Autoimmune Polyglandular Disease Research Articles

FRI644 A Rare Case Of Autoimmune Polyglandular Disease Type 3, With Scleredema Adultorum Of Buschke, Type 1 Diabetes And Graves Disease

Abstract Disclosure: C. Pérez-Castañeda: None. G.A. González-Villaseñor: None. M. Mercado: None. A. Pozos-Ochoa: None. H.J. Medina: None. E. Gamez: None. M.T. Muñoz-Magallanes: None. Background: Scleredema Adultorum of Buschke is an uncommon skin disease, characterized by hardening and stiffness of the subcutaneous tissues, which typically starts at the neck; affecting the upper back causing immobilization; it may develop both in type 1 and type 2 diabetes mellitus and it is related with prolonged exposure to hyperglycemia, obesity and poor metabolic control. Treatment options include topical as well as systemic treatments and physical modalities; but therapy is often reported as unsuccessful. We present a case of scleredema of Buschke occurring in a patient with Autoimmune Polyglandular Disease Type 3 involving thyroid autoimmune disease and type one diabetes which to our knowledge it´s the first time to be described in literature. Clinical Case: A 42 year old male presented with history of a long standing type 1 diabetes and hypothyroidism after radioiodine treatment for refractory Graves´ disease. He complained of skin thickening and hardening in the nape, back and shoulder areas which has been slowly progressing over the last six years. Physical examination revealed a symmetric, painless, poorly defined non-pitting induration of the skin, with hyperpigmentation and peau d´ orange appearance, involving the back of the scalp, neck, upper back and both shoulders; at palpation there was a woody 1 hardness and thickness of the skin associated with failure of either rolling nor pinching the skin. There was a significant decreased range of motion in both shoulders. We performed an ultrasound which demonstrated an increased thickness of the dermis with a pronounced posterior acoustic shadow and presence of multiple echogenic dots. A magnetic resonance was subsequently conducted, revealing a thickening of the skin at subcutaneous tissue primarily through the interscapular region and a hyperintense band at the dermis. Biopsy specimen showed collagen bundles separated by gaps that correspond to mucopolysaccharide deposits. The patient was followed at the outpatient clinic, we initiated physiotherapy and we adjusted his diabetes treatment in order to achieve adequate control, the patient now refers a steady state on the clinical picture. Conclusion: Scleredema is a rare disease, treatment options include topical as well as systemic treatments and physical modalities; but therapy is often reported as unsuccessful, probably associated with the few cases published in the literature; so there is no standard therapeutic protocol. The course is usually unpredictable and the disease itself is refractory. This is the first case reporting the rare association of type one diabetes, Grave s disease and scleredema of Buschke. 2 Presentation: Friday, June 16, 2023

REFERRAL FOR SUN ALLERGY – A CASE OF ERYTHROPOIETIC PROTOPORPHYRIA

<h3>Introduction</h3> Erythropoietic protoporphyria (EPP) is an inherited cutaneous porphyria characterized by painful, non-blistering photosensitivity usually noted in early childhood and occurring acutely after sunlight exposure. Cutaneous lesions develop within minutes of sun exposure with diffuse edema of the skin in sun-exposed areas, resembling angioedema. EPP is now recognized as the most common porphyria in children and the third most common in adults. In the review of over 100 cases in the United States, the average delay diagnosis of EPP was 13 years. <h3>Case Description</h3> A 29-year-old female with a PMH of polyglandular autoimmune disease presented to the Allergy clinic as a referral for "Sun Allergy". The patient reported a near lifelong history of a photosensitive rash. The rash typically begins 10-20 minutes after sun exposure, sparing covered areas. The rash is described as burning/stinging in nature, a 10/10 on the pain scale. She additionally reported intermittent, small bullae in affected areas. She denied pruritus and urticaria. Patient denied recent NSAID and antibiotic use. She denied the use of topicals, including sunscreen. Patient has one full sibling with a similar clinical course. Patient denied history of substance use disorder. Porphyria became the leading differential diagnosis. Serum porphyrins with reflex porphyrins were obtained and indicated elevated total serum porphyrins with notable reflex indicating elevated protoporphyrins. The patient was diagnosed with Erythropoietic Porphyria and referred to Dermatology for further management. <h3>Discussion</h3> This case highlights the importance of including porphyrias in the differential diagnosis of photosensitive rashes, which may be referred to Allergy and Immunology clinics for evaluation.

Polyglandular Autoimmune Syndrome Triggered after CTLA-4 and PD-1L Immunotherapy Treatment

Background: CTLA-4 and PD-1L are novel immune checkpoint targets for cancer treatment with specific side effects such as autoimmune diseases. Less frequently, the presence of several autoimmune diseases in the same patient has been described. In this communication, we illustrate the case of a 45-year-old patient with a previous diagnosis of advanced cancer that, after starting treatment with this immunotherapy, developed in the following months autoimmune diabetes, lymphocytic hypophysitis, and a Hashimoto thyroiditis in an abrupt and intense manner that would correspond to an autoimmune polyglandular disease. Discussion: The activation of autoimmunity and associated diseases is increasing in parallel with augmented indication of these immunotherapeutic treatments in cancer patients. A closer follow-up of these patients could be necessary for an optimal approach to this type of pathology. Conclusions: Different autoimmune diseases can converge in the same patient when immunotherapy for cancer is indicated to boost immune response against tumor, caused by altering immune tolerance.

Asymptomatic riedel thyroiditis presented in a patient with thyroid storm and polyglandular autoimmune disease

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

A case of polyglandular autoimmune disease associated with common variable immunodeficiency

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

IgG4 antibodies in autoimmune polyglandular disease and IgG4-related endocrinopathies: pathophysiology and clinical characteristics.

This review discusses the IgG4-related disease spectrum (IgG4-RD), the autoimmune polyglandular syndromes (APS), the association of IgG4 with APS, and possible pathobiology. IgG4-RD is a multiorgan autoimmune disorder characterized by fibrous inflammation, IgG4-positive plasma cell infiltration in affected tissues, and elevated serum concentrations of IgG4. IgG4-RD can affect any organ and has a heterogeneous presentation. Consensus criteria for diagnosis in specific organs have been established. The recognition and diagnosis of IgG4-RD are crucial because the disease responds favorably to immunosuppression (e.g., glucocorticoids, rituximab). The precise mechanisms leading to disease are unknown, but IgG4 antibodies may undergo a half antibody exchange, which renders them incapable of activating the complement pathway. Despite significant advances in disease recognition and treatment strategies, the disorder remains poorly understood. The precise role of IgG4, whether it is protective or pathogenic, is still being debated.

Hashimoto's Thyroiditis and Entero-Chromaffin-like Cell Hyperplasia: Early Detection and Somatostatin Analogue Treatment

Type IIIb polyglandular autoimmune disease comprises autoimmune thyroid disease (HT) and chronic atrophic gastritis (AIG). Hypergastrinemia, secondary to AIG, predisposes to gastric enterochromaffin-like cell (ECL) hyperplasia, a preneoplastic condition. We evaluated the prevalence of AIG, hypergastrinemia and ECL hyperplasia in HT patients. A secondary end-point was to assess the efficacy of treatment with a somatostatin analogue in HT patient with ECL hyperplasia. From 2009 to 2011, 146 HT patients were enrolled in a prospective study. All cases underwent hormonal profile, and parietal cell antibody (PCA), gastrin, and chromogranin A (CgA) serum level assays. Selected patients with elevated gastrin and CgA levels underwent gastro esophageal endoscopy (EGDS). Patients positive for ECL hyperplasia received Octreotide LAR 30 mg/28 days for 12 months. Gastrin and CgA assays were repeated every three months and EGDS after one year. The results show that gastrin and CgA were significantly higher than normal in 17/115 (14.7%) patients. Seven more HT had isolated PCA positivity and in the 17 PCA positive patients histology diagnosed AIG, corpus prevalent, with mild to moderate atrophy. Diffuse ECL hyperplasia of the gastric body was present in three subjects, one of them presenting a type-1 carcinoid. Gastrin and CgA levels were significantly reduced (p&lt;0.01) after 3 months of therapy with a somatostatin analogue and returned to normal after 1 year. ECL hyperplasia regressed in all three patients. We suggest that selected HT patients may need a more accurate surveillance for early signs of gastric EC risk. In the case of altered values of gastrin and in the presence of PCA positivity, EGDS and histology should be performed for an early diagnosis of AIG and treatment of ECL hyperplasia.

The Treatment of Pernicious Anemia in Children with Graves' Disease

Organ specific autoimmune diseases may occur in the same individual. Type III polyglandular autoimmune disease is defined by the occurrence in the same individual of two or more of the following: autoimmune thyroid disease, pernicious anemia, insulin dependent diabetes, and other organ specific autoimmune diseases not falling into class I or class II categories. A 16-year-old girl developed pernicious anemia during the treatment of Graves' disease. She was diagnosed with Graves' disease 5 years ago and had received methimazole 20 mg/day, but the medication was not well tolerated. Bone marrow findings were compatible with pernicious anemia as macrocytic normochromic red blood cell (RBC) and increased megakaryocyte. The serum value of vitamin B12 was low, and the serum titer of antibody to gastric parietal cell was high. After diagnosis of pernicious anemia, she had treatment by monthly intramuscular vitamin B12 and methimazole (20 mg/day). The values of hemoglobin and RBC indices as well as thyroid function were normalized after 2 months. Vitamin B12 therapy was maintained for 1 year with normal RBC indices. At present, she dose not receive treatment with vitamin B12 but she does receive methimazole treatment. We report a case of treatment of pernicious anemia in a 16 year-old girl during treatment for Graves disease.

Concurrent Autoimmune Diseases in Patients With Autoimmune Hepatitis

Although the pathomechanisms of autoimmune diseases in various organs remain unresolved, an accumulation of autoimmune diseases in individual patients has been observed. An overlap of autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC) or primary sclerosing cirrhosis has been well documented. However, the overlap of autoimmune diseases other than PBC or PSC has not yet been investigated in a large cohort. The goal of our analysis was to investigate the incidence of concurrent autoimmune diseases in patients with AIH. We analyzed our cohort of 278 patients with AIH for concurrent autoimmune diseases. A total of 111 patients (40%) were diagnosed with additional autoimmune diseases. Besides overlap syndromes for PBC and PSC, autoimmune thyroiditis was the most common concurrent disease (28 patients, 10%). Other concurrent autoimmune diseases comprised vitiligo (5 patients), rheumatoid arthritis (5 patients), Sjogren syndrome (4 patients), ulcerative colitis (4 patients), conjunctivitis (4 patients), celiac disease (3 patients), systemic lupus erythematodes (2 patients), type I diabetes (2 patients), multiple sclerosis (2 patients), polymyalgia rheumatica (2 patients), and urticaria (2 patients). One patient each was diagnosed with Crohn's disease, autoimmune gastritis, collagenous colitis, hypophysitis, and sarcoidosis. Investigating 100 patients with polyglandular syndrome and autoimmune thyroid disease for the occurrence of autoantibodies associated with AIH, we identified AIH-associated antibodies only in 1 patient. Concurrent autoimmune diseases are common in patients with AIH and mirror the full range of known autoimmune diseases. Therefore, an extended diagnostic screening for accumulating autoimmune diseases, especially autoimmune thyroiditis, seems reasonable in patients with AIH.

Aire

Mutations in the transcriptional regulator, Aire, cause APECED, a polyglandular autoimmune disease with monogenic transmission. Animal models of APECED have revealed that Aire plays an important role in T cell tolerance induction in the thymus, mainly by promoting ectopic expression of a large repertoire of transcripts encoding proteins normally restricted to differentiated organs residing in the periphery. The absence of Aire results in impaired clonal deletion of self-reactive thymocytes, which escape into the periphery and attack a variety of organs. In addition, Aire is a proapoptotic factor, expressed at the final maturation stage of thymic medullary epithelial cells, a function that may promote cross-presentation of the antigens encoded by Aire-induced transcripts in these cells. Transcriptional regulation by Aire is unusual in being very broad, context-dependent, probabilistic, and noisy. Structure/function analyses and identification of its interaction partners suggest that Aire may impact transcription at several levels, including nucleosome displacement during elongation and transcript splicing or other aspects of maturation.

Autoimmune gastritis and parietal cell reactivity in two children with abnormal intestinal permeability

Autoimmune gastritis is characterised by lymphocytic infiltration of the gastric submucosa, with loss of parietal and chief cells and achlorhydria. Often, gastritis is expressed clinically as cobalamin deficiency with megaloblastic anaemia, which is generally described as a disease of the elderly. Here, we report on two prepubertal children who developed autoimmune gastritis. One child developed autoimmune gastritis as part of a polyglandular autoimmune disease from a family with polyglandular autoimmune disease type II (PGA type II) and the other as part of a classic "thyro-gastric cluster," which may have been triggered by emotional trauma. Both children presented with normal small bowel biopsies, with abnormal gut permeability, which subsequently resolved. These patients are among the youngest reported to date. The immune systems targetted the gastric parietal cell autoantigens (ATP4A and ATP4B) in both children, similar to the elderly. The study of children with autoimmune gastritis and their families may provide additional insights into the disease's pathogenesis and may also lead to the identification of inheritable factors influencing susceptibility. This report underlines the necessity to screen paediatric patients with organ-specific autoimmune diseases for co-existent conditions. Children with polyglandular autoimmune disease are at particularly high risk.

Gènes de l’ovaire

The number of ovarian follicles decreases during genital life by apoptosis, which accelerates from 40 until the menopause. Several findings plead in favour of a genetic control of these events. Ovarian insufficiency can occur by three mechanisms: reduction in the primary follicles reserve (ataxia-telangiectasy), follicular maturation blocking (modification of the genes GDF-9 and GDF-9B, null mutation of FSH receptor gene, auto-immune polyglandular disease, PBE syndrome), or apoptosis acceleration (chemotherapy, smoking, galactosemia, Turner’s syndrome). However, the aetiology of premature ovarian insufficiencies in woman remains unknown in more than 90% of the cases. Genetic studies on the family cases should make it possible to identify new genes involved in ovarian control.

Personality traits' trending to influence outcome in bipolar disorder

Exon trapping was performed from a partial cosmid, PAC, and P1 clone contig from human chromosome 21 betweenMX1and 21qter to identify genes that may be involved in the pathogenesis of Down syndrome or several of the genetic diseases that map to chromosome 21q22.3. One 19-bp exon showed identity to three ESTs. The complete sequence of the EST clones, RT-PCR, and cDNA library screening were used to determine the full-length cDNA sequence of 2.2 kb with an open reading frame of 256-amino-acids. The putative 256-amino-acid peptide has homology with a hypotheticalCaehorhabditis elegansprotein of unknown function. Northern blot analysis of this gene, termed C21orf2 (chromosome 21 open reading frame 2), revealed two ubiquitously expressed mRNAs of 2.2 and 1.2 kb produced by use of alternative polyadenylation sites. Hybridization of the EST clones to a cosmid contig in chromosome 21q22.3 mapped C21orf2 just distal toPFKL,a critical mapping region for several genetic diseases. Comparison to publicly available genomic sequence, and additional data, revealed that the gene is split into seven exons over 10.5 kb, further refining the mapping position to only 1.2 kb distal toPFKLwith the direction of transcription toward the centromere. The 5′UTR is contiguous withD21S400,and intron 2 contains a 52-bp VNTR polymorphism. Given its mapping position, C21orf2 is a candidate for involvement in disorders including autoimmune polyglandular disease type I (also called autoimmune polyendocrinopathy candidiasis ectodermal dystrophy or APECED) and the autosomal nonsyndromic deafness loci, DFNB8 and DFNB10. Mutation analysis using sequencing of RT-PCR and genomic DNA-derived PCR products, SSCP, and Southern and Northern blot analyses in APECED patients excluded C21orf2 as the gene for APECED.

Assessing the feasibility of an allelic association between bipolar affective disorder and region 21q22.3

Exon trapping was performed from a partial cosmid, PAC, and P1 clone contig from human chromosome 21 betweenMX1and 21qter to identify genes that may be involved in the pathogenesis of Down syndrome or several of the genetic diseases that map to chromosome 21q22.3. One 19-bp exon showed identity to three ESTs. The complete sequence of the EST clones, RT-PCR, and cDNA library screening were used to determine the full-length cDNA sequence of 2.2 kb with an open reading frame of 256-amino-acids. The putative 256-amino-acid peptide has homology with a hypotheticalCaehorhabditis elegansprotein of unknown function. Northern blot analysis of this gene, termed C21orf2 (chromosome 21 open reading frame 2), revealed two ubiquitously expressed mRNAs of 2.2 and 1.2 kb produced by use of alternative polyadenylation sites. Hybridization of the EST clones to a cosmid contig in chromosome 21q22.3 mapped C21orf2 just distal toPFKL,a critical mapping region for several genetic diseases. Comparison to publicly available genomic sequence, and additional data, revealed that the gene is split into seven exons over 10.5 kb, further refining the mapping position to only 1.2 kb distal toPFKLwith the direction of transcription toward the centromere. The 5′UTR is contiguous withD21S400,and intron 2 contains a 52-bp VNTR polymorphism. Given its mapping position, C21orf2 is a candidate for involvement in disorders including autoimmune polyglandular disease type I (also called autoimmune polyendocrinopathy candidiasis ectodermal dystrophy or APECED) and the autosomal nonsyndromic deafness loci, DFNB8 and DFNB10. Mutation analysis using sequencing of RT-PCR and genomic DNA-derived PCR products, SSCP, and Southern and Northern blot analyses in APECED patients excluded C21orf2 as the gene for APECED.

The Young Low Responder and Polyglandular Autoimmunity

Objectives: Recruitment and stimulation of a healthy cohort of oocytes remains the single most significant factor in the success of non-donor assisted reproduction (ART). Although an age-dependent decrease in ovarian reserve and fecundity is physiologic in women >40, the younger asymptotic low responder (LR) presents significant endocrine and ethical dilemmas concerning stimulation protocols and the ultimate decision to pursue donor oocytes.Design: Prospective evaluation of women demonstrating a low response to controlled ovarian hyperstimulation.Materials and Methods: 50 healthy, euthyroid, eumenorrheic women without endometriosis, previous surgery or significant family history, who were stimulated by ≥3 ampules of menotropins (HMG) produced ≤3 follicles. A control group of 18 similar euthyroid, eumenorrheic women with secondary infertility and normal HMG response served as the control group. 10 women with known premature ovarian failure were also included. All underwent evaluation of basal follicle stimulation hormone (FSH), thyroid stimulating hormone (TSH), thyroid antibody, antinuclear antibody (ANA) and sonographic assessment of mean pre-HMG ovarian diameter. ∗Results:AgeBasal FSHMean ovarian diameterHMG follicles+Thyroid antibodyControl33.75.830.17.427%LR<3934.68.3∗Significant differences P<0.05 control.24.1∗Significant differences P<0.05 control.2.2∗Significant differences P<0.05 control.68%∗Significant differences P<0.05 control.LR>3943.111.2∗Significant differences P<0.05 control.20.8∗Significant differences P<0.05 control.1.8∗Significant differences P<0.05 control.22%POF35.198.4∗Significant differences P<0.05 control.18.7∗Significant differences P<0.05 control.—44%∗ Significant differences P<0.05 control. Open table in a new tab Conclusions: The results of this study suggest: 1) The vast majority of unsuspected eumenorrheic LR demonstrates significantly decreased ovarian mass, similar to premature ovarian failure. 2) LR>39 years are most likely physiologic LR due to variabilities in decremental ovarian reserve. 3) LR<39 years demonstrates decreased ovarian mass, and a significant incidence of asymptomatic thyroid auto-antibody consistent with incipient polyglandular autoimmune disease. 4) The finding of ovarian diameters <25 mm and thyroid antibodies in young, eumenorrheic women suggests a poor prognosis for any fertility therapy and early counseling for donor oocytes as well as surveillance for autoimmune polyglandular sequelae. Objectives: Recruitment and stimulation of a healthy cohort of oocytes remains the single most significant factor in the success of non-donor assisted reproduction (ART). Although an age-dependent decrease in ovarian reserve and fecundity is physiologic in women >40, the younger asymptotic low responder (LR) presents significant endocrine and ethical dilemmas concerning stimulation protocols and the ultimate decision to pursue donor oocytes. Design: Prospective evaluation of women demonstrating a low response to controlled ovarian hyperstimulation. Materials and Methods: 50 healthy, euthyroid, eumenorrheic women without endometriosis, previous surgery or significant family history, who were stimulated by ≥3 ampules of menotropins (HMG) produced ≤3 follicles. A control group of 18 similar euthyroid, eumenorrheic women with secondary infertility and normal HMG response served as the control group. 10 women with known premature ovarian failure were also included. All underwent evaluation of basal follicle stimulation hormone (FSH), thyroid stimulating hormone (TSH), thyroid antibody, antinuclear antibody (ANA) and sonographic assessment of mean pre-HMG ovarian diameter. ∗Results:AgeBasal FSHMean ovarian diameterHMG follicles+Thyroid antibodyControl33.75.830.17.427%LR<3934.68.3∗Significant differences P<0.05 control.24.1∗Significant differences P<0.05 control.2.2∗Significant differences P<0.05 control.68%∗Significant differences P<0.05 control.LR>3943.111.2∗Significant differences P<0.05 control.20.8∗Significant differences P<0.05 control.1.8∗Significant differences P<0.05 control.22%POF35.198.4∗Significant differences P<0.05 control.18.7∗Significant differences P<0.05 control.—44%∗ Significant differences P<0.05 control. Open table in a new tab Conclusions: The results of this study suggest: 1) The vast majority of unsuspected eumenorrheic LR demonstrates significantly decreased ovarian mass, similar to premature ovarian failure. 2) LR>39 years are most likely physiologic LR due to variabilities in decremental ovarian reserve. 3) LR<39 years demonstrates decreased ovarian mass, and a significant incidence of asymptomatic thyroid auto-antibody consistent with incipient polyglandular autoimmune disease. 4) The finding of ovarian diameters <25 mm and thyroid antibodies in young, eumenorrheic women suggests a poor prognosis for any fertility therapy and early counseling for donor oocytes as well as surveillance for autoimmune polyglandular sequelae.

Is disomic homozygosity at the APECED locus the cause of increased autoimmunity in Down’s syndrome?

AIMSTo examine the age of onset of insulin dependent diabetes mellitus (IDDM) in children with Down’s syndrome compared with non-trisomic individuals, and to assess whether differences might be related to...

Construction of a 2.5-Mb Integrated Physical and Gene Map of Distal 21q22.3

The gene-rich telomeric region of 21q harbors several loci relevant to human diseases including autoimmune polyglandular disease type I, nonsyndromic deafness, Knobloch syndrome, holoprosencephaly, and bipolar affective disorder. A contig of genomic clones in this region would facilitate the isolation of these genes. However, distal 21q22.3 has yet been poorly mapped, presumably due to the presence of sequences that are underrepresented in yeast artificial chromosome (YAC) libraries. We generated a framework of YACs and used these clones as starting points for the isolation of a combination of bacterial artificial chromosome clones, P1-derived artificial chromosome clones, and cosmid clones by chromosome walking procedures. These studies resulted in the construction of a high-resolution contig map spanning the 2.5-Mb region from PFKL to the telomere, ∼2 Mb of which are covered by ready-to-sequence contigs. Within this map we determined the location and relative distance of 21 markers. These include 9 established genetic markers, the order of which is cen–PFKL–D21S154–D21S170– D21S171–D21S1903–D21S1897–D21S112–D21S1446–D21S1575–tel. Moreover, we established the precise map position of 13 genes and 4 ESTs including the recently isolated genes C21ORF2, SMT3H1, RNA editing deaminase 1 (ADARB1), folate transporter (SLC19A1), COL18A1, lanosterol synthase (LSS-PEN), pericentrin (PCNT), and arginine methyltransferase (HRMT1L1). This integrated map provides a useful resource for the mapping and isolation of disease genes and for the construction of a complete transcription map of distal 21q as well as for large-scale sequencing efforts.

Characterization of a Novel Gene, C21orf2, on Human Chromosome 21q22.3 and Its Exclusion as the APECED Gene by Mutation Analysis

Exon trapping was performed from a partial cosmid, PAC, and P1 clone contig from human chromosome 21 betweenMX1and 21qter to identify genes that may be involved in the pathogenesis of Down syndrome or several of the genetic diseases that map to chromosome 21q22.3. One 19-bp exon showed identity to three ESTs. The complete sequence of the EST clones, RT-PCR, and cDNA library screening were used to determine the full-length cDNA sequence of 2.2 kb with an open reading frame of 256-amino-acids. The putative 256-amino-acid peptide has homology with a hypotheticalCaehorhabditis elegansprotein of unknown function. Northern blot analysis of this gene, termed C21orf2 (chromosome 21 open reading frame 2), revealed two ubiquitously expressed mRNAs of 2.2 and 1.2 kb produced by use of alternative polyadenylation sites. Hybridization of the EST clones to a cosmid contig in chromosome 21q22.3 mapped C21orf2 just distal toPFKL,a critical mapping region for several genetic diseases. Comparison to publicly available genomic sequence, and additional data, revealed that the gene is split into seven exons over 10.5 kb, further refining the mapping position to only 1.2 kb distal toPFKLwith the direction of transcription toward the centromere. The 5′UTR is contiguous withD21S400,and intron 2 contains a 52-bp VNTR polymorphism. Given its mapping position, C21orf2 is a candidate for involvement in disorders including autoimmune polyglandular disease type I (also called autoimmune polyendocrinopathy candidiasis ectodermal dystrophy or APECED) and the autosomal nonsyndromic deafness loci, DFNB8 and DFNB10. Mutation analysis using sequencing of RT-PCR and genomic DNA-derived PCR products, SSCP, and Southern and Northern blot analyses in APECED patients excluded C21orf2 as the gene for APECED.

Human Pyridoxal Kinase: cDNA CLONING, EXPRESSION, AND MODULATION BY LIGANDS OF THE BENZODIAZEPINE RECEPTOR

Peptide fragments of a porcine benzodiazepine-binding protein were used to isolate the cDNA of a related human protein. The cDNA encodes a polypeptide of 312 amino acid residues that is homologous to a bacterial pyridoxal kinase. Transient expression of the cDNA in human embryonic kidney cells confirmed that it encodes human pyridoxal kinase. The recombinant enzyme displayed a Km value of 3.3 microM for pyridoxal and was inhibited competitively by 4-deoxypyridoxine (Ki = 2.8 microM). Benzodiazepine receptor ligands that bound to the purified porcine protein also exerted a potent inhibitory effect on human pyridoxal kinase activity. Transcripts of the pyridoxal kinase gene were detectable in all human tissues examined, and were particularly abundant in the testes. The gene is localized on chromosome 21q22.3 and represents a candidate gene for at least one genetic disorder that has been mapped to this region (autoimmune polyglandular disease type 1).

Localization of 16 exons to a 450-kb region involved in the autoimmune polyglandular disease type I (APECED) on human chromosome 21q22.3.

As a step toward identifying the pathogenic genes for autoimmune polyglandular disease type I (APECED) and other disorders mapped to the PFKL locus on chromosome 21q22.3, we have constructed a cosmid/BAC (bacterial artificial chromosome) contig of 450 kb covering markers D21S1460-D21S25-PFKL-D21S154 and performed exon trapping. We isolated 22 distinct exons including 6 exons derived from two known genes (PFKL and EHOC-1). Among 16 novel exons, 2 exons matched with human expressed sequence tags (EST) and 7 exons showed homology at predicted amino acid sequence level with proteins from other species. These 16 exons were mapped back to the cosmid contigs, 12 of which were confirmed for their expression by polymerase chain reaction (PCR) screening of human cDNA libraries of various tissues. These exon sequences and a transcript map will aid for isolation of corresponding genes which will be identified as candidate genes involved in the pathogenesis of disorders mapped to the 21q22.3 region.