Nevin Yalman

Spectrum of perforin gene mutations in familial hemophagocytic lymphohistiocytosis.

Familial hemophagocytic lymphohistiocytosis (FHL) is an autosomal recessive disease of early childhood characterized by nonmalignant accumulation and multivisceral infiltration of activated T lymphocytes and histiocytes (macrophages). Cytotoxic T and natural killer (NK) cell activity is markedly reduced or absent in these patients, and mutations in a lytic granule constituent, perforin, were recently identified in a number of FHL individuals. Here, we report a comprehensive survey of 34 additional patients with FHL for mutations in the coding region of the perforin gene and the relative frequency of perforin mutations in FHL. Perforin mutations were identified in 7 of the 34 families investigated. Six children were homozygous for the mutations, and one patient was a compound heterozygote. Four novel mutations were detected: one nonsense, two missense, and one deletion of one amino acid. In four families, a previously reported mutation at codon 374, causing a premature stop codon, was identified, and, therefore, this is the most common perforin mutation identified so far in FHL patients. We found perforin mutations in 20% of all FHL patients investigated (7/34), with a somewhat higher prevalence, approximately 30% (6/20), in children whose parents originated from Turkey. No other correlation between the type of mutation and the phenotype of the patients was evident from the present study. Our combined results from mutational analysis of 34 families and linkage analysis of a subset of consanguineous families indicate that perforin mutations account for 20%-40% of the FHL cases and the FHL 1 locus on chromosome 9 for approximately 10%, whereas the major part of the FHL cases are caused by mutations in not-yet-identified genes.

Characterization of PRF1, STX11 and UNC13D genotype-phenotype correlations in familial hemophagocytic lymphohistiocytosis

Familial hemophagocytic lymphohistiocytosis (FHL) is a rare autosomal recessive lethal condition characterized by fever, cytopenia, hepatosplenomegaly and hemophagocytosis. The hallmark of FHL is defect apoptosis triggering and lymphocyte cellular cytotoxicity. Thus far three disease‐causing genes (PRF1, UNC13D, STX11) have been identified. We performed a genotype‐phenotype study in a large, multi‐ethnic cohort of 76 FHL patients originating from 65 unrelated families. Biallelic mutations in PRF1, UNC13D and STX11 were demonstrated in 13/74 (18%), 6/61 (10%) and 14/70 (20%) patients, respectively. In 27/60 (45%) patients analyzed for all three genes, no molecular diagnosis was established. STX11 mutations were most common in Turkish families (7/28, 25%), whereas in Middle East families, PRF1 mutations were most frequent (6/13, 46%). No biallelic mutation was identified in most families of Nordic origin (13/14, 93%). Patients carrying PRF1 mutations had higher risk of early onset (age <6 months) compared to patients carrying STX11 mutations [adjusted odds ratio 8·23 (95% confidence interval [CI] = 1·20–56·40), P = 0·032]. Moreover, patients without identified mutations had increased risk of pathological cerebrospinal fluid (CSF) at diagnosis compared to patients with STX11 mutations [adjusted odds ratio 26·37 (CI = 1·90–366·82), P = 0·015]. These results indicate that the disease‐causing mutations in FHL have different phenotypes with regard to ethnic origin, age at onset, and pathological CSF at diagnosis.

A male-specific increase in the HLA-DRB4 (DR53) frequency in high-risk and relapsed childhood ALL

Previous studies reported significant HLA-DR associations with various leukemias one of which is with HLA-DRB4 (DR53) family in male patients with childhood ALL. We have HLA-DR-typed 212 high-risk or relapsed patients with childhood (n=114) and adult (n=98) ALL and a total of 250 healthy controls (118 children, 132 adult) by PCR-SSP analysis. The members of the HLA-DRB3 (DR52) family were underrepresented in patients most significantly for HLA-DRB1*12 (P=0.0007) and HLA-DRB1*13 (P=0.0001). In childhood ALL, the protective effect of DRB3 was evident in homozygous form (P=0.001). The DRB4 marker frequency was increased in males with childhood ALL (67.4%) compared to age- and sex-matched controls (42.1%, P=0.003) and female patients (35.7%, P=0.004). Besides being a general marker for increased susceptibility to childhood ALL in males, HLA-DRB4 is over-represented in high-risk patients. These results further suggest that the HLA system is one of the components of genetic susceptibility to leukemia but mainly in childhood and in boys only.

Is AML1/ETO gene expression a good prognostic factor in pediatric acute myeloblastic leukemia?

To assess the clinical significance of AML1/ETO gene detected by nested reverse transcriptase polymerase chain reaction, the outcome of 7 patients with acute myeloblastic leukemia between 3 and 14 years of age were presented. All patients had complete remission (CR) at the end of induction (AMLMRC 10 protocol) and 4 underwent unpurged autologous, 2 allogeneic (from matced siblings) non-T-cell-depleted bone marrow transplantations (BMT) in first CR. One patient died due to allogeneic BMT-related complications, and 4 patients relapsed at 13, 17, 18, and 26 months. Only one patient achieved second CR. All relapsed patients died between 18 and 36 months with resistant disease (n = 3) or infection during salvage chemotherapy (n = 1). Two patients who had autologous BMT are alive and disease free at 44 and 50 months. Although statistical significance could not be shown, event-free survival and overall survival rates of AML1/ETO-positive patients (28.57 and 28.57% , respectively) at 3.5 years were even lower than those of AML1/ETO-negative patients. The results confirm some previous reports that AML1/ETO gene in children and adolescents is not a favorable prognostic factor.

Reactivation: A severe problem in familial hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a rare disorder with principal clinical features of fever and splenomegaly accompanied by pancytopenia, hypertriglyceridemia and/or hypofibrinogenemia with histological evidence of hemophagocytosis.1 Familial hemophagocytic lymphohistiocytosis (FHLH) shows an autosomal recessive mode of inheritance. When there is evidence of concurrent infection, the disease is often called infection-associated hemophagocytic lymphohistiocytosis (IAHS). The onset of FHLH and bouts of the disease may also be triggered by infections.2 We report our experience with six FHLH patients over a 2-year period that focuses on the variability of clinical features, overlap between familial and sporadic cases and the problem of reactivation.

SUCCESSFULL TREATMENT OF CHILDHOOD REFRACTORY CHRONIC IMMUNE THROMBOCYTOPENIC PURPURA WITH CYCLOSPORINE A 168

SUCCESSFULL TREATMENT OF CHILDHOOD REFRACTORY CHRONIC IMMUNE THROMBOCYTOPENIC PURPURA WITH CYCLOSPORINE A 168

HEPATIC ABNORMALITIES IN THALASEMIA MAJOR 83

Hepatic abnormalities of Thalasemic patients due to iron overload and hepatotropic viruses were evaluated. The study was undertaken between October 1993 and October 1994 in 29 patients (12 boys, 17 girls) with a median age of 13 years (range 3-22 years). Patients were transfused regularly to maintain a hemoglobin value of 10 g/dl or higher. All except a 3 year old girl were on subcutan desferroxamin therapy (40-60 mg/kg/day, 5 days/week). 62% of patients were splenectomised. Seropositivity was 82.76% for Hepatitis B virus 68.9% anti-HBs positive, 3.5% chronic HBsAg carrier) whereas 27.5% for Hepatitis C virus. In anti-HCV (+) group serum ALT levels were higher than anti-HCV(-) group, 114.75±67.75 and 67.61± 46.95, respectively (p:0.042). Mean serum ferritin level was 7145.13± 4938.75 ng/ml (range 224-20.000) and had a positive correlation with age, total number of transfusions, serum AST, ALT and total bilirubin but no correlation with GGT, D.Bilirubin, Alkaline phosphatase, PT, PTT, iron and iron binding capacity. 10 patients underwent liver biopsy. Biopsies revealed 1 inactive cirrhosis, 1 chronic persistant hepatitis, 4 portal fibrosis and hemochromatosis in all specimen. As a conclusion, Hepatitis B seropositivity is high among Thalasemic children. Iron chelating agent is efficient but can not prevent iron overload and liver damage completely. We recommend early vaccination of all Thalasemic children for Hepatitis B and screening of blood donors with more sensitive methods.