L’hypothyroïdie congénitale (HC), qui se traduit par une insuffisance d’hormone thyroïdienne (HT) à la naissance, est la maladie endocrinienne congénitale la plus fréquente avec une prévalence d’un cas sur 2,500 naissances vivantes. Non-traitée, cette insuffisance peut entrainer un retard de développement sévère, surtout au niveau cognitif. L’HC est le plus souvent due à un défaut lors du développement de la thyroïde (dysgénésie thyroïdienne (DT)) ou lors de la production des hormones thyroïdiennes (dyshormonogenèse (D)). La majorité des cas d’HC par dysgénésie thyroïdienne (HCDT) ont une ectopie, soit une glande mal positionnée. Contrairement aux dyshormonogenèses, qui s’expliquent fréquemment par des mutations dans les gènes responsables de la production des HT, selon un modèle autosomique récessif, les causes de l’HCDT demeurent largement inconnues. Certains arguments sont en faveur d’une prédisposition génétique (le risque relatif chez les parents de premier degré est de 40 fois supérieur à celui de la population générale) mais l’HCDT ne suit pas un modèle Mendélien: 98 % des cas sont sporadiques et 92 % des jumeaux monozygotiques sont discordants pour l’HCDT. De ce fait, nous avons suggéré une hypothèse de double-hit pour expliquer les HCDT, hypothèse combinant une prédisposition germinale (héritée ou de novo) à un évènement somatique (génétique ou épigénétique). Par le passé, nous avons étudié l’évènement somatique, mais nous n’avions pas encore étudié la prédisposition germinale. Le séquençage d’exome complet peut permettre d’identifier la cause génétique dans des formes familiales d’HC, mais aussi déterminer si les cas avec une HCDT isolée sont enrichis en variants délétères, tel qu’observé chez des patients avec une malformation cardiaque congénitale, patients qui partagent des caractéristiques similaires avec ceux atteints d’HCDT. De plus, cette technique pourrait permettre d’identifier de nouveaux gènes de prédisposition associés à l’HCDT. D’une part, nous avons séquencé l’exome d’un trio (parent-enfant) afin d’identifier la cause de l’HC dans une famille avec plusieurs enfants sévèrement atteints d’HC. D’autre part, nous avons comparé les données d’exome d’une cohorte de cas avec une HCDT isolée (HCDT non syndromique, HCDT-NS) à celles d’une cohorte contrôle, à l’aide d’une approche biaisée (gene-based burden) et non biaisée (gènes candidats). Finalement, nous avons développé le modèle de poisson-zèbre afin de pouvoir valider, in vivo, l’implication de potentiels gènes candidats, dans le développement thyroïdien. L’analyse de l’exome du trio a révélé un variant dans le gène TSHR qui co-ségrégait parfaitement avec le phénotype, et les études de minigène ont permis de montrer que ce variant intronique loin des sites d’épissage traditionnels introduisait un pseudo-exon dans la séquence du TSHR, créant ainsi un récepteur tronqué et inactif. L’analyse par comparaison de cohorte (cas-contrôle) a montré que les cas avec une HCDT-NS n’ont pas davantage de variants rares délétères comparé aux contrôles. De plus, après correction, le gene-based burden n’a pas identifié de gène candidat. Par contre, des variants rares pathogéniques ou probablement pathogéniques dans des gènes liés à l’hypothyroïdie congénitale ont été identifiés chez 42% des cas. Les études réalisées chez le poisson-zèbre sur un gène candidat, IKBKE, identifié par une analyse préliminaire de l’exome dans la cohorte de cas, confirme que les vaisseaux sanguins sont importants pour le bon positionnement de la glande thyroïde chez le poisson-zèbre, mais ne permet pas d’établir le rôle d’IKBKE dans la migration thyroïdienne. Nous avons d’abord montré que l’exome est une bonne technique pour identifier la cause de l’HC dans une famille avec plusieurs enfants atteints. Toutefois, une connaissance approfondie de la maladie et des isoformes du gène d’intérêt s’est avérée essentielle afin de bien analyser les données d’exome. Ensuite, nos résultats suggèrent que les cas avec une HCDT-NS n’ont pas davantage de variants délétères que les contrôles et que l’exome complet n’est pas suffisant pour identifier des gènes de prédisposition. Le séquençage du génome est peut-être nécessaire pour trouver une prédisposition génétique à l’HCDT-NS. Par contre, il est aussi possible que la génétique ne joue pas un rôle majeur dans les dysgénésies thyroïdiennes. Finalement, nous avons validé que le poisson-zèbre est un bon modèle pour étudier le développement de la thyroïde. / Congenital hypothyroidism (CH) is a disorder with a prevalence of one in 2,500 live births. CH can lead to severe intellectual disability if left untreated. It is most commonly caused by a defect during thyroid development (thyroid dysgenesis), which results in an ectopic gland in the majority of cases. A defect in thyroid hormone production (dyshormonogenesis) is the second most common cause of CH. In contrast to dyshormonogenesis, which generally has an identified cause and follows a Mendelian mode of inheritance, the cause of CHTD remains mostly unknown. CHTD is generally sporadic (98%) and has a high discordance rate (92%) between monozygotic twins. However, first-degree relatives are affected more often than by chance alone (40x) and there is an ethnic and female predominance. We thus hypothesized that CHTD is a disorder caused by two events, one germinal (a necessary but not sufficient predisposing factor) becoming pathogenic only if a second genetic or epigenetic event occurs at the somatic level. Whole exome sequencing (WES) can allow for identification of the genetic cause of CHTD in familial forms, but may also reveal if non-syndromic CHTD (NS-CHTD) cases are enriched in rare protein-altering variant, as seen in congenital heart malformations, a developmental defect that shares several characteristics with CHTD. Moreover, it might also identify new predisposing genes. First, we performed WES on a trio (parent-child) in a family with several siblings affected with severe CH. Second, we compared WES data of a NS-CHTD cohort with data from a control cohort, using a gene-based burden (unbiased) approach and a candidate gene (biased) approach to evaluate whether WES analysis allows to identify new predisposing genes in a well-characterized cohort. Finally, we developed the zebrafish model to test the roles of candidate genes, that will be identified by WES, in thyroid development. We first identified a variant in TSHR that segregated perfectly with the phenotype in the family with CHTD and a mini gene assay showed that this deep intronic variant induced a pseudo-exon, leading to a truncated protein missing the transmembrane domain, thus an inactive TSH receptor. Next, we found that NS-CHTD cases are not enriched in rare protein-altering variants and gene-base burden analysis did not identify novel candidate genes. However, WES data revealed pathogenic or likely pathogenic variants in CH-related genes in 42% of the NS-CHTD cases. Finally, zebrafish is a good model to study thyroid development and our results on IKBKE confirm the importance of vessels in thyroid positioning, but not its role in thyroid migration. First, we showed that WES analysis is a good tool to identify the causative variant in a family with several siblings affected by CH. However, the interpretation of the exome analysis required knowledge of the expression of the relevant isoforms and of the biology of the disease. Second, while a gene-based burden test, using WES data from a well-characterised NS-CHTD cohort, did not identified new predisposing genes, it identified pathogenic or likely pathogenic variants in 42% of the NS-CHTD cases. Whole genome sequencing might be required to identify the genetic causes in NS-CHTD. However, our result may indicate that genetics does not play a major role in thyroid dysgenesis. Finally, we have established that zebrafish is a good model to study thyroid development and may help, in the future, identify pathways implicated in this process.

This study is about evaluating the effectiveness of training in syndromic management ofSTDs. The purpose of this study was to fmd out to what extent the STD training programme had been implemented. A stratified sample of twenty-two primary health care clinics in the Port Shepstone region was used. Twenty-two professional nurses rendering STD management in the clinics were observed. Data-gathering was done through a clinic inventory obtained by interviewing the sister-incharge, observation of professional nurses providing treatment to STD patients, interviews with professional nurses to assess their knowledge of the syndromic approach, and exit interviews with patients treated at the clinic. The fmdings suggest that certain areas in the STD training need to be emphasized, such as vaginal speculum and bi-manual examinations. It is recommended that certain negative aspects which hinder effective STD management, like staff shortages and lack of equipment be given attention. / Health Studies / M.A. (Health Studies)

The aetiological diagnosis of recessive non-syndromic hearing loss poses a challenge owing to marked heterogeneity and the lack of identifying clinical features. The finding that up to 50% of recessive non-syndromal genetic hearing loss among Caucasians was due to mutations in GJB2, the gene encoding Connexin 26 (Cx26) was a breakthrough, whose value as a diagnostic tool has been limited by the significant variation in the prevalence of deafness genes and loci among population groups. The significant association of the GJB6-D13S1830 deletion among individuals with one mutant GJB2 allele highlighted the need to explore population specific genetic mutations for NSHL. Although data from Sub-Saharan Africa is limited, reported studies found a high prevalence of R143W GJB2 mutation among Ghanaian, the 35delG mutation in 5 out of 139 Sudanese and a low prevalence of GJB2 variations among 385 Kenyan deaf children. The mutation spectrum of Waardenburg Syndrome (WS) in Africans has not been documented. During a visit to a School for the Deaf in the Limpopo Province of South Africa in 1997, it was noted that a high number of students came from Nzhelele sub-district. All had childhood onset hearing loss with no associated anomalies or disorders. The question arose as to whether there was a high-risk area for deafness in the Limpopo Province and what the aetiology of this hearing loss was.The main aim of this study was to investigate the role of GJB2, the GJB6-D13S1830 deletion, and the four common mitochondrial mutations, A1555G, A3243G, A7511C and A7445G, in the African hearing-impaired population of Limpopo province in South Africa, and to identify the mutation spectrum of the deafness genes found. The type and degree of hearing loss in this hearing impaired population would also be assessed. Secondly, this study sought to identify the mutations in a sibling pair with 2 clinical WS and to use the findings in a future study to establish the mutation spectrum of WS in the African population of the Limpopo province and of South Africa in general. The study was designed as a two phase study, in which phase 1 was used for hypothesis formulation and phase 2 was for hypothesis testing. While phase 1 was a descriptive retrospective case study, phase 2 was a combination of sample survey and prospective descriptive case study. In phase 1, demographic data of 361 students in two schools of the deaf in the Limpopo province was analyzed for evidence of areas of high risk populations for deafness in the province. In phase 2, a group of 182 individuals with genetic non-syndromic hearing loss (NSHL) and two siblings with clinical WS from two schools for the Deaf in the Limpopo Province of South Africa were investigated. A thorough clinical examination, audiological evaluation and urinalysis were done. Mutational screening was carried out in all 184 subjects using genomic DNA using single-strand conformation polymorphism (SSCP), multiplex polymerase chain reaction (PCR), and direct sequencing for GJB2, and Restriction Fragment-Length Polymorphism (PCR–RFLP) analysis for GJB6, and SSCP, hetero-duplex analysis, and direct sequencing of the first 8 exons of PAX3 and all of MITF for Waarenburg syndrome. Data analysis was by geographical mapping, frequency tables, tests of association with calculation of odds ratios, and binary logistic regression analysis using STATA and GIS mapping systems. The results indicate that there seem to be areas of genuine populations at risk for hearing loss in the Limpopo province of South Africa, namely Mutale and parts of Makhado and Thulamela municipalities. In Thulamela (NP343) wards 11-15, 26-30 and 31-35, and in Mutale (NP 344) wards 6-10, together accounted for 67 (18%) of participants in phase 1, and 33 (18%) of the participants in phase 2 of the study. Mutale municipality in the Vhembe 3 district gave with a projected prevalence of at least 13.14 deaf children per 100,000 African population attending the local school for the deaf. The observed hearing loss is a genetic, non-syndromic form, which is mainly severe and severe to profound, although without any clear defining configuration or shape. It is a stable, non-progressive and prelingual form of hearing loss, implying that this may be a recessive form of deafness. No identifiable environmental confounding factors or associations were identified. The deafness is not linked the common known auditory gene mutations in GJB2, the GJB6-D13S1830 deletion, or the common mitochondrial mutations A1555G, A3243G, A7511C and A7445G. Severe and profound levels of hearing loss were found in 22.8% and 75% of the cohort respectively, with the majority exhibiting flat (70.1%) or sloping (23.4%) audiograms that were commonly symmetrical (81.5%). However, as indicated, there was no clear pattern in the audiological findings overall. None of the 184 hearing impaired individuals exhibited any of the reported disease causing mutations of GJB2, including 35delG. There was, however, a high prevalence of two variants, the C>T variant at position g.3318-15 and the C>T variant at position g.3318-34, occurring in 21.4% and 46.2% of the deaf cohort respectively. The same variants were found to occur in 35% and 42.6% of a normal hearing control group (n = 63) respectively, indicating that these variations are polymorphisms. In three subjects (1.63% of the cohort), a T>A homozygous variation at position g.3318-6 was detected. Its significance in the causation of NSSNHL is yet to be determined. The GJB6-D13S1830 deletion was not detected in any of the participants. None of the four mitochondrial mutations screened for were found. 4 These results indicate that GJB2 is not a significant deafness gene in the African population of the Limpopo Province of South Africa and that significant genes for non-syndromic recessive hearing loss in this population are yet to be found. The geographical clustering of deafness found in this study, combined with the lack of identifiable common associated clinical features among the subjects of this study (excluding the WS sibling pair), suggests that these subjects have a genetic recessive non-syndromal type of hearing loss. In the context of historical and cultural evidence of consanguinity in this population, a founder effect cannot be ruled out. A rare mutation, R223X, previously identified only once out of 470 WS patients, was identified in the PAX3 gene among the WS sibling pair. A novel silent change GGG>GGT at amino acid 293, was also identified. These identical findings document, for the first time, a molecular defect in WS in an African sibling pair, and confirm WS Type I in this family, which could be found in other WS type I South Africans in the Limpopo Province of South Africa. The current study demonstrated that parents of genetically hearing impaired children in these areas are able to detect hearing loss at an early age, with over 60% suspecting their children’s hearing loss below 6 months of age. A child-centered management model encompassing all the areas relevant to childhood deafness/hearing impairment, which takes into consideration the prevailing logistical and financial constraints of the available healthcare system, is proposed. The implementation of this model requires a paradigm shift from the current fragmented model of service delivery to a cohesive patient-centered approach, based on concrete data from appropriate community based research, in which all the relevant parties communicate and share resources. 5 It would achieve the goals of early detection and intervention, as well as inclusive education for all. The relevant health and education policies are already in place and the posts funded. Equitable implementation of these policies would require appropriate community based research, as well as improved communication and consultation between the various stakeholders to ensure an efficient and affordable quality healthcare service for all hearing impaired South Africans.

No description available.

This study is about evaluating the effectiveness of training in syndromic management ofSTDs. The purpose of this study was to fmd out to what extent the STD training programme had been implemented. A stratified sample of twenty-two primary health care clinics in the Port Shepstone region was used. Twenty-two professional nurses rendering STD management in the clinics were observed. Data-gathering was done through a clinic inventory obtained by interviewing the sister-incharge, observation of professional nurses providing treatment to STD patients, interviews with professional nurses to assess their knowledge of the syndromic approach, and exit interviews with patients treated at the clinic. The fmdings suggest that certain areas in the STD training need to be emphasized, such as vaginal speculum and bi-manual examinations. It is recommended that certain negative aspects which hinder effective STD management, like staff shortages and lack of equipment be given attention. / Health Studies / M.A. (Health Studies)

A study was undertaken of plants used for treatment of diabetic symptoms by traditional healers of the Eeyou Istchee Cree (Canada), Lukomir Highlanders (Bosnia & Herzegovina), and Q’eqchi’ Maya (Belize). All antidiabetic plants were ranked by syndromic importance value (SIV) based on 15 symptoms, all of which were recognized by the Cree and Maya and 8 by the Highlanders. The Cree used only 18 species, the Highlanders 41, and the Maya 150, numbers which reflect the diversity of flora in their region. Vaccinium (Ericaceae) was one of the few genera in all three regions and the only consensus genus between the Cree and Highlander study sites. The Q’eqchi’ Maya ethnobotany did not present any cross-cultural consensus genera with Cree or Highlander medicinal plants, perhaps due to major biogeographic differences. In ethnopharmacological studies, Vaccinium species and Q’eqchi’ antidiabetic plants were tested in an assay relevant to diabetes, the advanced glycation endproduct (AGE) inhibition assay. Boreal and tropical Vaccinium species were potent inhibitors of AGEs and demonstrated concentration dependent inhibition, with a half maximal inhibitory concentration (IC50) range of 5.93–100 µg/mL. Phenolic content ranged from 80.3 to 201 µg/mL in boreal samples and from 1470 to 2170 µg/mL in tropical samples. Tropical species have a greater phenolic content and AGE inhibition. Seven Q’eqchi’ antidiabetic plant species were tested and all plant extracts showed AGE-inhibition. The IC50s ranged from 40.8 to 733 µg/mL, and the most active was Tynanthus guatemalensis Donn.. Tynanthus guatemalensis IC50 was about fives times greater (less active) than the mean ± SE IC50 reported for six tropical Vaccinium species of Vaccinium (8.77 ± 0.79 μg/mL). The highest consensus and most active Maya antidiabetic plant, Tynanthus guatemalensis Donn. Sm. was discovered to be an important plant recorded in archeological artifacts from the Late Classic Maya period (~750 CE). Ancient Maya used a cross shaped sign (k’an glyph) as a decorative element on Late Classic polychrome vessels and murals. The sign was believed to be the xylem template for a plant used as a flavouring in cacao drinks. However, the plant was incorrectly identified in the literature as Pimenta dioica (L.) Merr. (common name: Allspice) based on a common name and aromatic plant quality – not from a botanical voucher specimen. Pimenta dioica wood does not have a cross shape visible in the xylem but a unique character visible after a cross section of T. guatemalensis, is the xylem's cross shape organization. Wood of T. guatemalensis' also has an "allspice" aroma. Tynanthus guatemalensis is most likely the true botanical template behind the ancient Maya k’an glyph and this finding would show the continuity of use of this medicinal plant from ancient to modern times. Vaccinium was selected for an in depth phytochemical analysis using modern metabolomic methods. Nuclear magnetic resonance (1H NMR) was used to evaluate leaf extract spectra to provide information on (1) the taxonomic identity and (2) quantities of bioactive metabolites across multiple sites. Spectra clearly differentiated leaf samples of V. angustifolium, V. boreale, V. corymbosum, V. macrocarpon, V. myrtilloides, V. myrtillus, V. ovalifolium, and V. uliginosum according to generic, subgeneric, specific, phenotypic circumscriptions. Quantification of chlorogenic acid and hyperoside were replicated with a method that is highly reproducible across multiple sites with different NMR equipment. This methodology provides an important new approach to taxonomy and quality control for plants and natural health products.

A study was undertaken of plants used for treatment of diabetic symptoms by traditional healers of the Eeyou Istchee Cree (Canada), Lukomir Highlanders (Bosnia & Herzegovina), and Q’eqchi’ Maya (Belize). All antidiabetic plants were ranked by syndromic importance value (SIV) based on 15 symptoms, all of which were recognized by the Cree and Maya and 8 by the Highlanders. The Cree used only 18 species, the Highlanders 41, and the Maya 150, numbers which reflect the diversity of flora in their region. Vaccinium (Ericaceae) was one of the few genera in all three regions and the only consensus genus between the Cree and Highlander study sites. The Q’eqchi’ Maya ethnobotany did not present any cross-cultural consensus genera with Cree or Highlander medicinal plants, perhaps due to major biogeographic differences. In ethnopharmacological studies, Vaccinium species and Q’eqchi’ antidiabetic plants were tested in an assay relevant to diabetes, the advanced glycation endproduct (AGE) inhibition assay. Boreal and tropical Vaccinium species were potent inhibitors of AGEs and demonstrated concentration dependent inhibition, with a half maximal inhibitory concentration (IC50) range of 5.93–100 µg/mL. Phenolic content ranged from 80.3 to 201 µg/mL in boreal samples and from 1470 to 2170 µg/mL in tropical samples. Tropical species have a greater phenolic content and AGE inhibition. Seven Q’eqchi’ antidiabetic plant species were tested and all plant extracts showed AGE-inhibition. The IC50s ranged from 40.8 to 733 µg/mL, and the most active was Tynanthus guatemalensis Donn.. Tynanthus guatemalensis IC50 was about fives times greater (less active) than the mean ± SE IC50 reported for six tropical Vaccinium species of Vaccinium (8.77 ± 0.79 μg/mL). The highest consensus and most active Maya antidiabetic plant, Tynanthus guatemalensis Donn. Sm. was discovered to be an important plant recorded in archeological artifacts from the Late Classic Maya period (~750 CE). Ancient Maya used a cross shaped sign (k’an glyph) as a decorative element on Late Classic polychrome vessels and murals. The sign was believed to be the xylem template for a plant used as a flavouring in cacao drinks. However, the plant was incorrectly identified in the literature as Pimenta dioica (L.) Merr. (common name: Allspice) based on a common name and aromatic plant quality – not from a botanical voucher specimen. Pimenta dioica wood does not have a cross shape visible in the xylem but a unique character visible after a cross section of T. guatemalensis, is the xylem's cross shape organization. Wood of T. guatemalensis' also has an "allspice" aroma. Tynanthus guatemalensis is most likely the true botanical template behind the ancient Maya k’an glyph and this finding would show the continuity of use of this medicinal plant from ancient to modern times. Vaccinium was selected for an in depth phytochemical analysis using modern metabolomic methods. Nuclear magnetic resonance (1H NMR) was used to evaluate leaf extract spectra to provide information on (1) the taxonomic identity and (2) quantities of bioactive metabolites across multiple sites. Spectra clearly differentiated leaf samples of V. angustifolium, V. boreale, V. corymbosum, V. macrocarpon, V. myrtilloides, V. myrtillus, V. ovalifolium, and V. uliginosum according to generic, subgeneric, specific, phenotypic circumscriptions. Quantification of chlorogenic acid and hyperoside were replicated with a method that is highly reproducible across multiple sites with different NMR equipment. This methodology provides an important new approach to taxonomy and quality control for plants and natural health products.