Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: Hirschsprung's disease, or aganglionic megacolon, is a common cause of intestinal
obstruction in neonates and is associated with the congenital absence of intrinsic
ganglion cells in the myenteric and submucosal plexuses of the gastrointestinal tract.
The affected area is usually restricted to the distal part of the colon (short segment
disease), but total colonic or intestinal involvement occurs in some patients (long
segment disease).
DNA analysis was performed on samples from 53 unrelated sporadic HSCR patients
to search for mutations in RET proto-oncogene, endothelin-B receptor (EDNRB) and
endothelin-3 (EDN3) genes. The patients were from different ethnic groups in South
Africa, including 29 coloured, 14 white (Caucasian) and 9 black individuals. The
origin of 1 patient was unknown. PCR HEX-SSCP analysis of the RET protooncogene
revealed one previously described (P973L) and five novel mutations
(V202M, E480K, IVS10-2A1G, D771N, IVS19-9Crr), likely to cause or contribute to
the HSCR phenotype. Nine polymorphisms were also identified in the RET protooncogene,
of which four were novel (IVS6+56deIG, IVS13-29Crr, IVS16-38deIG,
X1159) and five previously described (A45, A432, L769, S904, R982). All the mobility
shifts detected in the EDNRB gene represented polymorph isms (A60T, S184, 1187,
V234, L277, IVS3-6Crr, IVS4+3A1G). No sequence variants were identified in the
EDN3 gene. The majority of mutations in the RET proto-oncogene (28.6%) were
identified in coloured patients while no mutations were identified in black patients. A
mutation in RET was identified in two of 14 patients (14%) presenting with HSCR and
Down's syndrome compared to 6 mutations identified in 9 of 39 patients (23%) with only HSCR. The fact that Down's syndrome patients have a high chance of
developing HSCR, implies the involvement of modifier gene(s) in a HSCR/Oown's
syndrome phenotype.
This study demonstrated that, within the South African HSCR patient population, the
RET proto-oncogene is the major susceptibility gene, whereas EDNRB and EDN3
may contribute only to a minority of cases. In 81% of patients no disease-causing
mutation could be identified, which is in keeping with the heterogeneous nature of
HSCR. The identification of mutations in HSCR patients would in future lead to
improved and accurate counselling of South African HSCR patients and their
families. / AFRIKAANSE OPSOMMING: Hirschsprung se siekte (HSCR), ook bekend as aganglionosis megakolon, is 'n
algemene oorsaak van intestinale obstruksie in pasgeborenes en word geassosieer
met die kongenitale afwesigheid van intrinsieke ganglion selle, in die miênteries en
submukosa pleksus van die gastrointestinale kanaal. Alhoewel die aangetaste deel
hoofsaaklik by die distale area van die kolon geleê is (kort segment siekte), kom
totale koloniese of intestinale betrokkenheid ook in sommige pasiënte voor (lang
segment tipe).
Molekulêre ONS analise van 53 nie-verwante Suid Afrikaanse sporadiese HSCR
pasiênte (29 kleurlinge, 14 blankes, 9 swartes en 1 individu van onbekende
oorsprong) is uitgevoer in die RET proto-onkogeen, endoteel-B reseptor (EDNRB) en
endoteel-3 (EDN3) gene. Heterodupleks-enkel string konformasie polimorfisme
(HEX-SSCP) analise van polimerase ketting reaksie (PKR) geamplifiseerde produkte
van die RET proto-onkogeen het gelei tot die identifikasie van vyf nuwe mutasies
(V202M, E480K, IVS10-2A1G, D771N, IVS19-9CIT) en een bekende mutasie
(P973L). Vier nuwe polimorfismes (IVS6+56deIG, IVS13-29Crr, IVS16-38deIG,
X1159) en vyf bekende polimorfismes (A45, A432, L769, S904, R982) is ook
aangetoon. Sewe polimorfismes (A60T, S184, 1187, V234, L277, IVS3-6CIT,
IVS4+3A1G) is in die EDNRB geen geïdentifiseer. Geen veranderinge is in die EDN3
geen waargeneem nie. Die meerderheid mutasies waargeneem in die RET protoonkogeen
is in die kleurling populasie (28.6%) waargeneem, terwyl geen mutasies in
die swart populasie geïdentifiseer is nie. 'n RET mutasie is in twee van 14 (14%)
pasiênte met 'n HSCR en Down's sindroom fenotipe waargeneem, in vergelyking met mutasies geïdentifiseer in 9 van 39 pasiënte (23%) met slegs HSCR. Die algemene
voorkoms van Down's sindroom met HSCR, impliseer die rol van ander gene in die
HSCRI Down's sindroom fenotipe.
Die meerderheid mutasies wat aanleiding gee tot die HSCR fenotipe kom voor in die
RET proto-onkogeen (19%), terwyl slegs polimorfismes in die EDNRB geen
waargeneem is. Geen HEX-SSCP bandpatroon veranderinge is in die EDN3 geen
waargeneem nie. Ongeveer 81% van die Suid Afrikaanse HSCR pasiënte was
mutasie-negatief wat dui op die heterogene aard van die siekte. In die toekoms sal
analise van siekte-verwante mutasies in die RET geen lei tot akkurate diagnose en
verbeterde genetiese voorligting van HSCR in die Suid-Afrikaanse populasie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/51835 |
| Date | 03 1900 |
| Creators | Julies, Monique G. |
| Contributors | Moore, S. W., Kotze, M. J., Du Plessis, L., Stellenbosch University. Faculty of Medicine & Health Sciences. Dept. of Pathology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 106 p. : ill. |
| Rights | Stellenbosch University |
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