Mosaicism of the UDP-Galactose transporter SLC35A2 in a female causing a congenital disorder of glycosylation: a case report.

Source:   BMC Med. Genet. 2018 Jun 15 . 19 ( 1 ) : 100 . doi: 10.1186/s12881-018-0617-6 . 2018 06 15
PMID: 29907092
DOI: 10.1186/s12881-018-0617-6

ABSTRACT

BACKGROUND

Congenital disorders of glycosylation are rare conditions caused by genetic defects in glycan synthesis, processing or transport. Most congenital disorders of glycosylation involve defects in the formation or transfer of the lipid-linked oligosaccharide precursor of N-linked glycans. SLC35A2-CDG (previously CDG-IIm) is caused by hemizygous or heterozygous mutations in the X-linked gene SLC35A2 that encodes a UDP-galactose transporter. To date there have only been 10 reported patients with SLC35A2 mutations. Importantly, the patient presented here was not identified in infancy by transferrin isoform analysis, the most common testing to identify patients with a congenital disorder of glycosylation.

CASE PRESENTATION

A 27 month old girl with developmental delay, central hypotonia, cerebral atrophy, and failure to thrive with growth retardation was identified by whole exome sequencing to have a mosaic missense variant in SLC35A2 (c.991G > A). This particular variant has been previously reported in a male as a mutation. Comparison of all clinical findings and new information on growth pattern, growth hormone testing and neurodevelopmental evaluation are detailed on the patient presented.

CONCLUSION

This patient report increases the clinical and scientific knowledge of SLC35A2-CDG, a rare condition. New information on reduced growth, growth hormone sufficiency, lack of seizures, and neurodevelopmental status are presented. This new information will be helpful to clinicians caring for individuals with SLC35A2-CDG. This report also alerts clinicians that transferrin isoform measurements do not identify all patients with congenital disorders of glycosylation.

Author information
  1. Department of Pediatrics, University of Minnesota, 2450 Riverside Avenue, Minneapolis, MN, 55454, USA.
  2. Divisions of Endocrinology, Genetics & Metabolism, University of Minnesota, 2450 Riverside Avenue, Minneapolis, MN, 55454, USA.
  3. Department of Neurology, Gillette Children's Hospital, 200 University Avenue East, St. Paul, MN, 55101, USA.
  4. Division of Clinical Behavioral Neuroscience, Department of Pediatrics, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN, 55455-0392, USA.
  5. University of Minnesota Masonic Children's Hospital, 2450 Riverside Avenue, Minneapolis, MN, 55454, USA.
  6. Department of Radiology, University of Minnesota, 420 Delaware St. SE, Minneapolis, MN, 55455, USA.
  7. Molecular Diagnostics Laboratory, University of Minnesota Medical Center, 420 Delaware St SE, Minneapolis, MN, 55455, USA.
  8. Division of Genetics & Metabolism, Department of Pediatrics and Ophthalmology, 2450 Riverside Avenue, Minneapolis, MN, 55454, USA. pierp001@umn.edu.
KEYWORDS:
Congenital disorder of glycosylation , Growth failure , SLC35A2 mutation , Transferrin isoforms , Whole exome sequencing .
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