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Affected cats have marked microcephaly with polymicrogyria. Images of whole brain from (A) adult unaffected (+/+), and (B) adult and (C) juvenile affected (-/-) cats. Affected cats have dramatically decreased cerebral cortex size with normal formation of the cerebellum. (D) Brain weights of affected cats are significantly decreased with or without normalization to body weight, which is similar to unaffected cats. (E) Representative sections (left image, normal; right image, affected) from the region of the parietal cortex have gyrification defects characterized by shallow sulci and fusion of small gyri consistent with polymicrogyria, as well as abnormal white matter of the corona radiata and internal capsule. https://doi.org/10.1371/journal.pgen.1008671.g001
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Cerebral cortical size and organization are critical features of neurodevelopment and human evolution, for which genetic investigation in model organisms can provide insight into developmental mechanisms and the causes of cerebral malformations. However, some abnormalities in cerebral cortical proliferation and folding are challenging to study in l...
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... together, these findings suggest that affected adult cats had a stable, non-progressive neurologic disease. At necropsy, affected juvenile and adult cats exhibited generalized microcephaly and polymicrogyria with focal lissencephaly and regional gyral variability (Fig 1A-1C). The most severely affected areas (frontoparietal) often had a cobblestone appearance. ...
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... most severely affected areas (frontoparietal) often had a cobblestone appearance. The average brain weight of affected cats was 4.3 grams per kilogram of body weight, while for unaffected and carrier cats average brain weight was 7.8 grams per kilogram, indicating a 45% decrease in brain mass (Fig 1D). In contrast to the significant abnormalities in the cerebral cortex, the size and structure of the cerebellum was normal with no vermal or hemispheric hypoplasia, dysplasia or agenesis. ...
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... from affected cats aged 1-8 months were evaluated histologically in comparison to aged-matched controls (Fig 1E). Overall, affected cats exhibited variable thinning of the cerebral cortex, especially in dorsal and lateral regions, and disorganization of cortical layers. ...
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... confirm and further fine-map the region, we carried out amplicon-based genotype-bysequencing on an additional 91 cats (Fig 3, S1 Table), using 26 variants across an ~70 Mb interval that contains the candidate region on chromosome F1, 4 additional variants that span the remainder of chromosome F1, and 20 variants from other chromosomes. All affected cats, but no unaffected cats, were homozygous for a 1.3 Mb haplotype on chromosome F1 (Fig 3B) in which the peak LOD score was 10.1 ( Fig 3C, S3 Table); all variants on chromosomes other than F1 exhibited LOD scores < 1.8 (S3 Table), and the variants used for initial zygosity filtering criteria are presented in S4 Table. ...
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... treatment with TNFα, fibroblasts from affected animals exhibited reduced cell viability ( Fig 9A) and increased caspase-8 activity (Fig 10B). Cell viability and caspase 8 activity did not change in the absence of TNFα treatment in fibroblasts from affected or unaffected animals. ...
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... viability and caspase 8 activity did not change in the absence of TNFα treatment in fibroblasts from affected or unaffected animals. Exposure to FGFb for 72 hours yielded an ~ 2.5-fold increase in cell number in fibroblasts from unaffected animals, significantly elevated (p = 0.02) to ~3.5-fold in fibroblasts from affected animals (Fig 10C). Taken together, these results confirm that the effects of PEA15 on apoptosis and cell proliferation are similar in cats and mice, and illustrate the functional impact of the PEA15 pathogenic variant in cats with cerebral dysgenesis. ...
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... propose a neuropathologic mechanism for the abnormalities described here whereby PEA15 normally serves to negatively regulate neuronal apoptosis and astrocyte proliferation (Fig 11, left), as has been demonstrated previously in mice. In the absence of PEA15, increased neuronal apoptosis and astrocyte proliferation leads to the production of excessive ...
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... mutation and lissencephaly in the domestic cat perineuronal nets, axonal disorganization and underdeveloped white matter tracts (Fig 11, right). Additional studies of PEA15-deficient cats should help determine at which phase of cortical development-neuroepithelial stem cell proliferation, neuronal stem cell migration, or synaptogenesis, apoptosis, and synaptic pruning-the postulated mechanisms are operative. ...
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... RNA was extracted from the grey matter of the cerebral cortex of 16 cats (seven affected cats, five obligate carriers based on breeding records, S1 Fig, S1 Table, and four unaffected animals from a different pedigree that did not segregate the cerebral dysgenesis pathogenic variant) using the Qiagen RNeasy Lipid Tissue Mini Kit according to the manufacturer's instructions. Ages ranged from four months to six years for affected cats, 2-12 years for obligate carriers, and 2-5.5 years for unaffected cats. ...
Citations
... The feline brain, in contrast with the lissencephalic mouse brain, is gyrencephalic (Zilles et al., 2013); this trait favors comparisons both with primates, as well as with the stem mammalian ancestor (Kelava et al., 2013;Catania, 2017). Additionally, felids can be regarded as an organism that provides a "bridge" between rodents and primates (Bradbury et al., 2013;Stolzberg et al., 2017); thus the study of the development of the feline brain not only can provide novel insights into the evolution of the mammalian brain but can also be useful for basic and translational neuroscience (e.g., in Graff et al., 2020). ...
... These results, along with the fact that the feline brain is gyrencephalic, suggest that cats can provide a useful animal model in the study of the brain in ontogenesis and evolution. To our knowledge, this is the first systematic analysis of the feline telencephalon genoarchitecture and we hope that it will provide a reference for future research, especially given the re-appearance of this species in neuroscience research (Hinova-Palova et al., 2019;Valdés-Cruz et al., 2019;Graff et al., 2020). ...
The telencephalon develops from the alar plate of the secondary prosencephalon and is subdivided into two distinct divisions, the pallium, which derives solely from prosomere hp1, and the subpallium which derives from both hp1 and hp2 prosomeres. In this first systematic analysis of the feline telencephalon genoarchitecture, we apply the prosomeric model to compare the expression of a battery of genes, including Tbr1, Tbr2, Pax6, Mash1, Dlx2, Nkx2-1, Lhx6, Lhx7, Lhx2 , and Emx1 , the orthologs of which alone or in combination, demarcate molecularly distinct territories in other species. We characterize, within the pallium and the subpallium, domains and subdomains topologically equivalent to those previously described in other vertebrate species and we show that the overall genoarchitectural map of the E26/27 feline brain is highly similar to that of the E13.5/E14 mouse. In addition, using the same approach at the earlier (E22/23 and E24/25) or later (E28/29 and E34/35) stages we further analyze neurogenesis, define the timing and duration of several developmental events, and compare our data with those from similar mouse studies; our results point to a complex pattern of heterochronies and show that, compared with the mouse, developmental events in the feline telencephalon span over extended periods suggesting that cats may provide a useful animal model to study brain patterning in ontogenesis and evolution.
... Whole genome sequencing (WGS) and whole exome sequencing (WES) are available for domestic cats as genomic diagnostic tools for their healthcare via the community-based 99 Lives Cat Genome Sequencing Consortium [4,5]. Consortium studies are defining new disease variants for well-recognized disease genes, thereby supporting established biomedical models, such as Niemann-Pick disease type C [6]; new variants in new genes for known diseases, such as disproportionate dwarfism, thereby providing new genetic considerations for undiagnosed patients [7]; and new variants for new diseases of conserved biological processes, such as brain development or cell migration and differentiation [8]. The cat's genomic tools and the 99 Lives Consortium have led to more rapid identification of causal disease and trait variants in cats, hence naturally occurring biomedical models, with~84 mutations causing diseases under negative selection and 44 desired variants under positive selection in cats and at least seven variants influencing one blood group (https://omia. ...
Feline genomic medicine can decode human variants of uncertain significance (VUSs). Telomere-to-telomere genome assemblies are feasible for all felid species, supporting genetic evolution and speciation studies. Their highly conserved genomic organization compared to humans suggests cats may also decipher the intergenic variation affecting the 3D chromosome structures influencing gene regulation.
... Khufu also is effective for mapping traits in domestic cats. Graff et al (2020) identified a mutation in PEA15 that leads to impaired cerebral cortical size in domestic cats by analyzing sequence data from a set of affected and unaffected individuals. We analyzed only the WGS data which included 3 obligate carriers and 2 affected cats and RNA-seq data including 7 affected cats and 4 unaffected cats ( Figure S11). ...
Next Generation sequencing was a step change for molecular genetics and genomics. Illumina sequencing in particular still provides substantial value to animal and plant genomics. A simple yet powerful technique, referred to as QTL sequencing (QTL-seq) is susceptible to high levels of noise due to ambiguity of alignment of short reads in complex regions of the genome. This noise is particularly high when working with polyploid and/or outcrossing crop species, which impairs the efficacy of QTL-seq in identifying functional variation. By filtering loci based on the optimal alignment of short reads, we have developed a pipeline, named Khufu, that substantially improves the accuracy of QTL-seq analysis in complex genomes, allowing de novo variant discovery directly from bulk sequence. We first demonstrate the pipeline by identifying and validating loci contributing to blanching percentage in peanut using lines from multiple related populations. Using other published datasets in peanut, Brassica rapa, Hordeum volgare, Lactua satvia, and Felis catus, we demonstrate that Khufu produces more accurate results straight from bulk sequence. Khufu works across species, genome ploidy level, and data types. In cases where identified QTL were fine mapped, the fine mapped region corresponds to the top of the peak identified by Khufu. The accuracy of Khufu allows the analysis of population sequencing at very low coverage (<3x), greatly decreasing the amount of sequence needed to genotype even the most complex genomes.
... En effet, les souris invalidées dans PEA15 ne présentaient pas de phénotype. Le chat a ainsi fourni un nouveau gène candidat pour les lissencéphalies humaines (Graff et al. 2020), comme il avait déjà fourni de nouveaux candidats pour une affection oculaire (Cogné et al. 2020) ou du nanisme (Buckley et al. 2020a). La montée en puissance et les retombées récentes du projet 99 Lives témoignent de l'intérêt du chat en génétique médicale comparée. ...
Le séquençage et l'annotation du génome du chat domestique (Felis catus), initialement publiés en 2007, étaient de médiocre qualité. Ils ont depuis été amendés puis complétés par le développement d'outils de génomique qui, combinés à des stratégies génétiques en constante évolution, permettent de rechercher gènes et variants d'intérêt avec efficacité. Ces progrès bénéficient à la médecine vétérinaire féline, mais font également du chat domestique un modèle pour l'étude de la domestication, l'évolution des espèces, mais aussi un modèle biomédical en constante ascension. Progressivement, le chat qui a déjà conquis le cœur des foyers français et du web mondial, est en train de conquérir le cœur des généticiens.
Microcephaly is a rare neurodevelopmental disorder characterized by reduced skull circumference and brain volume that occurs sporadically in farm animals. We investigated an early‐onset neurodegenerative disorder observed in seven lambs of purebred Kerry Hill sheep. Clinical signs included inability to stand or severe ataxia, convulsions, and early death. Diagnostic imaging and brain necropsy confirmed microcephaly. The pedigree of the lambs suggested monogenic autosomal recessive inheritance. We sequenced the genome of one affected lamb, and comparison with 115 control genomes revealed a single private protein‐changing variant. This frameshift variant, MFSD2A: c.285dupA, p.(Asp96fs*9), represents a 1‐bp duplication predicted to truncate 80% of the open reading frame. MFSD2A is a transmembrane protein that is essential for maintaining blood–brain barrier homeostasis and plays a key role in regulating brain lipogenesis. Human MFSD2A pathogenic variants are associated with a neurodevelopmental disorder with progressive microcephaly, spasticity, and brain imaging abnormalities (NEDMISBA, OMIM 616486). Here we present evidence for the occurrence of a recessively inherited form of microcephaly in sheep due to a loss‐of‐function variant in MFSD2A (OMIA 002371‐9940). To the best of our knowledge, this is the first report of a spontaneous MFSD2A variant in domestic animals.
