A reliable screening test to identify adult carriers of the (--SEA) alpha zero-thalassemia deletion. Detection of embryonic zeta-globin chains by enzyme-linked immunosorbent assay

Homozygous (--SEA) alpha zero-thalassemia deletion, the cause of up to 80% of fetal hydrops in Southeast Asia, is encountered in many other countries. Heterozygous carrier rates of the deletion in Southeast Asian populations range from 4% to 14%. The laboratory screening for adult carriers of (--SEA) and other alpha zero-thalassemia deletions currently rests primarily with microscopic detection of hemoglobin H inclusion bodies within erythrocytes (Hb H screen). This test is laborious and observer dependent and has poor sensitivity. We assessed a colorimetric enzyme-linked immunosorbent assay (ELISA) to detect embryonic zeta-globin chains in adult hemolysates as an alternative to detect (--SEA) alpha zero-thalassemia deletion carriers. Blood samples from 221 adults with a mean corpuscular volume less than 80 micron 3 (80 fL) were studied prospectively by currently accepted hemoglobin screening tests and ELISA. Suspected cases of alpha-thalassemia were confirmed by DNA-based diagnostics. ELISA was highly sensitive (1.0) and specific (0.94) for the detection of adult carriers of (--SEA) alpha zero-thalassemia deletion. The hemoglobin H screen had a sensitivity of 0.47 and specificity of 0.99. The zeta-globin ELISA proved simple to perform, rapid, and applicable to high volume or population-based screening programs.

beta-thalassemia intermedia caused by compound heterozygosity for Hb Malay (beta codon 19 AAC-->AGC; asn-->Ser) and codons 41/42 (-CTTT) beta(0)-thalassemia mutation

We report a case of beta-thalassemia intermedia caused by compound heterozygosity for hemoglobin (Hb) Malay and codon 41/42 (-CTTT) beta(0)-thalassemia mutation in a 38-year-old Chinese woman. This patient has long-standing anemia with a baseline Hb level of around 70 g/L. She worked as a full-time cashier and had not required regular blood transfusions. Nevertheless, she had splenomegaly necessitating splenectomy, cholelithiasis, and iron overload. This case illustrates the varied phenotypic expression associated with compound heterozygosity for Hb Malay and other beta-thalassemia mutations. Since Hb Malay migrates as Hb A on electrophoresis and chromatography, this variant Hb mutation ought to be included in the differential diagnosis for beta-thalassemia major or intermedia patients of Southeast Asian descent who are reported to have Hb A on the basis of Hb analysis. The possible presence of this mutation should also be considered in appropriate cases for genetic counseling in couples at risk of conceiving fetuses with beta-thalassemia major or intermedia.

Hla-DR2-restricted responses to proteolipid protein 95-116 peptide cause autoimmune encephalitis in transgenic mice

In multiple sclerosis (MS) patients who carry the Class II major histocompatibility (MHC) type HLA-DR2, T cells specific for amino acids 95-116 in the proteolipid protein (PLP) are activated and clonally expanded. However, it remains unclear whether these autoreactive T cells play a pathogenic role or, rather, protect against the central nervous system (CNS) damage. We have addressed this issue, using mice transgenic for the human MHC class II region carrying the HLA-DR2 (DRB1* 1502) haplotype. After stimulating cultured lymph node cells repeatedly with PLP95-116, we generated 2 HLA-DR2-restricted, PLP95-116-specific T-cell lines (TCLs) from the transgenic mice immunized with this portion of PLP. The TCLs were CD4+ and produced T-helper 1 (Th1) cytokines in response to the peptide. These TCLs were adoptively transferred into RAG-2/2 mice expressing HLA-DR2 (DRG1* 1502) molecules. Mice receiving 1 of the TCLs developed a neurological disorder manifested ataxic movement without apparent paresis on day 3, 4, or 5 after cell transfer. Histological examination revealed inflammatory foci primarily restricted to the cerebrum and cerebellum, in association with scattered demyelinating lesions in the deep cerebral cortex. These results support a pathogenic role for PLP95-116-specific T cells in HLA-DR2+ MS patients, and shed light on the possible correlation between autoimmune target epitope and disease phenotype in human CNS autoimmune diseases.

Chronic stress induces impairment of spatial working memory because of prefrontal dopaminergic dysfunction

Although the mechanism responsible for cognitive deficits in stress-related neuropsychiatric disorders has been obscure, prefrontal cortical (PFC) dopaminergic dysfunction is thought to be involved. In animals, the mesoprefrontal dopaminergic system is particularly vulnerable to stress, and chronic stress induces working memory impairment. However, the relation between the working memory impairment and altered dopaminergic activity in chronically stressed rats is unclear. Furthermore, the change of dopaminergic activity in the PFC induced by stress is thought to express as a stress response, not as a disorder of organic function. We have previously reported that chronic stress administered by water immersion and restraint for 4 weeks induces a organic disorder such as hippocampal neuronal degeneration. We therefore examined whether chronically stressed (4 weeks) and recovered (10 d) rats show a working memory impairment caused by reduced dopamine (DA) transmission in the PFC, as suspected in the neuropsychiatric disorders. The stress impaired the spatial working memory evaluated by T-maze task and induced a marked reduction of DA transmission concomitant with an increase in DA D1 receptor density in the PFC. This memory impairment was sufficiently ameliorated by intra-PFC infusion of 10 ng SKF 81297, a D1 receptor-specific agonist. Pretreatment with intraperitoneal injection of 20 microgram/kg SCH 23390, a D1 receptor antagonist, reversed the SKF 81297 response. These results indicate that chronic stress induces working memory impairment through a D1 receptor-mediated hypodopaminergic mechanism in the PFC. These findings provide important information for understanding of the mechanisms underlying PFC dysfunction in stress-related neuropsychiatric disorders.

Ermap, a gene coding for a novel erythroid specific adhesion/receptor membrane protein

Ermap (erythroid membrane-associated protein), a gene coding for a novel transmembrane protein produced exclusively in erythroid cells, is described. It is mapped to murine Chromosome 4, 57 cM distal to the centromere. The initial cDNA clone was isolated from a day 9 murine embryonic erythroid cell cDNA library. The predicted peptide sequence suggests that ERMAP is a transmembrane protein with two extracellular immunoglobulin folds, as well as a highly conserved B30.2 domain and several phosphorylation consensus sequences in the cytoplasmic region. ERMAP shares a high homology throughout the entire peptide with butyrophilin, a glycoprotein essential for milk lipid droplet formation and release. A GFP-ERMAP fusion protein was localized to the plasma membrane and cytoplasmic vesicles in transiently transfected 293T cells. Northern blot analysis and in-situ hybridization demonstrated that Ermap expression was restricted to fetal and adult erythroid tissues. ERMAP is likely a novel adhesion/receptor molecule specific for erythroid cells.

PCR-based diagnosis of the Filipino (--(FIL)) and Thai (--(THAI)) alpha-thalassemia-1 deletions

In southeast Asia, the carrier frequency of two-gene alpha-thalassemia deletions is quite high, ranging from 4% to 14% depending on the population. The most common alpha-thalassemia-1 deletion is the so-called southeast Asian deletion (--(SEA)). In addition, a significant proportion of cases involve two other deletions, the Filipino (--(FIL)) and Thai (--(THAI)) deletions. In this report, we identify the deletion breakpoints for the (--(FIL)) and (--(THAI)) deletions, and describe PCR-based protocols for rapid and reliable DNA diagnosis of these deletions.

Embryonic hemoglobins are expressed in definitive cells

Human embryonic zeta and epsilon globin chains are synthesized in yolk sac-derived primitive erythroid cells, and decrease rapidly during definitive erythropoiesis. Examination of zeta and epsilon globin expression at the cellular level using dual-color immunofluorescence staining with specific monoclonal antibodies showed that embryonic globin proteins are present in definitive erythroid cells. More than half of fetal erythrocytes were positive for zeta and approximately 5% for epsilon globin. Approximately one third of newborn red blood cells were zeta-positive and less than 1% epsilon-positive. Adult erythrocytes did not have embryonic globins. Erythroblasts that developed in liquid cultures also contained embryonic globin in amounts which declined with ontogenic age, and the proportion of positive cells in vitro was less than in the comparable erythrocytes that developed in vivo. Thus, embryonic globin chains are synthesized in definitive erythroid cells and decrease with ontogeny. Modulation of embryonic globin gene expression is not solely due to a switch from primitive to definitive erythropoiesis.

Transgenic mice with Alzheimer presenilin 1 mutations show accelerated neurodegeneration without amyloid plaque formation

Familial Alzheimer disease mutations of presenilin 1 (PS-1) enhance the generation of A beta1-42, indicating that PS-1 is involved in amyloidogenesis. However, PS-1 transgenic mice have failed to show amyloid plaques in their brains. Because PS-1 mutations facilitate apoptotic neuronal death in vitro, we did careful quantitative studies in PS-1 transgenic mice and found that neurodegeneration was significantly accelerated in mice older than 13 months (aged mice) with familial Alzheimer disease mutant PS-1, without amyloid plaque formation. However, there were significantly more neurons containing intracellularly deposited A beta42 in aged mutant transgenic mice. Our data indicate that the pathogenic role of the PS-1 mutation is upstream of the amyloid cascade.

Both N-terminal and C-terminal fragments of presenilin 1 colocalize with neurofibrillary tangles in neurons and dystrophic neurites of senile plaques in Alzheimer's disease

Presenilin 1 (PS1) is a causative gene for chromosome 14-linked familial Alzheimer's disease. The gene product is known to be cleaved into N-terminal fragments (PS1-N) and C-terminal fragments (PS1-C). To understand the pathophysiological role of PS1, we conducted immunohistochemical studies using antibodies specific for PS1-N and PS1-C in sporadic Alzheimer's disease (AD). Both antibodies showed punctuate staining exclusively in neurons and their processes in both control and AD brains. PS1-N immunolabeling colocalized with neurofibrillary tangles (NFTs) in 36% of NFT-bearing neurons and with dystrophic neurites in 28% of senile plaques (SPs). PS1-C immunolabeling colocalized with dystrophic neurites in 70% of NFT-bearing SPs and with intraneuronal NFTs in 32% of NFT-bearing neurons. Both antibodies did not detect PHF-tau-positive neuropil threads and Abeta amyloid fibrils. The colocalization was also found in 33-38 % of NFT-bearing neurons in progressive supranuclear palsy. These results indicate that both PS1-N and PS1-C fragments are deposited in part of NFT-bearing neurons and dystrophic neurites in SPs; both are the pathologic hallmarks of AD.

Interleukin-3 and interleukin-3 receptors in the brain

We have previously demonstrated that interleukin 3 (IL-3) has a neurotrophic effect on central cholinergic neurons and have demonstrated the presence of IL-3 receptor (IL-3R)beta subunits in septal cholinergic neurons by reverse-transcribed polymerase chain reaction (RT-PCR) and immunohistochemistry. In order to confirm that the expressed IL-3R is functional, we conducted experiments to show an alpha subunit of IL-3R. The alpha subunit was clearly demonstrated by RT-PCR in the central cholinergic neuronal hybrid cell line SN6, but not in its mother cell line N18TG2, and the expression was slightly upregulated after IL-3 treatment. Choline acetyltransferase and vesicular acetylcholine transporter mRNAs were significantly increased in SN6 after treatment with IL-3. Immunohistochemically, IL-3R alpha-positive cells were mainly present in the medial septal and basal forebrain region, and the stained cells were similar to choline acetyltransferase-positive cells in shape and distribution. The IL-3R alpha-positive cells slightly increased two days after fimbria-fornix transection and decreased seven days after. These findings suggest that functional IL-3 receptors are expressed in the central cholinergic neurons and contribute to some physiological roles such as the differentiation and maintenance of these neurons.

Coinheritance of alpha-thalassemia-1 and hemoglobin E/beta zero-thalassemia: practical implications for neonatal screening and genetic counseling

Hemoglobin E (HbE), alpha-thalassemia, and beta-thalassemia are common among Southeast Asians and often occur in compound heterozygous states that complicate neonatal screening. We describe a kindred with alpha-thalassemia-1, HbE, and beta zero-thalassemia. The proband had HbE/beta zero-thalassemia, with severe anemia and failure to thrive. His father also had HbE/beta zero-thalassemia but had coinherited alpha-thalassemia-1 and was free of symptoms.

Access to a syllabus of human hemoglobin variants (1996) via the World Wide Web

Information on mutations in human hemoglobin is important in many efforts, including understanding the pathophysiology of hemoglobin diseases, developing therapies, elucidating the dynamics of sequence alterations inhuman populations, and dissecting the details of protein structure/function relationships. Currently, information is available on a large number of mutations and variants, but is distributed among thousands of papers. In an effort to organize this voluminous data set, two Syllabi have been prepared compiling succinct information on human hemoglobin abnormalities. In both of these, each entry provides amino acid and/or DNA sequence alterations, hematological and clinical data, methodology used for characterization, ethnic distribution, and functional properties and stability of the hemoglobin, together with appropriate literature references. A Syllabus of Human Hemoglobin Variants (1996) describes 693 abnormal hemoglobins resulting from alterations in the alpha-, beta-, gamma-, and delta-globin chains, including special abnormalities such as double mutations, hybrid chains, elongated chains, deletions, and insertions. We have converted this resource to an electronic form that is accessible via the World Wide Web at the Globin Gene Server (http://globin.cse.psu.edu). Hyperlinks are provided from each entry in the tables of variants to the corresponding full description. In addition, a simple query interface allows the user to find all entries containing a designated word or phrase. We are in the process of converting A Syllabus of Thalassemia Mutations (1997) to a similar electronic format.

De novo mutation of the beta-globin gene initiation codon (ATG-->AAG) in a Northern European boy

We present a case of beta-thalassemia intermedia involving a 13-year-old boy of Northern European descent. His mother, father and older sister have normal hematologic indices. Molecular studies demonstrate that the proband carries a novel mutation of the beta-globin gene initiation codon (ATG-->AAG) which should give rise to beta(0)-thalassemia trait. The possibility of non-paternity was excluded, indicating that the novel mutation was the result of a de novo event. A review of the literature indicates that mutations involving the beta-globin gene initiation codon can give rise to a more severe phenotype than is generally associated with most other beta(+) or beta(0) mutations.