Mutations in TMEM260 Cause a Pediatric Neurodevelopmental, Cardiac, and Renal Syndrome.
Despite the accelerated discovery of genes associated with syndromic traits, the majority of families affected by such conditions remain undiagnosed. Here, we employed whole-exome sequencing in two unrelated consanguineous kindreds with central nervous system (CNS), cardiac, renal, and digit abnormalities. We identified homozygous truncating mutations in TMEM260, a locus predicted to encode numerous splice isoforms. Systematic expression analyses across tissues and developmental stages validated two such isoforms, which differ in the utilization of an internal exon. The mutations in both families map uniquely to the long isoform, raising the possibility of an isoform-specific disorder. Consistent with this notion, RT-PCR of lymphocyte cell lines from one of the kindreds showed reduced levels of only the long isoform, which could be ameliorated by emetine, suggesting that the mutation induces nonsense-mediated decay. Subsequent in vivo testing supported this hypothesis. First, either transient suppression or CRISPR/Cas9 genome editing of zebrafish tmem260 recapitulated key neurological phenotypes. Second, co-injection of morphants with the long human TMEM260 mRNA rescued CNS pathology, whereas the short isoform was significantly less efficient. Finally, immunocytochemical and biochemical studies showed preferential enrichment of the long TMEM260 isoform to the plasma membrane. Together, our data suggest that there is overall reduced, but not ablated, functionality of TMEM260 and that attenuation of the membrane-associated functions of this protein is a principal driver of pathology. These observations contribute to an appreciation of the roles of splice isoforms in genetic disorders and suggest that dissection of the functions of these transcripts will most likely inform pathomechanism.
Department of Pediatric Cardiology, Hadassah Medical Center, Jerusalem 91120, Israel.
Asaf
A
Ta-Shma
Center for Human Disease Modeling, Duke University Medical Center, Durham, NC 27701, USA.
Tahir N
TN
Khan
Department of Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA; Talpiot Medical Leadership Program, Sheba Medical Center, Tel-Hashomer, Ramat Gan 52621, Israel.
Asaf
A
Vivante
Center for Human Disease Modeling, Duke University Medical Center, Durham, NC 27701, USA.
Jason R
JR
Willer
Center for Human Disease Modeling, Duke University Medical Center, Durham, NC 27701, USA.
Pavle
P
Matak
Bonei Olam, Center for Rare Jewish Genetic Disorders, Brooklyn, NY 11204, USA.
Chaim
C
Jalas
Talpiot Medical Leadership Program, Sheba Medical Center, Tel-Hashomer, Ramat Gan 52621, Israel; Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Ramat Gan 52621, Israel; Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv 6997801, Israel.
Ben
B
Pode-Shakked
Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Ramat Gan 52621, Israel; Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv 6997801, Israel.
Yishay
Y
Salem
Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Ramat Gan 52621, Israel; Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv 6997801, Israel.
Yair
Y
Anikster
Department of Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
Friedhelm
F
Hildebrandt
Center for Human Disease Modeling, Duke University Medical Center, Durham, NC 27701, USA. Electronic address: katsanis@cellbio.duke.edu.
Nicholas
N
Katsanis
Monique and Jacques Roboh Department of Genetic Research, Hadassah Medical Center, Jerusalem 91120, Israel. Electronic address: elpeleg@hadassah.org.il.
Orly
O
Elpeleg
Center for Human Disease Modeling, Duke University Medical Center, Durham, NC 27701, USA.
Erica E
EE
Davis
D000015:Abnormalities, Multiple / Q000235:genetics*; D059347:Cardio-Renal Syndrome / Q000235:genetics*; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D065886:Neurodevelopmental Disorders / Q000235:genetics*; D010375:Pedigree; D017354:Point Mutation; D020033:Protein Isoforms / Q000235:genetics
D008565:Membrane Proteins; D020033:Protein Isoforms; C000590663:transmembrane protein 260, human
neurodevelopmental syndrome; splice isoforms; whole-exome sequencing