Allelic Mutations of KITLG, Encoding KIT Ligand, Cause Asymmetric and Unilateral Hearing Loss and Waardenburg Syndrome Type 2.

TitleAllelic Mutations of KITLG, Encoding KIT Ligand, Cause Asymmetric and Unilateral Hearing Loss and Waardenburg Syndrome Type 2.
Publication TypeJournal Article
Year of Publication2015
AuthorsSeco, CZazo, de Castro, LSerrão, van Nierop, JW, Morín, M, Jhangiani, S, Verver, EJJ, Schraders, M, Maiwald, N, Wesdorp, M, Venselaar, H, Spruijt, L, Oostrik, J, Schoots, J, van Reeuwijk, J, Lelieveld, SH, Huygen, PLM, Insenser, M, Admiraal, RJC, Pennings, RJE, Hoefsloot, LH, Arias-Vásquez, A, de Ligt, J, Yntema, HG, Jansen, JH, Muzny, DM, Huls, G, van Rossum, MM, Lupski, JR, Moreno-Pelayo, MAngel, Kunst, HPM, Kremer, H
Corporate AuthorsBaylor-Hopkins Center for Mendelian Genomics
JournalAm J Hum Genet
Date Published2015 Nov 05
KeywordsAlleles, Animals, Female, Fluorescent Antibody Technique, Genetic Linkage, Hearing Loss, Unilateral, Humans, Male, Mice, Mutation, NIH 3T3 Cells, Pedigree, Phenotype, Prognosis, Real-Time Polymerase Chain Reaction, Reverse Transcriptase Polymerase Chain Reaction, RNA, Messenger, Stem Cell Factor, Waardenburg Syndrome

Linkage analysis combined with whole-exome sequencing in a large family with congenital and stable non-syndromic unilateral and asymmetric hearing loss (NS-UHL/AHL) revealed a heterozygous truncating mutation, c.286_303delinsT (p.Ser96Ter), in KITLG. This mutation co-segregated with NS-UHL/AHL as a dominant trait with reduced penetrance. By screening a panel of probands with NS-UHL/AHL, we found an additional mutation, c.200_202del (p.His67_Cys68delinsArg). In vitro studies revealed that the p.His67_Cys68delinsArg transmembrane isoform of KITLG is not detectable at the cell membrane, supporting pathogenicity. KITLG encodes a ligand for the KIT receptor. Also, KITLG-KIT signaling and MITF are suggested to mutually interact in melanocyte development. Because mutations in MITF are causative of Waardenburg syndrome type 2 (WS2), we screened KITLG in suspected WS2-affected probands. A heterozygous missense mutation, c.310C>G (p.Leu104Val), that segregated with WS2 was identified in a small family. In vitro studies revealed that the p.Leu104Val transmembrane isoform of KITLG is located at the cell membrane, as is wild-type KITLG. However, in culture media of transfected cells, the p.Leu104Val soluble isoform of KITLG was reduced, and no soluble p.His67_Cys68delinsArg and p.Ser96Ter KITLG could be detected. These data suggest that mutations in KITLG associated with NS-UHL/AHL have a loss-of-function effect. We speculate that the mechanism of the mutation underlying WS2 and leading to membrane incorporation and reduced secretion of KITLG occurs via a dominant-negative or gain-of-function effect. Our study unveils different phenotypes associated with KITLG, previously associated with pigmentation abnormalities, and will thereby improve the genetic counseling given to individuals with KITLG variants.

Alternate JournalAm J Hum Genet
PubMed ID26522471
PubMed Central IDPMC4667106
Grant ListU54 HG006542 / HG / NHGRI NIH HHS / United States
UM1 HG006542 / HG / NHGRI NIH HHS / United States
HG006542 / HG / NHGRI NIH HHS / United States

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