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Biomedical subjects

O Sanal

Publications and source records attributed to O Sanal.

At least 37 records · Page 2Linked to original sources
PubMed1999

Impaired IgG antibody production to pneumococcal polysaccharides in patients with ataxia-telangiectasia.

Various factors seem to be etiologic in the susceptibility to sinopulmonary infections in ataxia-telangiectasia (A-T) patients, i.e., low serum and salivary IgA, low serum IgG2, and even aspiration of saliva. S. pneumoniae is a common pathogen responsible from pulmonary infections and impaired antibody response to polysaccharide antigens is seen in patients with IgG2 and IgA deficiency as well as patients with CVID and WAS. We studied IgG-type antibody production to six pneumococcal serotypes in 29 A-T patients by ELISA before and 3-4 weeks after pneumococcal vaccine. The response was considered positive when the antibody titer was >10 U/ml but weak when the titer was 10-20 U/ml. Twenty-two of 29 (76%) patients did not respond to any of the serotypes, 5 (17%) showed a positive response to one serotype, 1 (3.4%) to two serotypes, and 1 (3.4%) to four serotypes. With conversion to gravimetric units (ng IgG/ml) and >1800 ng/ml (300 ng Ab N/ml) considered a positive response, 5 of 29 (17.2%) patients showed a positive response (300 ng ab N/ml) to two or fewer serotypes. All patients tested produced IgG antibody to tetanus toxoid. Sixteen of 27 (59.3%) patients had low IgG2 and four (14.8%) had low IgG3 levels, while 18 (62.1%) of 29 patients had low serum IgA. No correlation was found either between serum Ig isotype levels and antipolysaccharide antibody response or between susceptibility to infection and antibody production. The mechanism responsible for disturbed antipolysaccharide (TI-2 antigen) antibody production in patients with A-T needs to be investigated. It may provide additional information on the function of the ATM gene product and be helpful in clarifying the role of B cells and contribution of T cells in TI-2 responses.

Adolescent↗
PubMed1999

Successful bone marrow transplantation in a case of Griscelli disease which presented in accelerated phase with neurological involvement.

Griscelli disease (GD) is a rare disorder characterized by pigment dilution, immunodeficiency and occurrence of accelerated phase consisting of hemophagocytosis, pancytopenia and neurological manifestations. Allogeneic BMT in the early period is an important modality of treatment for GD. We carried out an alloBMT from an HLA-identical sibling donor on a 4-year-old girl who presented in accelerated phase with neurological manifestations including convulsions, strabismus, severe dysarthria, ataxia and clonus. She was treated with etoposide, methylprednisolone and intrathecal methotrexate for 8 weeks and underwent alloBMT after receiving a conditioning regimen including ATG (rabbit, 10 mg/kg x 5 days), Bu/Cy. 8 x 108/kg nucleated bone marrow cells were given. Engraftment occurred early and the post-BMT period was uneventful. Currently, she is at 18 months post BMT with sustained engraftment and with a normal neurological examination except for minimal clonus. Long-term follow-up will determine the prognosis regarding the neurological findings.

Bone Marrow Transplantation↗
PubMed1999

Splicing defects in the ataxia-telangiectasia gene, ATM: underlying mutations and consequences.

Mutations resulting in defective splicing constitute a significant proportion (30/62 [48%]) of a new series of mutations in the ATM gene in patients with ataxia-telangiectasia (AT) that were detected by the protein-truncation assay followed by sequence analysis of genomic DNA. Fewer than half of the splicing mutations involved the canonical AG splice-acceptor site or GT splice-donor site. A higher percentage of mutations occurred at less stringently conserved sites, including silent mutations of the last nucleotide of exons, mutations in nucleotides other than the conserved AG and GT in the consensus splice sites, and creation of splice-acceptor or splice-donor sites in either introns or exons. These splicing mutations led to a variety of consequences, including exon skipping and, to a lesser degree, intron retention, activation of cryptic splice sites, or creation of new splice sites. In addition, 5 of 12 nonsense mutations and 1 missense mutation were associated with deletion in the cDNA of the exons in which the mutations occurred. No ATM protein was detected by western blotting in any AT cell line in which splicing mutations were identified. Several cases of exon skipping in both normal controls and patients for whom no underlying defect could be found in genomic DNA were also observed, suggesting caution in the interpretation of exon deletions observed in ATM cDNA when there is no accompanying identification of genomic mutations.

Ataxia Telangiectasia↗
PubMed1998

Identification of ATM mutations using extended RT-PCR and restriction endonuclease fingerprinting, and elucidation of the repertoire of A-T mutations in Israel.

Ataxia-telangiectasia (A-T) is an autosomal recessive disorder characterized by neurodegeneration, immunodeficiency, cancer predisposition, and radiation sensitivity. The responsible gene, ATM, has an extensive genomic structure and encodes a large transcript with a 9.2 kb open reading frame (ORF). A-T mutations are extremely variable and most of them are private. We streamlined a high throughput protocol for the search for ATM mutations. The entire ATM ORF is amplified in a single RT-PCR step requiring a minimal amount of RNA. The product can serve for numerous nested PCRs in which overlapping portions of the ORF are further amplified and subjected to restriction endonuclease fingerprinting (REF) analysis. Splicing errors are readily detectable during the initial amplification of each portion. Using this protocol, we identified 5 novel A-T mutations and completed the elucidation of the molecular basis of A-T in the Israeli population.

Ataxia Telangiectasia↗
PubMed1998

A case of chronic severe neutropenia: oral findings and consequences of short-term granulocyte colony-stimulating factor treatment.

Neutropenia is an absolute decrease in the number of circulating neutrophils in the blood which results in susceptibility to severe pyogenic infections. Various oral findings such as periodontitis, alveolar bone loss and ulceration may be seen in neutropenic patients. A case is presented of a 6 year old girl with chronic, probably congenital, severe neutropenia with frequent respiratory tract infections, recurrent oral ulcerations and significant periodontal break-down resembling prepubertal periodontitis. She was given granulocyte-colony stimulating factor (G-CSF) treatment which resulted in an increase in granulocyte count within two weeks and resolution of the neutropenic ulceration. It is suggested that G-CSF together with dental care regimens is a promising treatment model in chronic severe neutropenia cases presenting with oral manifestations.

Aggressive Periodontitis↗
PubMed1997

Development of systemic lupus erythematosus in a patient with selective complete C1q deficiency.

UNLABELLED: A 7-year-old male with recurrent erythematous and desquamated skin lesions and respiratory infections was diagnosed as selective complete C1q deficiency following detailed studies of the complement system. His asymptomatic sister also had selective complete C1q deficiency. During a follow up period of 3 years, his skin lesions persisted, he suffered from recurrent bronchopneumonias and glomerulonephritis developed. Renal function deteriorated with the appearance of anti-DNA antibodies. Renal biopsy was consistent with systemic lupus erythematosus. The patient was treated with immunosuppressive drugs, but died of renal failure. It is postulated that in this patient defective clearance of antigen-antibody complexes by the reticulo-endothelial system resulted in progressive renal disease as observed in other complement deficiencies. A retrospective molecular study disclosed a point mutation in the ClqA chain gene in a heterozygous state in parents and two siblings; in a homozygous state in the asymptomatic sister. The reason why some individuals with this defect are asymptomatic is not known at present. Diagnosis of heterozygotes by molecular studies is extremely important to give genetic counselling to the family. CONCLUSION: Patients with recurrent infections, erythematous desquamative skin lesions, malar rash and oral mucosal involvement should be screened for complement C1q deficiency.

Blood Protein Disorders↗
PubMed1997

Clinical spectrum of X-linked hyper-IgM syndrome.

We report the clinical and immunologic features and outcome in 56 patients with X-linked hyper-IgM syndrome, a disorder caused by mutations in the CD40 ligand gene. Upper and lower respiratory tract infections (the latter frequently caused by Pneumocystis carinii), chronic diarrhea, and liver involvement (both often associated with Cryptosporidium infection) were common. Many patients had chronic neutropenia associated with oral and rectal ulcers. The marked prevalence of infections caused by intracellular pathogens suggests some degree of impairment of cell-mediated immunity. Although lymphocyte counts and in vitro proliferation to mitogens were normal, a defective in vitro proliferative response to antigens was observed in some patients, and additional defects of cell-mediated immunity may be presumed on the basis of current knowledge of CD40-ligand function. All patients received regular infusions of immunoglobulins. Four patients underwent liver transplantation because of sclerosing cholangitis, which relapsed in there. Three patients underwent bone marrow transplantation. Thirteen patients (23%) died of infection and/or liver disease. X-linked hyper-IgM syndrome, once considered a clinical variant of hypogammaglobulinemia, is a severe immunodeficiency with significant cellular involvement and a high mortality rate.

Bone Marrow Transplantation↗
PubMed1997

Griscelli disease maps to chromosome 15q21 and is associated with mutations in the myosin-Va gene.

Griscelli disease (OMIM 214450) is a rare autosomal recessive disorder characterized by pigmentary dilution, variable cellular immunodeficiency and onset of acute phases of uncontrolled lymphocyte and macrophage activation, leading to death in the absence of bone-marrow transplantation. The pigmentary dilution is characterized by a diffuse skin pigmentation, silvery hair, large clumps of pigments in the hair shafts (Fig. 1) and an accumulation of melanosomes in melanocytes, with abnormal transfer of the melanin granules to the keratinocytes. Immunological abnormalities are characterized by absent delayed-type cutaneous hypersensitivity and an impaired natural-killer cell function. A similar disorder has been described in the dilute lethal mouse--which, however, differs by the occurrence of a severe neurological disorder. The dilute locus encodes myosin-Va, a member of the unconventional myosin family. Myosins bind actin and produce mechanical force through ATP hydrolysis. Some members of this family are thought to participate in organelle-transport machinery. Because of the phenotype resulting in the dilute mouse and because of their potential role in intracellular transport, unconventional myosin-encoding genes were regarded as candidate genes for Griscelli disease. Here we report that the Griscelli disease locus co-localizes on chromosome 15q21 with the myosin-Va gene, MYO5a, and that mutations of this gene occur in two patients with the disease. Griscelli disease is therefore a human equivalent of dilute expression in the mouse.

Albinism↗
PubMed1996

Human T cell repertoire generation in the absence of MHC class II expression results in a circulating CD4+CD8- population with altered physicochemical properties of complementarity-determining region 3.

In this study, we have investigated the impact of deficient MHC class II expression on the use of TCRBV6 and TCRBJ gene elements, and on the pattern of amino acid incorporation exhibited in the N1-D-N2 segments of the third complementarity-determining region (CDR3) of these TCRBV6 rearrangements. To this end, we have analyzed circulating T cells from three, nonrelated MHC class II-deficient (bare lymphocyte syndrome (BLS)) patients and three MHC class II-expressing family members. The patients and healthy controls exhibited similar, nonrandom usage profiles of TCRBV6 and TCRBJ gene elements in both the CD4+CD8- and the CD4-CD8+ subsets of peripheral blood T cells. No statistically significant differences between patients and controls were detected in the length of CDR3, or in the amount of non-germline modification at the sites of recombination. However, detailed analysis of the TCRBV6 rearrangements derived from the CD4+CD8- subsets from the BLS patients revealed patterns of amino acid incorporation into the N1-D-N2 region of CDR3 that resulted in altered charge and hydropathicity properties of the presumed Ag binding site. In this way, we have been able to demonstrate that human T cell repertoire development in the absence of MHC class II expression results in a circulating CD4+CD8- T cell population bearing TCRs with altered CDR3 profiles. Such altered profiles are likely to be a direct reflection of the lack of MHC class II-mediated selection processes in these BLS patients.

Amino Acid Sequence↗
PubMed1996

Predominance of null mutations in ataxia-telangiectasia.

Ataxia-telangiectasia (A-T) is an autosomal recessive disorder involving cerebellar degeneration, immunodeficiency, chromosomal instability, radiosensitivity and cancer predisposition. The responsible gene, ATM, was recently identified by positional cloning and found to encode a putative 350 kDa protein with a Pl 3-kinase-like domain, presumably involved in mediating cell cycle arrest in response to radiation-induced DNA damage. The nature and location of A-T mutations should provide insight into the function of the ATM protein and the molecular basis of this pleiotropic disease. Of 44 A-T mutations identified by us to date, 39 (89%) are expected to inactivate the ATM protein by truncating it, by abolishing correct initiation or termination of translation, or by deleting large segments. Additional mutations are four smaller in-frame deletions and insertions, and one substitution of a highly conserved amino acid at the Pl 3-kinase domain. The emerging profile of mutations causing A-T is thus dominated by those expected to completely inactivate the ATM protein. ATM mutations with milder effects may result in phenotypes related, but not identical, to A-T.

Amino Acid Sequence↗
PubMed1996

IgG subclasses in children with recurrent respiratory tract infections in an allergy practice.

Isolated or combined deficiencies of immunoglobulin G (IgG) subclasses have been recognized in children with recurrent infections. In our allergy practice, there are a subset of children with recurrent respiratory tract infections. To investigate the presence of immunoglobulin G subclass deficiency (IgGSD), 60 children with atopy and 14 children without atopy suffering from recurrent respiratory tract infections were studied in an attempt to determine whether atopy is associated with a certain IgG subclass pattern. Ten atopic children were found to have isolated or combined IgG subclass deficiencies: one with IgG1, two with IgG2, four with IgG3 and three children had IgG2-IgG3. Neither IgG subclass concentration nor the frequency of children with high or low IgG subclasses showed any difference between atopic and non-atopic groups. Except for a week correlation with IgG3, no correlation existed between IgE and other IgG subclasses. It was concluded that childhood respiratory diseases complicated by recurrent respiratory tract infections may be associated with IgG subclass deficiencies. Although there have been reports noting some IgG subclass patterns in atopic disorders, in the present study, no distinctive feature between atopics and non-atopics with respect to IgG subclass concentrations and patterns was observed.

Adolescent↗
PubMed1996

Dyskeratosis congenita: unusual onset with isolated neutropenia at an early age.

A 3.5 year old male patient with dyskeratosis congenita (DC) presented at the age of 13 months with isolated neutropenia preceding characteristic skin findings. The average absolute neutrophil count of 500/mm3 persisted without the presence of anemia or thrombocytopenia during the follow up. Neutropenia responded to granulocyte-colony stimulating factor (G-CSF) at a dose of 10 micrograms/kg per day. Immunologic findings were normal as was the chromosomal stability and sister chromatid exchange.

Child, Preschool↗
PubMed1996

An infant with severe leucocyte adhesion deficiency.

A case of severe leucocyte adhesion deficiency occurred in a 6 1/2-month-old boy whose parents were first-degree cousins. Evidence of the disease first became apparent with the late separation of the umbilical cord on the 20th day and with the later development of omphalitis. The most specific finding was the very low levels of CD18 and CD11, 0.44 and 0.15%, respectively. The boy died from sepsis which occurred as an extension of necrotic lesions on the ear and in the gluteal area.

Abscess↗
PubMed1996

Homozygous C2 deficiency: association with defective alternative pathway function and immunoglobulin deficiency.

Deficiency in the second component of complement (C2) is the most common homozygous complement deficiency. While approximately half of the affected individuals are apparently healthy, C2 deficiency may be associated with autoimmune diseases and rarely increased susceptibility to infection. We report 5 patients who had homozygous type I C2 deficiency in two families. Three of them suffered from frequent infections. These symptomatic patients had additional risk factors; the index cases in the first and the second family had IgG2 deficiency and IgA deficiency, respectively, and alternative complement pathway hemolytic activity was also low in both of them and in the sibling of the first index case. These results emphasize the probable role of other immunologic defects in the clinical presentation of C2 deficiency.

Child↗