Mucolipidosis II-III (I-Cell disease)
Definition
Mucolipidosis II (I-cell disease) and type III alpha/beta result from biallelic variants in the GNPTAB gene, which encodes the subunits of N-acetylglucosamine-1-phosphotransferase required for mannose-6-phosphate tagging of lysosomal enzymes. Enzyme deficiency disrupts the targeting of lysosomal enzymes to lysosomes, causing accumulation of inclusion material; ML II is apparent at birth and can be fatal in early childhood, while ML III is milder and later in onset.
Gene/region examined
GNPTAB - Exon 1, GNPTAB - Exon 2, GNPTAB - Exon 3, GNPTAB - Exon 4, GNPTAB - Exon 5, GNPTAB - Exon 6, GNPTAB - Exon 7, GNPTAB - Exon 8, GNPTAB - Exon 9, GNPTAB - Exon 10, GNPTAB - Exon 11, GNPTAB - Exon 12, GNPTAB - Exon 13, GNPTAB - Exon 14, GNPTAB - Exon 15, GNPTAB - Exon 16, GNPTAB - Exon 17, GNPTAB - Exon 18, GNPTAB - Exon 19, GNPTAB - Exon 20, GNPTAB - Exon 21
Method
Sequence analysis
Accepted sample types
EDTA blood, AF, CVS
Inheritance
Hereditary, autosomal recessive.