Peer-reviewed veterinary case report
Kitten with vitamin D rickets linked to new gene mutation
By Habacher, Gabriele et al.·Published in Journal of feline medicine and surgery·2023·Raddenstiles Veterinary Surgery, United Kingdom·View original on PubMed →
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Original publication title: Feline precision medicine using whole-exome sequencing identifies a novel frameshift mutation for vitamin D-dependent rickets type 2.
- Species:
- cat
Plain-English summary
A 14-week-old female domestic longhair kitten was brought to the vet because she was limping and was much smaller than her littermate. Tests showed she had low calcium levels and signs of rickets, a bone disease caused by vitamin D deficiency. The vet treated her with pain relief, high doses of vitamin D, and calcium supplements, which helped her calcium levels return to normal and supported her growth, although some bone issues remained. Genetic testing revealed a unique mutation affecting her vitamin D receptor, which likely caused her condition.
People also search for: kitten limping · rickets in cats · vitamin D deficiency treatment for kittens
Abstract
OBJECTIVES: A 14-week-old female domestic longhair kitten presented with shifting lameness and disproportionately smaller size compared with a co-housed littermate. METHODS: Hematology and serum biochemical testing were conducted to investigate causes for delayed growth, and radiographs of the appendicular skeleton were obtained. RESULTS: The afflicted kitten had marked hypocalcemia, mild hypophosphatemia and substantial elevations in alkaline phosphatase activity, as well as pathognomonic radiographic findings consistent with rickets. Skeletal changes and hypocalcemia prompted testing of concentrations of parathyroid hormone (PTH) and vitamin D metabolites. Endocrine testing demonstrated significant increases in serum concentrations of PTH and 1,25-dihydroxycholecalciferol (calcitriol), supporting a diagnosis of vitamin D-dependent rickets type 2. Provision of analgesia, supraphysiologic doses of calcitriol and calcium carbonate supplementation achieved normalization of the serum calcium concentration and restoration of normal growth, although some skeletal abnormalities persisted. Once skeletally mature, ongoing calcitriol supplementation was not required. Whole-exome sequencing (WES) was conducted to identify the underlying DNA variant. A cytosine deletion at cat chromosome position B4:76777621 in VDR (ENSFCAT00000029466:c.106delC) was identified and predicted to cause a stop codon in exon 2 (p.Arg36Glufs*18), disrupting >90% of the receptor. The variant was unique and homozygous in this patient and absent in the sibling and approximately 400 other cats for which whole-genome and whole-exome data were available. CONCLUSIONS AND RELEVANCE: A unique, heritable form of rickets was diagnosed in a domestic longhair cat. WES identified a novel frameshift mutation affecting the gene coding for the vitamin D3 receptor, determining the likely causal genetic variant. Precision medicine techniques, including whole-exome and whole-genome sequencing, can be a standard of care in cats to identify disease etiologies, and to target therapeutics and personalize treatment.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/37387221/