All the cells of blood arise from two lineages, the myeloid and the lymphoid lineage.
The various cells of blood perform vital functions in the body. These cell counts are
closely regulated by regulatory pathways. Mutations within genes that encode for the
proteins involved in these pathways can occur. These mutations can cause
uncontrolled proliferation of the cells. Myeloproliferative neoplasms are malignancies
where there is an uncontrolled increase in the formation of the myeloid cells. The four
classical neoplasms are polycythaemia vera, essential thrombocythaemia, primary
myelofibrosis and chronic myeloid leukaemia.
A mutation (V617F) in the tyrosine kinase, Janus kinase 2, has been found to be the
cause of at least three of the classical MPNs. The mutation lies in the domain of the
protein that controls its tyrosine kinase activity. The tyrosine kinase thus is
constitutively active and causes proliferation of the myeloid cells. The V617F mutation
lies in exon 14 and more recently several mutations have been described in the
neighbouring exons encoding for the regulatory domain of the gene. Very few studies
have been done on the other exons of the JAK 2 gene.
In the study it was attempted to screen 15 MPN patients for mutations in the JAK 2
gene. Two different cell populations (lymphocytes and granulocytes) of each patient
were screened. It was found that the cell purity was not sufficient in the study and
better separation techniques are required for future studies. Only the granulocytes were
used for the remainder of the study. High resolution melting curve analysis was used to
screen the patients for mutations, however the data did not correlate with the
sequencing results and it was decided to proceed with sequencing of all the samples. Seven of the 25 exons of the JAK 2 gene were successfully sequenced. The remaining
exons could not be screened due to time constraints and complications such as multiple
amplicon formation. Two previously reported single nucleotide polymorphisms were
found in exons 11 and 15 in two patients. The clinical significance thereof is uncertain
however, the patient whom had the SNP in exon 15 was negative for the V617F
mutation and had a MPN. In exon 14 the V617F mutation was identified and the
prevalence thereof correlates to that reported in literature. A novel SNP was found in
exon 13 of a PV patient negative for the V617F mutation and the significance thereof is
also uncertain. Additionally a novel inverse duplication consisting of at least of exon 13
was also identified. No mutations were identified in exons 10, 12, 16 and 17 of the JAK
2 gene.
This was, to our knowledge, the first report in South Africa that found the prevalence of
the V617F mutation in MPN patients correlating to the prevalence reported in literature.
A novel SNP was identified in exon 13 and further studies are needed on the possible
effect thereof. The previously reported SNPs found in exons 11 and 15 might be the
cause of the formation of a MPN, however further research is needed. A novel
duplication variant was also identified and this might be a possible splice variant. The
study showed that the region between exons 10 and 15 in the JAK 2 gene is a
mutational hotspot and further studies are needed to elucidate the effect thereof.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-08232012-152010 |
| Date | 23 August 2012 |
| Creators | Goodyear, Quintin Clive |
| Contributors | Prof CD Viljoen, Dr A de Kock |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-08232012-152010/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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