Mucopolysaccharidosis IVA within Tunisian patients: Confirmation of the two novel GALNS gene mutations.

UNLABELLED: Mucopolysaccharidosis type IVA or Morquio A disease is an autosomal recessive disease resulting from a deficiency of the lysosomal enzyme N-acetylgalactosamine-6-sulfate-sulfatase, which hydrolyses N-acetylgalactosamine-6-sulfate and galactose-6-sulfate in glycosaminoglycans. Phenotypes in Morquio A disease vary from the classical form with severe bone dysplasia, heart valve involvement, corneal opacity, short trunk dwarfism and a life span of 20 to 30 years, to attenuated forms with normal life span, mild bone involvement and mild visceral organ involvement. Unlike the other forms of mucopolysaccharidoses, Morquio A disease is characterized by normal intelligence.

AIM OF THE STUDY: The aims of this study were to determine if the novel GALNS anomalies IVS1+1G-A and G66R identified in Tunisia are mutations or polymorphisms.

PATIENTS AND

METHODS

This study was carried out on six Morquio A patients recruited from many regions of Tunisia. We have used SCCP, sequencing and enzymatic digestion.

RESULTS

IVS1+1G-A and G66R were two deleterious mutations and not polymorphisms.

CONCLUSION

Screening of mutations and polymorphisms in GALNS gene provide useful information on genotype/phenotype correlations. It should also facilitate more accurate genetic counselling of newly diagnosed cases and their family members.