Sanfilippo syndrome type D in two adolescent sisters.

Area of Science:

• Biochemistry
• Genetics
• Rare Diseases

Background:

• Sanfilippo syndrome type D is a rare genetic disorder.
• It is characterized by the accumulation of specific glycosaminoglycans.
• Deficiency in N-acetylglucosamine-6-sulphate sulphatase (GlcNAc-6S sulphatase) is the hallmark of type D.

Observation:

• Two adolescent sisters presented with Sanfilippo syndrome type D.
• They exhibited distinct clinical features compared to previously described cases.
• These patients represent the oldest reported cases of this syndrome to date.

Findings:

• Fibroblast analysis confirmed a deficiency in GlcNAc-6S sulphatase enzyme activity and immunoreactivity.
• Northern blot analysis revealed normal messenger RNA (mRNA) levels for the GlcNAc-6S sulphatase gene.
• This discrepancy points towards post-transcriptional or post-translational mechanisms causing the enzyme defect.

Implications:

• These findings suggest that abnormal protein translation or premature degradation of the enzyme may underlie the observed GlcNAc-6S sulphatase deficiency.
• The study provides novel insights into the molecular pathology and clinical variability of Sanfilippo syndrome type D.
• Understanding these mechanisms could inform future therapeutic strategies for this rare lysosomal storage disorder.