Cerebellar hypoplasia associated with Arnold-Chiari malformation in a Japanese shorthorn calf

Complex neural tube and skeletal malformations, resembling Chiari malformations, in two calves

Two 1-day-old full-term female calves from different farms located in the Brazilian state of Rio Grande do Sul were unable to stand due to paresis of the pelvic limbs. Both calves had spina bifida on the spinal lumbar segment and were submitted to euthanasia due to poor prognosis. Postmortem examination revealed cerebellar herniation, caudal displacement of the brainstem, rostral deviation of the cranial nerves, caudal extension of occipital lobes, absence of dorsal lamina of lumbar vertebrae with exposed spinal cord, myelodysplasia, kyphosis, segmental spinal agenesis, renal fusion, muscular atrophy, and arthrogryposis. Histology highlighted myelodysplasia (syringomyelia and diplomyelia) and muscular atrophy. The reverse transcription-polymerase chain reactions for ruminant pestivirus were negative. Based on these lesions, the diagnosis of complex neural tube and skeletal malformations was made. A review of previous publications on calves diagnosed with these malformations, originally called Chiari or Arnold-Chiari malformations, revealed a wide range of nervous system and skeletal lesions. These variations amplified the uncertainty regarding whether all cases represent the same disorder and reinforced the importance of reconfiguring the terminology.

Congenital syndromic Chiari-like malformation (CSCM) in Holstein cattle: towards unravelling of possible genetic causes

BACKGROUND

Chiari malformation type II (CMII) was originally reported in humans as a rare disorder characterized by the downward herniation of the hindbrain and towering cerebellum. The congenital brain malformation is usually accompanied by spina bifida, a congenital spinal anomaly resulting from incomplete closure of the dorsal aspect of the spinal neural tube, and occasionally by other lesions. A similar disorder has been reported in several animal species, including cattle, particularly as a congenital syndrome. A cause of congenital syndromic Chiari-like malformation (CSCM) in cattle has not been reported to date. We collected a series of 14 CSCM-affected Holstein calves (13 purebred, one Red Danish Dairy F1 cross) and performed whole-genome sequencing (WGS). WGS was performed on 33 cattle, including eight cases with parents (trio-based; group 1), three cases with one parent (group 2), and three single cases (solo-based; group 3).

RESULTS

Sequencing-based genome-wide association study of the 13 Holstein calves with CSCM and 166 controls revealed no significantly associated genome region. Assuming a single Holstein breed-specific recessive allele, no region of shared homozygosity was detected suggesting heterogeneity. Subsequent filtering for protein-changing variants that were only homozygous in the genomes of the individual cases allowed the identification of two missense variants affecting different genes, SHC4 in case 4 in group 1 and WDR45B in case 13 in group 3. Furthermore, these two variants were only observed in Holstein cattle when querying WGS data of > 5,100 animals. Alternatively, potential de novo mutational events were assessed in each case. Filtering for heterozygous private protein-changing variants identified one DYNC1H1 frameshift variant as a candidate causal dominant acting allele in case 12 in group 3. Finally, the presence of larger structural DNA variants and chromosomal abnormalities was investigated in all cases. Depth of coverage analysis revealed two different partial monosomies of chromosome 2 segments in cases 1 and 7 in group 1 and a trisomy of chromosome 12 in the WDR45B homozygous case 13 in group 3.

CONCLUSIONS

This study presents for the first time a detailed genomic evaluation of CSCM in Holstein cattle and suggests an unexpected genetic and allelic heterogeneity considering the mode of inheritance, as well as the type of variant. For the first time, we propose candidate causal variants that may explain bovine CSCM in a certain proportion of affected calves. We present cattle as a large animal model for human CMII and propose new genes and genomic variants as possible causes for related diseases in both animals and humans.

Arnold Chiari malformation classified as Chiari 1.5 malformation in a Japanese black calf

A 2-day-old male black calf presented with neurological symptoms, including opisthotonus. It was unable to stand due to hindquarter paresis. At 5 days old, the calf was able to stand, but exhibited a crossed forelimb gait. Computed tomography and magnetic resonance imaging revealed the expansion of the sutures between the squamous-lateral part of the occipital bone and between the occipital-temporal bone, cerebellar tonsillar herniation, posterior displacement of the brainstem, and cervical syringomyelia at 12 days old. This is the first case report of a live calf diagnosed with Arnold Chiari malformation classified as Chiari type 1.5 malformation in humans.

First occurrence of Arnold Chiari type II malformation and associated abnormalities in a Gir calf produced in vitro from Brazil - case report

ABSTRACT This study characterized the clinical, radiological, ultrasound, and necroscopic findings of a case of Arnold-Chiari type II malformation in a Gir breed calf from Brazil. The animal was hospitalized at sixty days of age, in permanent sternal recumbency, cutaneous appendix at the 4th lumbar vertebra and kyphoscoliosis of the caudal and lumbosacral thoracic spine. Radiographic examination of the spine and skull revealed spina bifida and suspected occipital hypoplasia. Upon examination of myelography with an injection of lumbar and atlantooccipital contrast, it was possible to visualize the meningocele at the 4th lumbar vertebra region and findings at the rhombencephalon level of increased regional pressure with failure to fill the contrast in the posterior fossa, in the presence of clear demarcation of the circumvolutions of the cerebral cortex and the subarachnoid space of the cervical spinal cord. Ultrasonographic examination of the cerebellum showed an insinuation of the cerebellar worm through the foramen magnum. The animal did not show changes in complete blood count, biochemical series, and cerebrospinal fluid and was negative for Pestivirus. There was a worsening of the clinical conditions and the animal died. This malformation of unknown etiology must be studied as a differential diagnosis of the nervous system disorders.

Cerebellar Disease of Ruminants

Cerebellar disease can be congenital or acquired. Clinical signs of cerebellar disease include hypermetric gait in all limbs, normal to increased muscle tone, wide-based stance, swaying, intention tremor, and convulsions. Vestibular signs may be observed. Differential diagnoses for etiology include congenital (hypoplasia, abiotrophy, and lysosomal storage diseases), viral, bacterial, and toxic plants. Animals may present aborted as fetuses or stillborn, be affected at birth, develop disease at a few months old, or acquire the disease later in life.

Dicephalus, Arnold-Chiari malformation and spina bifida in a Japanese black calf

A case of dicephalus, Arnold-Chiari malformation (ACM) and spina bifida was reported in a Japanese Black calf. Both brains and crania showed the same abnormalities as those of the monocephalic cases with ACM and were mirror-images of each other. The common findings were elongation of the brain, caudal displacement and hypoplasia of the cerebellum, dorso-ventral compression of the skull, platybasia, and enlargement of the foramen magnum. The craniolacunia was also found in our case.