Cardiomyopathy associated 5 (CMYA5) implicated as a genetic risk factor for radial hemimelia in Siamese cats.

OBJECTIVES: The present study aimed to determine the inheritance pattern and genetic cause of congenital radial hemimelia (RH) in cats. METHODS: Clinical and genetic analyses were conducted on a Siamese cat family (n = 18), including two siblings with RH. Radiographs were obtained for the affected kittens and echocardiograms of an affected kitten and sire. Whole genome sequencing was completed on the two cases and the parents. Genomic data were compared with the 99 Lives Cat Genome data set of 420 additional domestic cats with whole genome and whole exome sequencing data. Variants were considered as homozygous in the two cases of the siblings with RH and heterozygous in the parents. Candidate variants were genotyped by Sanger sequencing in the extended pedigree. RESULTS: Radiographs of the female kitten revealed bilateral absence of the radii and bowing of the humeri, while the male kitten showed a dysplastic right radius. Echocardiography suggested the female kitten had restrictive cardiomyopathy with a positive left atrial-to-aortic root ratio (LA:Ao = 1.83 cm), whereas hypertrophic cardiomyopathy was more likely in the sire, showing diastolic dysfunction using tissue Doppler imaging (59.06 cm/s). Twenty-two DNA variants were unique and homozygous in the affected kittens and heterozygous in the parents. Seven variants clustered in one chromosomal region, including two frameshift variants in cardiomyopathy associated 5 (CMYA5) and five variants in junction mediating and regulatory protein, P53 cofactor (JMY ), including a missense and an in-frame deletion. CONCLUSIONS AND RELEVANCE: The present study suggested an autosomal recessive mode of inheritance with variable expression for RH in the Siamese cat family. Candidate variants for the phenotype were identified, implicating their roles in bone development. These genes should be considered as potentially causal for other cats with RH. Siamese cat breeders should consider genetically testing their cats for these variants to prevent further dissemination of the suspected variants within the breed.

Bilateral radial hemimelia and multiple malformations in a kitten.

Hemimelia is a congenital disease of complete or partial absence of one or more bones. The most important hypothesis is that radial agenesis is a consequence of neural crest injury. Treatment selection depends on the degree of the deformity and the reduction of limb function. This report describes a case of bilateral radial hemimelia and multiple malformations in a kitten aged 2 months treated conservatively with splint bandage, until bone maturity. The re-evaluation was performed 4 years later.

Two cases of feline ectromelia: autopodium ectromelia associated with humero-ulnar synostosis and zeugopodium ectromelia.

Congenital limb deformities are rarely reported in cats. This paper describes the radiographic findings of congenital forelimb malformations in two cats. The radiographic changes were suggestive of an autopodium ectromelia associated with humero-ulnar synostosis in one case and zeugopodium ectromelia in the other case. Congenital feline limb deformities are poorly documented and, to the authors' knowledge, this is the first time that humero-ulnar synostosis has been reported in cats.

Chromosome instability in a calf with amelia of thoracic limbs.

We report here on a case of a Holstein-Friesian male calf with the congenital total absence of thoracic limbs (amelia). Cytogenetic study showed a high rate of chromosome instability, represented by chromosome or chromatid breaks and gaps in 46% of the analyzed metaphase spreads. Moreover, 12% of the spreads appeared to be polypolid. The number of micronuclei also was significantly higher when compared to control animals. This paper discusses the association between chromosome instability and limb malformation.

Amelia anterior esquerda incompleta em potro. Descriçäo de um caso / Incomplete anterior left amelia in a fool. A case report

Descreve-se um caso de amelia anterior em um potro da raça Mangalarga Marchador, nascido de parto eutócico e sacrificado 40 dias após. O estudo cromossômico do potro, da égua e do garanhäo revelou cariótipo normal

Skeletal morphogenesis: comparative effects of a mutant gene and a teratogen.

As a teratogenic agent retinoic acid (RA) produces severe limb reduction defects if administered at a certain stage of embryonic development. In vitro, RA is able to prevent chondrogenesis and this inhibitory effect is accompanied by the absence of cartilage specific proteoglycans in treated cultures. Such an effect is ruled out as a direct causative factor in teratogenesis for two reasons. First, the limbs of treated embryos show extensive chondrogenesis and this cartilage is normal as far as the expression of biochemical markers of differentiation are concerned. Second, the morphogenetic effects of a mutant gene, cmd, where there is a functional deficit of the proteoglycan core protein are very different from those associated with RA-induced teratogenesis. The differences between the two are not wholly reconciled by the fact that the effects of the mutant gene are cumulative and progressive while those of the RA insult are transitory. There are a number of developmental events which are, however, altered by RA in the mesenchymal cells of the early limb bud such as cell proliferation, cell death, and hyaluronic acid metabolism. Not only any one or more of these factors may secondarily inhibit chondrogenesis but, more importantly, may also have a number of other consequences in the developing embryo. Since a number of cell types besides mesenchymal cells respond to RA by altering their pattern of differentiation, it is conceivable that some fundamental molecular step in the process of differentiation provides a target for its action. In a recent review, Sporn and Roberts (1983) have suggested that to be compatible with the wide ranging effects of retinoids documented so far, any hypothesis put forward for its molecular mechanism of action must include a role in gene expression. No experimental work has yet directly addressed how retinoids might modify gene expression. We believe that along with teratocarcinoma stem cell lines, the use of retinoids as selective teratogens may open up another avenue in search of molecular mechanisms of cell differentiation.