ESPN 50th Annual Meeting

ESPN 2017


 
Mutations in the leukemia inhibitory factor receptor (LIFR) gene and Lifr deficiency cause urinary tract malformations
HAFFNER DIETER 1 KOSFELD ANNE 2 BRAND FRANK 2 WEISS ANNA-CARINA 3 KREUZER MARTIN 1 GOERK MICHAELA 4 SCHUBERT STEPHANIE 2 MARTENS JÖRN HELGE 2 SCHUBERT STEPHANIE 2 SCHäFER ANNE-KATHRIN 3 RIEHMER VERA 2 BRäSEN JAN HINRICH 6 Hennies Imke 1 PAPE LARS 1 AMANN KERSTIN 4 KROGVOLD LARS 5 Bjerre Anna Kristina 5 Daniel Christoph 4 Kispert Andreas 3 Weber Ruthild Gisela 2

1- DEPARTMENT OF PEDIATRIC KIDNEY, LIVER AND METABOLIC DISEASES, HANNOVER MEDICAL SCHOOL, HANNOVER, GERMANY
2- DEPARTMENT OF HUMAN GENETICS, HANNOVER MEDICAL SCHOOL, HANNOVER, GERMANY
3- INSTITUTE OF MOLECULAR BIOLOGY, HANNOVER MEDICAL SCHOOL, HANNOVER, GERMANY
4- DEPARTMENT OF NEPHROPATHOLOGY, FRIEDRICH-ALEXANDER UNIVERSITY OF ERLANGEN-NÜRNBERG, ERLANGEN, GERMANY
5- DIVISION OF PAEDIATRIC AND ADOLESCENT MEDICINE, OSLO UNIVERSITY HOSPITAL, OSLO, NORWAY
6- Department of Pathology, Hannover Medical School, Hannover, Germany
 
Introduction:

Congenital anomalies of the kidneys and urinary tract (CAKUT) are the most common cause of chronic kidney disease in children. As CAKUT is a genetically heterogeneous disorder and most cases are genetically unexplained, we aimed to identify new CAKUT causing genes. 

Material and methods:

Whole-exome sequencing (WES) and a trio-based de novo strategy were performed in a sporadic CAKUT patient and his healthy parents identifying the leukemia inhibitory factor receptor (LIFRas a novel CAKUT candidate gene. Additionally, LIFR mutational screening of a CAKUT patient cohort as well as in vitro and in vivo characterization of this gene or identified variants thereof were performed in cellular and mouse models.

 

Results:

WES identified a novel heterozygous de novo frameshift variant in the LIFR gene causing instability of the mRNA in a patient presenting with bilateral CAKUT and requiring kidney transplantation at one year of age. LIFR encodes a transmembrane receptor utilized by IL-6 family cytokines, mainly by the leukemia inhibitory factor (LIF). Mutational analysis of 121 further patients with severe CAKUT yielded two rare heterozygous LIFR missense variants predicted to be pathogenic in three unrelated patients. LIFR mutants showed decreased half-life and cell membrane localization resulting in reduced LIF-stimulated STAT3 phosphorylation. LIFR showed high expression in human fetal kidney and the human ureter, and was also expressed in the developing murine urogenital system. Lifr knockout mice displayed urinary tract malformations including hydronephrosis, hydroureter, ureter ectopia, and, consistently, reduced ureteral lumen and muscular hypertrophy, similar to the phenotypes observed in patients carrying LIFR variants. Additionally, a form of cryptorchidism was detected in all Lifr-/- mice and the patient carrying the LIFR frameshift mutation. 

Conclusions:

We demonstrate heterozygous novel or rare LIFR mutations in 3.3% of CAKUT patients, and provide evidence that Lifr deficiency and deactivating LIFR mutations cause highly similar anomalies of the urogenital tract in mice and humans.