The congenital disorders of glycosylation (CDGs) are genetic disorders affecting the N-glycosylation process. CDGs are divided into defects in the synthesis of N-glycans (CDG-I) and defects in the processing of N-glycans (CDG-II). CDG-IIb is caused by mutations in the gene encoding MOGS (also known as glucosidase 1).
An 11-year-old boy and 6-year-old girl, first and third children, born to a young, healthy, non-consanguineous couple were evaluated. They are characterized by dysmorphic features, hypotonia, seizures, global developmental delay, cerebral atrophy, optic nerve atrophy, hearing loss, and recurrent bone fractures; severe hypogammaglobulinemia was also diagnosed.
The patients had no complications after routine vaccinations, including live viral vaccines.
What is hypogammaglobulinemia?
Hypogammaglobulinemia is a type of primary immune deficiency disease.
The siblings had normal or increased numbers of B cells in peripheral blood but severe hypogammaglobulinemia (317 mg/dL and 142 mg/dL) with significantly shortened half-life for IgG (6 days). The patients had normal specific antibody response to polysaccharide proteins, conjugated proteins, and polysaccharide antigens but did not respond to live virus vaccines such as measles-mumps-rubella (vaccine) or varicella, which are viruses with glycosylated envelopes.
These data seem to suggest that altered glycosylation may modify the susceptibility to infection with viruses that must undergo protein glycosylation to complete their infection cycle. This study helps us to continue to expand our understanding of genetically determined permutations of host defense that could aid in explaining these unusual and unanticipated clinical presentations.
What is glycosylation?
Most proteins, including immunoglobulins, human virus receptors, and viral-coded proteins, are post-translationally modified with sugars or sugar chains that are generically referred to as glycans. Glycans are primarily classified as N-linked or O-linked oligosaccharides.
Both patients were evaluated through the National Institutes of Health.On the basis of the biochemical and genetic findings, the siblings were given a diagnosis of CDG-IIb
These patients did not have altered susceptibility to adenovirus or parvovirus 1, which are nonenvelope viruses, or to vaccinia virus, which is an envelope virus. In contrast, the patients did have markedly reduced susceptibility to infection with HIV and influenza viruses, which are glycosylation-dependent envelope viruses.
There are not cases studied in Ecuador.
CDGs In Latinoameric