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Structural gene aberrations in mucopolysaccharidosis II (Hunter)
M Wehnert1, J J Hopwood, W Schröder
1Institut für Medizinische Genetik, Ernst Moritz Arndt-Universität, Greifswald, Federal Republic of Germany.
Human Genetics
|June 1, 1992
Summary
Southern analysis revealed gene deletions and point mutations in German patients with Hunter syndrome (MPS II). One patient showed a complete loss of the IDS gene, while another had a new restriction site due to a point mutation.
Area of Science:
- Genetics
- Molecular Biology
- Biochemistry
Background:
- Hunter syndrome, also known as mucopolysaccharidosis type II (MPS II), is an X-linked genetic disorder caused by deficiency of the enzyme iduronate-2-sulfatase (IDS).
- Clinical manifestations of Hunter syndrome are variable, ranging from mild to severe.
- Understanding the genetic basis of IDS deficiency is crucial for diagnosis and potential therapeutic strategies.
Purpose of the Study:
- To investigate structural gene aberrations in German patients with X-linked iduronate-2-sulfatase (IDS) deficiency (Hunter syndrome, MPS II).
- To identify specific genetic alterations, such as deletions or point mutations, within the IDS gene.
- To correlate identified gene aberrations with the clinical variability observed in patients.
Main Methods:
- Southern blot analysis was performed on DNA from 14 unrelated German patients diagnosed with Hunter syndrome.
- An IDS cDNA clone (c2S15) was used as a probe to detect structural gene aberrations.
- Analysis included DNA digestion with restriction enzymes HindIII, PstI, and TaqI, and testing of flanking loci (DXS 297, DXS 296, DXS 466).
Main Results:
- Patient G-65, severely affected, showed no detectable Southern fragments, suggesting a total loss of the IDS structural gene. The deletion involved the flanking locus DXS 466.
- Patient G-117 exhibited a disappearance of a normal 9.0-kb fragment and the appearance of an aberrant 3.5-kb fragment in HindIII digests, indicative of a point mutation.
- Normal Southern patterns were observed for PstI and TaqI digests in patient G-117, and for PstI and TaqI in patient G-65 (for the tested loci).
Conclusions:
- Southern analysis is effective in detecting gross structural gene aberrations like deletions in the IDS gene.
- A total loss of the IDS structural gene was identified in a severely affected patient, associated with a deletion at the DXS 466 locus.
- A point mutation creating an additional HindIII restriction site within an IDS gene intron was identified in another patient, contributing to Hunter syndrome.