Mosaicism of the UDP-galactose transporter SLC35A2 causes a congenital disorder of glycosylation

Am J Hum Genet. 2013 Apr 4;92(4):632-6. doi: 10.1016/j.ajhg.2013.03.012.


Biochemical analysis and whole-exome sequencing identified mutations in the Golgi-localized UDP-galactose transporter SLC35A2 that define an undiagnosed X-linked congenital disorder of glycosylation (CDG) in three unrelated families. Each mutation reduced UDP-galactose transport, leading to galactose-deficient glycoproteins. Two affected males were somatic mosaics, suggesting that a wild-type SLC35A2 allele may be required for survival. In infancy, the commonly used biomarker transferrin showed abnormal glycosylation, but its appearance became normal later in childhood, without any corresponding clinical improvement. This may indicate selection against cells carrying the mutant allele. To detect other individuals with such mutations, we suggest transferrin testing in infancy. Here, we report somatic mosaicism in CDG, and our work stresses the importance of combining both genetic and biochemical diagnoses.

Publication types

  • Case Reports
  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport
  • Case-Control Studies
  • Child
  • Child, Preschool
  • Congenital Disorders of Glycosylation / etiology*
  • Congenital Disorders of Glycosylation / metabolism
  • Congenital Disorders of Glycosylation / pathology
  • Exome / genetics
  • Female
  • Glycosylation
  • Humans
  • Male
  • Monosaccharide Transport Proteins / genetics*
  • Mosaicism*
  • Mutation / genetics*
  • Spectrometry, Mass, Electrospray Ionization
  • Transferrin / analysis
  • Transferrin / metabolism
  • Uridine Diphosphate Galactose / metabolism*


  • Monosaccharide Transport Proteins
  • Transferrin
  • UDP-galactose translocator
  • Uridine Diphosphate Galactose