TINF2, a component of the shelterin telomere protection complex, is mutated in dyskeratosis congenita

Patients with dyskeratosis congenita (DC), a heterogeneous inherited bone marrow failure syndrome, have abnormalities in telomere biology, including very short telomeres and germline mutations in DKC1, TERC, TERT, or NOP10, but approximately 60% of DC patients lack an identifiable mutation. With the very short telomere phenotype and a highly penetrant, rare disease model, a linkage scan was performed on a family with autosomal-dominant DC and no mutations in DKCI, TERC, or TERT. Evidence favoring linkage was found at 2p24 and 14q11.2, and this led to the identification of TINF2 (14q11.2) mutations, K280E, in the proband and her five affected relatives and TINF2 R282H in three additional unrelated DC probands, including one with Revesz syndrome; a fifth DC proband had a R282S mutation. TINF2 mutations were not present in unaffected relatives, DC probands with mutations in DKC1, TERC, or TERT or 298 control subjects. We demonstrate that a fifth gene, TINF2, is mutated in classical DC and, for the first time, in Revesz syndrome. This represents the first shelterin complex mutation linked to human disease and confirms the role of very short telomeres as a diagnostic test for DC.

Recurrence characteristics in European patients with ocular toxoplasmosis

BACKGROUND: The risk of function loss after each episode of ocular toxoplasmosis (OT) supports efforts to improve our understanding of the disease. Patients and methods: 139 patients with OT were contacted retrospectively and requested to complete a questionnaire addressing course and activity of their disease. This information was compared with that retrieved from their medical records. Sixty-three patients completed the questionnaire and were included in the study. They were allocated according to their median age to one of two groups (group 1: <20.9 years; group 2: >or=20.9 years). RESULTS: The mean reported age at the time of first ocular manifestation was 23.9 (median 20.9, range 0 to 70.5; SD 12.9) years. The clinical diagnosis was made 3.5 years later (p = 0.0008). The follow-up time was 6.5 (median 5.0; range 0.5 to 49.9; SD 7.6) years. The recurrence rate was higher in patients below 20.9 years (66%; n = 35) than in older patients (39%; n = 28; chi(2) test, p<0.05). Patients reporting only one episode were older at first manifestation (29.6 (median 25.6; range 10.6 to 70.5; SD 14.3) years; n = 29) than those reporting two episodes (17.9 (median 19.5; range 5.9 to 33.9; SD 7.8) years; n = 15 (p<0.05)). The proportion of patients who developed a recurrence was 54-63% after each episode without a tendency to enlarge, and the interval between successive episodes remained stable between 1.0 and 1.7 years for the first three recurrences. CONCLUSION: Younger OT patients carry a higher risk of developing a recurrence than older ones. After each episode, two-thirds of all OT patients will develop another one.

Exon 17 skipping in CLCN1 leads to recessive myotonia congenita

Mutations in CLCN1, the gene encoding the ClC-1 chloride channel in skeletal muscle, lead to myotonia congenita. The effects on the intramembranous channel forming domains have been investigated more than that at the intracellular C-terminus. We have performed a mutation screen involving the whole CLCN1 gene of patients with myotonia congenita by polymerase chain reaction (PCR), single-strand conformation polymorphism studies, and sequencing. Two unrelated patients harbored the same homozygous G-to-T mutation on the donor splice site of intron 17. This led to the skipping of exon 17, as evidenced by the reverse transcriptase PCR. When the exon 17-deleted CLCN1 was expressed in Xenopus oocytes, no chloride current was measurable. This function could be restored by coexpression with the wild-type channel. Our data suggest an important role of this C-terminal region and that exon 17 skipping resulting from a homozygous point mutation in CLCN1 can lead to recessive myotonia congenita.

Toxoplasma gondii Infection in Kyrgyzstan: Seroprevalence, Risk Factor Analysis, and Estimate of Congenital and AIDS-Related Toxoplasmosis

Background HIV-prevalence, as well as incidence of zoonotic parasitic diseases like cystic echinococcosis, has increased in the Kyrgyz Republic due to fundamental socio-economic changes after the breakdown of the Soviet Union. The possible impact on morbidity and mortality caused by Toxoplasma gondii infection in congenital toxoplasmosis or as an opportunistic infection in the emerging AIDS pandemic has not been reported from Kyrgyzstan. Methodology/Principal Findings We screened 1,061 rural and 899 urban people to determine the seroprevalence of T. gondii infection in 2 representative but epidemiologically distinct populations in Kyrgyzstan. The rural population was from a typical agricultural district where sheep husbandry is a major occupation. The urban population was selected in collaboration with several diagnostic laboratories in Bishkek, the largest city in Kyrgyzstan. We designed a questionnaire that was used on all rural subjects so a risk-factor analysis could be undertaken. The samples from the urban population were anonymous and only data with regard to age and gender was available. Estimates of putative cases of congenital and AIDS-related toxoplasmosis in the whole country were made from the results of the serology. Specific antibodies (IgG) against Triton X-100 extracted antigens of T. gondii tachyzoites from in vitro cultures were determined by ELISA. Overall seroprevalence of infection with T. gondii in people living in rural vs. urban areas was 6.2% (95%CI: 4.8–7.8) (adjusted seroprevalence based on census figures 5.1%, 95% CI 3.9–6.5), and 19.0% (95%CI: 16.5–21.7) (adjusted 16.4%, 95% CI 14.1–19.3), respectively, without significant gender-specific differences. The seroprevalence increased with age. Independently low social status increased the risk of Toxoplasma seropositivity while increasing numbers of sheep owned decreased the risk of seropositivity. Water supply, consumption of unpasteurized milk products or undercooked meat, as well as cat ownership, had no significant influence on the risk for seropositivity. Conclusions We present a first seroprevalence analysis for human T. gondii infection in the Kyrgyz Republic. Based on these data we estimate that 173 (95% CI 136–216) Kyrgyz children will be born annually to mothers who seroconverted to toxoplasmosis during pregnancy. In addition, between 350 and 1,000 HIV-infected persons are currently estimated to be seropositive for toxoplasmosis. Taken together, this suggests a substantial impact of congenital and AIDS-related symptomatic toxoplasmosis on morbidity and mortality in Kyrgyzstan.

Chloride channels in myotonia congenita assessed by velocity recovery cycles

Introduction: Myotonia congenita (MC) is caused by congenital defects in the muscle chloride channel CLC-1. This study used muscle velocity recovery cycles (MVRCs) to investigate how membrane function is affected. Methods: MVRCs and responses to repetitive stimulation were compared between 18 patients with genetically confirmed MC (13 recessive, 7 dominant) and 30 age-matched normal controls. Results: MC patients exhibited increased early supernormality, but treatment with sodium channel blockers prevented this. After multiple conditioning stimuli, late supernormality was enhanced in all MC patients, indicating delayed repolarization. These abnormalities were similar between the MC subtypes, but recessive patients showed a greater drop in amplitude during repetitive stimulation. Discussion: MVRCs indicate that chloride conductance only becomes important when muscle fibers are depolarized. The differential responses to repetitive stimulation suggest that in dominant MC the affected chloride channels are activated by strong depolarization, consistent with a positive shift of the CLC-1 activation curve. © 2013 Wiley Periodicals, Inc.

Natural history study of arthrogryposis multiplex congenita, amyoplasia type

Arthrogryposis or Arthrogrypsosis Multiplex Congenita (AMC) are terms used to describe the clinical finding of multiple congenital contractures. There are more than 300 distinct disorders associated with arthrogryposis. Amyoplasia is the most common type of arthrogryposis and is often referred to as the “classic” type. There is no known cause of amyoplasia and no risk factors have been identified. Moreover, there is no established diagnostic criteria, which has led to inconsistency and confusion in the medical literature. The purpose of this study was to describe the natural history of amyoplasia, to determine if there are any identifiable risk factors and develop a list of diagnostic criteria. A retrospective chart review of 59 children with arthrogryposis ascertained at the Shriners Hospitals for Children in Houston, Texas was performed and included the following information: prenatal, birth, and family histories, and phenotypic descriptions. Forty-four children were identified with amyoplasia and 15 children with other multiple congenital contractures and other anomalies (MCC) were used as a comparison group. With the exception of abnormal amniotic fluid levels during pregnancy, there were no significant demographic or prenatal risk factors identified. However, we found common features that discriminate amyoplasia from other types of arthrogryposis and developed a diagnostic checklist. This checklist can be used as diagnostic criteria for discriminating amyoplasia from isolated and multiple contracture conditions.

Seroprevalence of toxoplasmosis and current thinking regarding screening in pregnancy: A review of the literature and case study discussion

The approach to the diagnosis and treatment of congenital toxoplasmosis has been one of flux and debate, fueled by lack of knowledge, lack of consensus, different methods of screening and different national policies for screening in different parts of the world. Countries with higher prevalence of disease such as in Europe and South America have a heightened awareness of the need to screen and treat for this parasitic infection during pregnancy. In contrast, in the United States, it is a condition scarcely discussed and has been largely ignored except in some large centers and by a few researchers. Policies and research strategies for any condition should start with obtaining good data. The aims of this thesis included a review of prevalence studies conducted in the United States, focused on the past 20 years, combined with a description of original research conducted by the author several years ago. The latter was a cross-sectional study performed in Houston, one of the largest American cities with a great ethnic mix. The study analyzed prevalence rates of Toxoplasma gondii IgG antibody in sera of women of reproductive age. Overall seroprevalence was 12.3%. In keeping with other studies, higher prevalence correlated with lower socioeconomic status, Black and Hispanic and Asian ethnicities, and increasing age. A literature search revealed only three prevalence studies performed in the United States over the past 20 years, with another four studies only referred to as personal communications or within a textbook, without further study detail available. The literature review also revealed a lack of consensus on whether or not to screen for toxoplasmosis in pregnancy, and even whether or not treatment in utero is worthwhile.^ Proponents of screening and treatment in pregnancy site studies both in the United States and France, emphasize that treatment reduces disease manifestations in infants. Opponents cite other studies that show only marginal benefits, together with potential side effects of medication regimens and generation of anxiety in parents. What is agreed on so far is the value of educating pregnant women on how to avoid contracting toxoplasmosis, and educating physicians on making the best use of reference laboratories before major treatment decisions are made. Further research to reevaluate the literature critically, review new treatment regimens and examine costs and benefits of screening and treatment of toxoplasmosis in pregnancy, bringing together European and American researchers, is needed.^

Toxoplasmosis; a bibliography of literature, 1956-September 1960 /

Mode of access: Internet.

Serodiagnosis of toxoplasmosis, rubella, cytomegalic inclusion disease, herpes simplex /

Includes bibliographies.

Toxoplasmosis of animals /

Includes bibliographical references (p. 414-472).

Aplicación y análisis del cuestionario cap (conocimientos, actitudes y prácticas) sobre toxoplasmosis para optómetras

Tesis (Optometra). -- Universidad de La Salle, Facultad de Ciencias de La Salud. Programa de Optometria, 2014