Abnormal glycosylation in Joubert syndrome type 10.
BACKGROUND
The discovery of disease pathogenesis requires systematic agnostic screening of multiple homeostatic processes that may become deregulated. We illustrate this principle in the evaluation and diagnosis of a 5-year-old boy with Joubert syndrome type 10 (JBTS10). He carried the OFD1 mutation p.Gln886Lysfs*2 (NM_003611.2: c.2656del) and manifested features of Joubert syndrome.


METHODS
We integrated exome sequencing, MALDI-TOF mass spectrometry analyses of plasma and cultured dermal fibroblasts glycomes, and full clinical evaluation of the proband. Analyses of cilia formation and lectin staining were performed by immunofluorescence. Measurement of cellular nucleotide sugar levels was performed with high-performance anion-exchange chromatography with pulsed amperometric detection. Statistical analyses utilized the Student's and Fisher's exactttests.


RESULTS
Glycome analyses of plasma and cultured dermal fibroblasts identified abnormalN- andO-linked glycosylation profiles. These findings replicated in two unrelated males withOFD1mutations. Cultured fibroblasts from affected individuals had a defect in ciliogenesis. The proband's fibroblasts also had an abnormally elevated nuclear sialylation signature and increased total cellular levels of CMP-sialic acid. Ciliogenesis and each glycosylation anomaly were rescued by expression of wild-typeOFD1.


CONCLUSIONS
The rescue of ciliogenesis and glycosylation upon reintroduction of WTOFD1suggests that both contribute to the pathogenesis of JBTS10.
NIH Undiagnosed Disease Program, Common Fund, Office of the Director, and National Human Genome Research Institute, National Institutes of Health, Bethesda, MD USA.|Inova Translational Medicine Institute, Inova Health System, Falls Church, VA USA.
Megan S
MS
Kane
NIH Undiagnosed Disease Program, Common Fund, Office of the Director, and National Human Genome Research Institute, National Institutes of Health, Bethesda, MD USA.
Mariska
M
Davids
National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD USA.
Michelle R
MR
Bond
NIH Undiagnosed Disease Program, Common Fund, Office of the Director, and National Human Genome Research Institute, National Institutes of Health, Bethesda, MD USA.
Christopher J
CJ
Adams
Department of Pediatrics, University of Washington, Seattle, WA USA.
Megan E
ME
Grout
Department of Pediatrics, University of Washington, Seattle, WA USA.
Ian G
IG
Phelps
Department of Pediatrics, University of Washington, Seattle, WA USA.
Diana R
DR
O'Day
Department of Pediatrics, University of Washington, Seattle, WA USA.
Jennifer C
JC
Dempsey
The Michael J Palmieri Metabolic Laboratory, Children's Hospital of Philadelphia, Philadelphia, PA USA.
Xeuli
X
Li
NIH Undiagnosed Disease Program, Common Fund, Office of the Director, and National Human Genome Research Institute, National Institutes of Health, Bethesda, MD USA.
Gretchen
G
Golas
Children's National Medical Center, Washington, DC USA.
Gilbert
G
Vezina
Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD USA.|Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD USA.|Johns Hopkins University School of Medicine, Department of Pediatrics and McKusick-Nathans Institute of Genetic Medicine, Baltimore, MD USA.
Meral
M
Gunay-Aygun
National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD USA.
John A
JA
Hanover
Department of Pediatrics, University of Washington, Seattle, WA USA.
Dan
D
Doherty
The Michael J Palmieri Metabolic Laboratory, Children's Hospital of Philadelphia, Philadelphia, PA USA.
Miao
M
He
NIH Undiagnosed Disease Program, Common Fund, Office of the Director, and National Human Genome Research Institute, National Institutes of Health, Bethesda, MD USA.
May Christine V
MCV
Malicdan
NIH Undiagnosed Disease Program, Common Fund, Office of the Director, and National Human Genome Research Institute, National Institutes of Health, Bethesda, MD USA.
William A
WA
Gahl
NIH Undiagnosed Disease Program, Common Fund, Office of the Director, and National Human Genome Research Institute, National Institutes of Health, Bethesda, MD USA.|Department of Medical Genetics, University of British Columbia, Vancouver, BC Canada.
Cornelius F
CF
Boerkoel
CMP-sialic acid; Ciliopathy; Glycosylation; Joubert syndrome; Molar tooth sign