Dear Khaled,

The following publication demonstrates the existence of exon skipping on enzyme:

FEBS Lett. 2001 Jul 20;501(2-3):135-8.

Splice donor site mutation in the lysosomal neuraminidase gene causing exon skipping and complete loss of enzyme activity in a sialidosis patient.

Penzel R1, Uhl J, Kopitz J, Beck M, Otto HF, Cantz M.

Abstract

Sialidosis is a lysosomal storage disease caused by the deficiency of alpha-N-acetylneuraminidase (NEU1; sialidase), the key enzyme for the intralysosomal catabolism of sialylated glycoconjugates. We have identified a homozygous transversion in the last intron (IVSE +1 G>C) in neu1 of a sialidosis patient. Sequencing of the truncated cDNA revealed an alternatively spliced neu1 transcript which lacks the complete sequence of exon 5. Skipping of exon 5 leads to a frameshift and results in a premature termination codon. This is the first description of an intronic point mutation causing a complete deficiency of the lysosomal neuraminidase activity.

http://www.ncbi.nlm.nih.gov/pubmed/11470272

Hoping this will be helpful,

Rafik

thank you