Knockout mouse models as a resource for the study of rare diseases

Abstract

Rare diseases (RDs) are a challenge for medicine due to their heterogeneous clinical manifestations and low prevalence. There is a lack of specific treatments and only a few hundred of the approximately 7,000 RDs have an approved regime. Rapid technological development in genome sequencing enables the mass identification of potential candidates that in their mutated form could trigger diseases but are often not confirmed to be causal. Knockout (KO) mouse models are essential to understand the causality of genes by allowing highly standardized research into the pathogenesis of diseases. The German Mouse Clinic (GMC) is one of the pioneers in mouse research and successfully uses (preclinical) data obtained from single-gene KO mutants for research into monogenic RDs. As part of the International Mouse Phenotyping Consortium (IMPC) and INFRAFRONTIER, the pan-European consortium for modeling human diseases, the GMC expands these preclinical data toward global collaborative approaches with researchers, clinicians, and patient groups.Here, we highlight proprietary genes that when deleted mimic clinical phenotypes associated with known RD targets (Nacc1, Bach2, Klotho alpha). We focus on recognized RD genes with no pre-existing KO mouse models (Kansl1l, Acsf3, Pcdhgb2, Rabgap1, Cox7a2) which highlight novel phenotypes capable of optimizing clinical diagnosis. In addition, we present genes with intriguing phenotypic data (Zdhhc5, Wsb2) that are not presently associated with known human RDs.This report provides comprehensive evidence for genes that when deleted cause differences in the KO mouse across multiple organs, providing a huge translational potential for further understanding monogenic RDs and their clinical spectrum. Genetic KO studies in mice are valuable to further explore the underlying physiological mechanisms and their overall therapeutic potential.

Fig. 1

Representative high-throughput phenotyping findings from the GMC for selected KO mouse models. Panel A and B: X-ray image analysis shows a decrease in the number of lumbar vertebrae in Nacc1 KO (B) in comparison with WT (A) mice. The phenotype was present in 3/3 female and 5/5 male mutants analyzed. Panel C and D: Optical coherence tomography with optic disc (OD) cupping, fewer blood vessel and OD alteration in Bach2 KO (D) mice and normal OD in WT (C). Panel E, F and G: Microphotographs of Von Kossa-stained trachea (E) and haematoxylin and eosin-stained kidney (F) and glandular stomach (G) sections illustrate the marked tissue calcification in Klotho alpha KO mice. Panel H and I: Transthoracic echocardiograms (short-axis, m-mode) depict decreased left ventricular internal diameter (LVID) in diastole (d, red) and systole (s, green) in Kansl1l KO (I) compared to WT mice (H). Panel J and K: Microphotographs of Luxol Fast Blue-stained coronal brain sections show the reduced thickness of the corpus callosum (*) in Rabgap1 KO mice (K) compared to WT (J). Panel L and M: Optical coherence tomography show fewer blood vessel development and reduced retinal thickness in Rabgap1 KO mice (M) compared to WT (L). Panel N and O: Optical coherence tomography show reduced number of fundic main blood vessels and reduced total retinal thickness in Wsb2 KO mice (O) compared to WT mice (N). All WT were of C57BL/6N background

Fig. 2

Representative high-throughput phenotyping findings from the GMC for Zdhhc5 KO mouse model. Panel A-D: Macrophotographs (A and B) and micro computed tomography (C and D) imaging analyses show short snout and nasal bones (indicated with red arrow) with abnormal growth in Zdhhc5 KO (B and D) in comparison with WT (A and C) mice. Panel E and F: Optical coherence tomography shows reduced retinal thickness in Zdhhc5 KO (F) compared to WT mice (E). Panel G and H: Microphotographs of haematoxylin and eosin-stained testis show degenerative changes with vacuolated seminiferous tubules and multinucleated giant cells (black arrows) in Zdhhc5 KO (H) compared to WT mice (G). All WT were of C57BL/6N background