion, assessment of Bcl-2 and Fas expression at diagnosis in acute leukemia (1) could predict responsiveness to induction chemotherapy in ALL but not in AML group but (2) could not predict patients out come both in ALL and AML groups.

HLA class II polymorphism in Egyptian children with lymphomas

The major histocompatibility complex (MHC) is a set of closely-linked genes encoded on the short arm of chromosome 6. It is important for understanding human immunological diseases, transplantation and in host defense against infection. The membrane proteins are two types; class I MHC proteins and class II MHC proteins. Strong arguments supporting genetic linkage between susceptibility to lymphomas and human leukocyte antigens (HLA)-class II are reported and give a clue about susceptibility or protection from the disease.

AIM

To evaluate the possible changes of HLA class II (DR, DQ) alleles in children with lymphoma.

METHODS

Thirty cases were included in this limited study. Nineteen cases of non Hodgkin's lymphoma (NHL) and eleven patients with Hodgkin's lymphoma (HD). Their ages ranged from 1.5 to 15 years. The control group consisted of 121 unrelated healthy subjects for DRB1 alleles and 59 unrelated healthy subjects for DQB1 alleles (only 59 subjects were typed for both DRB1 and DQB1). All cases in the study were assessed by thorough history taking, physical examination and laboratory investigations that included complete blood count, renal function tests, liver function tests, serum uric acid and HLA typing. Patients and controls were typed for HLA class II DRB1 and DQB1 alleles using INNO-LIPA reverse hybridization line probe assay (Innogenetic, Belgium).

RESULTS

HLA-DRB1 *0403 and *1301 and HLA-DQB1 *0501,* 0201 and *0301 were significantly increased in patients with NHL when compared with control; whereas HLA-DRB1 *1302 and HLA-DQB1 *0502 and *0602 were significantly decreased when compared with control. In patients with HD, HLA-DRB1 *0403 and *1202 and HLA-DQB1 *0604, *0201 and *0203 were significantly increased when compared with control.

CONCLUSIONS

(1) The susceptibility to NHL is related to HLA-DRB1 *0403 and *1301 and HLA-DQB1 *0501,* 0201 and *0301. (2) The susceptibility to HD is related to HLA-DRB1 *0403 and *1202 and HLA-DQB1 *0604, *0201 and *0203. (3) HLA-DRB1 *1302 and HLA-DQB1 *0502 and *0602 may confer protection to NHL. (4) Different HLA alleles may have a role in patients with both groups of lymphoma and further study is needed to better define the possible prognostic value of different HLA associations in patients with lymphomas regarding increased risk in the presence of certain HLA alleles and the possibility for treatment modifications in the future based on the presence or absence of certain HLA alleles.

L and E selectins in acute myeloid leukemia: expression, clinical relevance and relation to patient outcome

The aim of this study was to assess circulating soluble L (sL) and soluble E (sE) selectins adhesion molecules in acute myeloid leukemia (AML) blasts in order to evaluate their clinical significance. Fifty patients with AML (4 M0, 8 M1, 16 M2, 5 M3, 7 M4, 6 M5, 4 M6) were included in this study. sL and sE selectins were evaluated at diagnosis, remission and in relapsed patients; whole membrane expression of L and E selectins by AML blast was investigated only at diagnosis. In addition, 15 normal persons were studied as a control group. sL and sE selectins were significantly higher in AML patients at diagnosis when compared to controls (P<0.01), but less at remission (P<0.01). Furthermore, elevated sL and sE selectin levels were detected in patients with AML at relapse. sE and sL selectins were significantly higher in AML patients with extramedullary infiltration as compared to patients without extramedullary disease (P<0.001). Membrane expression of L selectin was positive in 20% of AML patients. However, none of the patients showed significant E selectin expression. Patients with higher sE and sL selectins at diagnosis have high probability of relapse compared to those with normal levels (P<0.01 and <0.001, respectively). The overall relapse predictability of sE and sL selectins was 84%. Moreover, patients with higher sE and sL selectins levels had shorter event free survival than patients with lower levels (P<0.001 for both). The overall mortality prediction using sE, sL, and cellular L selectin was 96%.

IN CONCLUSION

(1) AML blast cell express and release sL selectins but not sE selectin, (2) sE and sL selectins and cellular L selectin may be useful prognostic markers in evaluating AML patients at diagnosis.

Studies of peripheral blood T lymphocytes in assessment of disease activity in rheumatic fever

The study included three groups of children: (a) 38 with active rheumatic fever (ARF) and active carditis; 21 seen during their first attack and 17 during recurrence of activity, (b) 47 with inactive rheumatic fever (IARF); the period since activity was less than 3 years in 31 cases and more than 3 years in 16 cases. Using monoclonal antibodies and T lymphocyte blast transformation induced by PHA, we found: (1) low total T lymphocytes, helper-inducer cells and helper-inducer/suppressor-cytotoxic ratio which persisted for years; and (2) reduced lymphoblast transformation in active disease.

Enhanced response to the induction of sister chromatid exchange by gamma radiation in neurofibromatosis

The study included 8 unrelated patients with neurofibromatosis, and 10 unrelated normal and healthy persons as controls. Whole blood samples were divided into plastic T flasks and exposed at room temperature to gamma rays. The radiation dose was 36 rad/minute, and the doses delivered were 0, 75, 150 and 300 rad. The lymphocytes were cultured in (RPMI) 1640 tissue culture medium and autologous serum (20%). Phytohemagglutinin and bromodeoxyuridine (Brdu) (10 microM) were added at initiation of culture and harvesting was done 64 to 68 hours after culture initiation. Slides were coded, differential staining was done, and sister chromatid exchanges (SCEs) and aberrations (gaps, breaks, dicentrics, fragments and minutes) were counted. In the controls no significant increase in frequency of SCE has been found (P greater than 0.5). In the patients, the frequencies significantly increased with the increase of dose of irradiation (P less than 0.001). Furthermore, after irradiation, the incidence of gaps, breaks, and dicentrics were significantly increased in patients compared with controls. Moreover, the incidence increased with the increase in the dose of radiation. The results are discussed with a conclusion that the results add to the indication of a genetic predisposition to develop cancer in neurofibromatosis patients.

HLA-antigens in Guillain-Barré syndrome

A microlymphocytotoxicity test determined serologically the frequency of HLA antigens in 32 patients with Guillain-Barré syndrome and in 234 healthy control subjects. The results demonstrated significantly increased frequencies of A3 and B8. The relative risk was estimated to be 9.6 and 4.6 for the A3 and B8 antigens, respectively. Study of the gametic association revealed weak positive linkage disequilibrium and biological association. The results are discussed, and it is concluded that the aberrant genetic make-up of the patients makes them more susceptible to develop the syndrome after exposure to the environmental factor(s).

HLA antigens and acute rheumatic fever: evidence for a recessive susceptibility gene linked to HLA

From 60 probands with acute rheumatic fever (ARF), 19 multiplex families segregating for ARF were ascertained. The parents and rheumatic and normal sibs of the probands in these 19 families were also studied. HLA typing using the microlymphocytotoxic assay was then performed on the 60 unrelated probands, the multiplex families, and 234 unrelated controls using 23 antigens from the HLA-A and -B loci. The controls lacked a past history of ARF and were from the same geographic locality. Calculations of relative risk demonstrate an increase of HLA-B5 antigen in the 60 patients, but the result might not be significant from the point of view of multiple comparisons. Nevertheless, affected sib pairs from the multiplex families show 93% concordance for both or one HLA haplotype. A formal linkage analysis demonstrates that a recessive etiology is most likely (lod score of 3.3) with approximately 68% of cases being due to a gene closely linked to HLA and in linkage disequilibrium with HLA-B5. The remaining 32% of cases are due to other familial factors such as polygenic inheritance or common environmental factors. The results confirm a strong genetic predisposition to ARF and its heterogeneous nature in families.