Backround. Congenital disorders of glycosylation (CDG syndrome) represent a newly delineated group of inherited
diseases of glycoprotein synthesis. We present results of biochemical and molecular analyses in two Czech patients
with CDG Ia syndrome.
Methods andResults. Serumconcentrations of the nonglycosylated and hypoglycosylated transferrinweremeasured
using turbidimetric immunoassay. In positive patients, the isoelectric focusing of serum transferrin and molecular
analyses of the gene for phosphomannomutase 2 were performed. The disease manifested in both children in infancy
with failure to thrive, inverted nipples, strabismus, epilepsy, muscle hypotonia, microcephaly, psychomotor retardation
and hypoplasia of the cerebellum. The biochemical investigation revealed elevated liver enzymes, low
concentration of factor XI and protein S. In one child lower concentration of the antithrombin III and protein C were
found. Activities of arylsulfatase A and β-glucuronidase in serum were higher and activity of α-mannosidase in
leucocytes was lower in comparison with controls. Molecular analyses revealed that both children are compound
heterozygotes for the mutation 422G>A and 357C>A in gene for phosphomanomutase 2. Both siblings are also
homozygotes for polymorfism IVS5+19 C →T and heterozygygotes for polymorfism IVS5+22 T→A.
Conclusions, The prognosis of children with CDG Ia is unfavourable. Enzymatic and/or molecular studies are
necessary for genetic counselling and the prenatal diagnosis.
CDG Ia, psychomotor retardation, failure to thrive, cerebellar hypoplasia.