Related Experiment Videos
Four novel mutations underlying mild or intermediate forms of alpha-L-iduronidase deficiency (MPS IS and MPS IH/S)
1Department of Biological Chemistry, UCLA School of Medicine 90024-1737, USA.
Abstract:
The alpha-L-iduronidase deficiency diseases (Mucopolysaccharidosis I) cover a spectrum of clinical severity ranging from the very severe (Hurler syndrome, MPS IH) through an intermediate (Hurler/Scheie syndrome, MPS IH/S) to a relatively mild form (Scheie syndrome, MPS IS). Numerous mutations of the gene encoding alpha-L-iduronidase (IDUA) are known in Hurler syndrome, but only three in the other disorders. We report on novel mutations of the IDUA gene in one patient with the Scheie syndrome and in three patients with the Hurler/Scheie syndrome. The novel mutations, all single base changes, encoded the substitutions R492P (Scheie), and X654G, P496L, and L490P (Hurler/Scheie). The L490P mutation was apparently homozygous, whereas each of the others was found in compound heterozygosity with a Hurler mutation. The deleterious nature of the mutations was confirmed by absence of enzyme activity upon transfection of the corresponding mutagenized cDNAs into Cos-1 cells. These results provide additional information for genotype-phenotype correlations.
Insights
This study identifies novel mutations in the alpha-L-iduronidase (IDUA) gene in patients with Scheie syndrome and Hurler/Scheie syndrome, expanding knowledge of mucopolysaccharidosis I genetic causes.
Area of Science:
- Biochemistry
- Genetics
- Molecular Biology
Background:
- Mucopolysaccharidosis I (MPS I) encompasses a spectrum of alpha-L-iduronidase deficiency diseases, including Hurler, Hurler/Scheie, and Scheie syndromes.
- While numerous mutations in the alpha-L-iduronidase (IDUA) gene are known for Hurler syndrome, only a few have been identified for milder forms.
- Understanding genotype-phenotype correlations is crucial for diagnosing and managing MPS I.
Observation:
- This research reports on novel mutations within the IDUA gene identified in patients diagnosed with Scheie syndrome and Hurler/Scheie syndrome.
- Specific novel mutations identified include R492P (Scheie syndrome), and X654G, P496L, and L490P (Hurler/Scheie syndrome).
- Functional studies involving cDNA transfection into Cos-1 cells confirmed the deleterious effect of these mutations due to the absence of enzyme activity.
Findings:
- Four novel single-base mutations in the IDUA gene were discovered: R492P, X654G, P496L, and L490P.
- The L490P mutation was observed in a homozygous state, while R492P, X654G, and P496L were found in compound heterozygosity with known Hurler mutations.
- Experimental validation demonstrated that these mutations lead to a loss of alpha-L-iduronidase enzyme activity.
Implications:
- These findings contribute valuable data for refining genotype-phenotype correlations in mucopolysaccharidosis I.
- The identification of new mutations expands the known mutational spectrum for Scheie and Hurler/Scheie syndromes.
- This research may aid in more precise genetic diagnosis and potentially inform future therapeutic strategies for MPS I.