Thesis (MSc)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: The World Health Organisation (WHO) has defined preterm labour as the onset of labour before
37 completed weeks of gestation with an incidence ranging between 5-10%. Although patient
care has improved, the rate of preterm birth has slowly been increasing and currently impacts
significantly on maternal and fetal mortality and morbidity. The complex condition of preterm
labour involves multiple etiologies and risk factors, which complicates the search for candidate
markers and / or biomarkers.
The aim of this prospective study was to investigate potential genetic associations with preterm
labour. The study cohort consisted of consecutive first-time booking, low-risk primigravid
pregnant women from a restricted geographical region.
The study cohort comprised 421 [306 Coloured and 115 Black] pregnant women presenting at the
Paarl Hospital Obstetric clinic. Subsequently, DNA was extracted from whole blood and
investigated for a range of known polymorphisms in pro-inflammatory and anti-inflammatory
cytokines, as well as the novel LGALS13 gene, for potential variants that may impact on
pregnancy outcome. Screening techniques involve combinations of allele-specific PCR
amplification, Multiphor SSCP/HD analysis, restriction enzyme analyses and DNA sequencing.
A significant association was demonstrated between the IL-1RN*2-allele and adverse pregnancy
outcome, mainly in the preterm labour and hypertension group. The presence TNFα-308 A-allele
was associated with overall adverse pregnancy outcome and preterm labour. In addition to this, a
novel IL-1RN allele was identified in the control group.
Mutation screening and subsequent statistical methods revealed an association between a novel
LGALS13 exonic variant, 221delT, and preterm labour in Coloured women. Two previouslydocumented
intronic variants (IVS2-22A/G and IVS3+72T/A) demonstrated linkage
disequilibrium, signifying evolutionary conservation of exon three. Additionally, two novel
intronic variants, IVS2-36 G/A and IVS2-15 G/A, demonstrated no association with adverse
pregnancy outcome. In this study we identified rare novel exonic variants; two non-synonymous variants in exon three
(M44V, [N=2] and K87R, [N=1]) and a silent variant in exon four (P117P, [N=1]) - all identified
in individuals from the control cohort. Within coding exon three, an interesting variant
[“hotspot”] was identified, which represents six polymorphic bases within an 11bp stretch. No
associations were demonstrated with these variants and pregnancy outcome.
Furthermore, a previously documented 5' “‘promoter” variant, -98 A/C, was identified and
demonstrated no association with adverse pregnancy outcome. However, subdivision of lateonset
pre-eclamptic cases revealed a significant association with the A-allele and late-onset preeclampsia.
Genotype-phenotype investigation demonstrated association between the IL-10 -1082 A/G, IL-4
C/T and 221delT loci and poor pregnancy progress which manifested as (i) delivery of infants
weighing <2000g, (ii) before 37 weeks of gestation.
The findings of this study will strengthen our understanding of the pathophysiology underlying
pregnancy complications and facilitate the further development of effective treatment strategies to
reduce maternal and fetal morbidity and mortality. / AFRIKAANSE OPSOMMING: Die Wêreld Gesondheid Organisasie (WHO) klassifiseer voortydse kraam as kontraksie voor 37
volledige weke, met ‘n insidensie tussen 5-10%. Alhoewel pasiënte-sorg verbeter het, neem die
tempo van voortydse geboorte steeds toe, wat ‘n groot impak het op moederstrefte en fetale
mortaliteit en morbiditeit. Die komplekse kondisie van voortydse kraam sluit veelvoudige
oorsake en risiko faktore in, wat die navorsing van kandidaat en / of biologiese merkers
kompliseer.
Die doel van hierdie prospektiewe studie, was die potensiële navorsing van genetiese assosiasies
met voortydse kraam. Die studie kohort bevat opeenvolgende eerste bespreking van lae risiko
primigravida swanger vrouens vanaf ‘n beperkte geografiese omgewing.
Die studie kohort beslaan 421 [306 Kleurling en 115 Swart] swanger vrouens teenwoordig by die
Paarl Hospitaal Verloskunde kliniek. Vervolgens was DNS geëkstraeer van bloedmonsters en
geondersoek vir ‘n verskeidenheid van bekende polimorfismes in pro-inflammatoriese en antiinflammatoriese
sitokiene, insluitend die nuwe sifting van die LGALS13 geen potensiaal vir
variante wat ‘n impak op swangerskap uitkomste sal hê. Die siftings tegnieke toegepas, sluit in ‘n
kombinasie van alleel-spesifieke amplifikasie, Multiphor enkelstring konformasie polimorfisme /
heterodupleks analise, restriksie ensiem verterings en volgorde bepalings tegnieke.
‘n Betekenisvolle assosiasie was gedemonstreer tussen die IL-1RN*2-alleel en nadelige
swangerskap, beperk tot voortydse kraam en die hipertensie groep. Die teenwoordigheid van die
TNFα-308 A-alleel was geassosieer met algehele nadelige uitkomste en voortydse kraam.
Daarby, was ‘n nuwe IL-1RN alleel geïdentifiseer in die kontrole groep.
Mutasie sifting en opeenvolgende statistiese metodes, het ‘n assosiasie getoon tussen ‘n nuwe
LGALS13 koderende variant, 221delT, en voortydse kraam in Kleurling vrouens. Twee
voorafbeskryfde introniese variante (IVS2-22 A/G en IVS3+72 T/A), het ‘n betekenisvolle bewys
opgelewer dat daar koppelings-onewewig bestaan tussen hierdie variante, en toon evolusionêre konservasie van ekson drie. Addisioneel was twee nuwe introniese variante ontdek, IVS2-36 G/A
en IVS2-15 G/A, wat geen assosiasie getoon nie.
In hierdie studie het ons ‘n nuwe seldsame koderende variante geïdentifiseer in die kontrole
groep, waarvan twee nie-sinonieme variante was in ekson drie (M44V, N=2 en K87R, N=1) en ‘n
stil variasie in ekson vier (P117P, N=1). Geleë in die koderende area van ekson drie, was ’n
interessante variant [“hotspot’] ontdek, waarvan ses basisse in ‘n 11 basis paar area polimorfies
is. Geen assosiasie was getoon met hierdie variante en swangerskap uitkomste nie.
Verder was ‘n voorafbeskryfde 5' ‘promotor’ variant, -98 A/C, geïdentifiseer wat geen assosiasie
getoon met nadelige swangerskap uitkomste nie. Onderverdeling van laat-aanvangs preeklampsie,
het getoon dat die A-alleel ‘n betekenisvolle assosiasie getoon het met die
ontwikkeling van laat pre-eklampsie.
Genotipe-fenotipe interaksies het ’n assosiasie getoon tussen die IL-10 -1082 A/G, IL-4 C/T en
221delT lokusse en nadelige swangerskap uitkomste, wat manifesteer as (i) kraam van suigelinge
wat <2000g weeg, (ii) geboorte voor 37 weke.
Die bevindings van hierdie studie sal ons basiese kennis verbeter oor die patologie beskrywend
aan swangerskap komplikasies, asook die fasilitering en ontwikkeling van effektiewe
behandelings strategieë, om moederstrefte en fetale mortaliteit en morbiditeit te verminder.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/17741 |
| Date | 12 1900 |
| Creators | Bruiners, Natalie |
| Contributors | Hillermann-Rebello, R., Gebhardt, G. S., Stellenbosch University. Faculty of Agrisciences. Dept. of Genetics. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xxix, 164 leaves : ill. |
| Rights | Stellenbosch University |
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