So far the clinical phenotype of only one CDG-Ij patient has been described. The patient showed severe muscular hypotonia, intractable seizures, developmental delay, mental retardation, microcephaly and exotropia. Molecular studies of this patient revealed the heterozygous mutation c.660A > G (Y170C; paternal) in combination with an uncharacterized splicing defect (maternal). Two further mutations, c.890A > T (I297F) and c.162-8 G > A as a splicing defect were detected when analyzing DPAGT1 in two affected siblings of a second family.
We report two new patients with the novel homozygous mutation, c.341 C > G (A114G), causing a severe clinical phenotype, characterized by hyperexcitability, intractable seizures, bilateral cataracts, progressive microcephaly and muscular hypotonia. Both our patients died within their first year of life.
With the discovery of this novel mutation and a detailed clinical description we extend the clinical features of CDG-Ij in order to improve early detection of this disease.