Extraordinary incidence of cervical ribs indicates vulnerable condition in Late Pleistocene mammoths

Reumer, J.W.F.; Broek, Clara M. A. ten; Galis, Frietson

doi:10.7287/peerj.preprints.263v1

Cited by 2 publications

(2 citation statements)

References 19 publications

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“…33% in mammoths before extinction (Reumer et al. ), 11% in minipigs (Kd, ) or 7.5% in humans (Palma & Carini, )]. Pedigrees were not available for analysis in any of the dogs included in this study; and therefore, the mode of inheritance or the degree of inbreeding could not be studied.…”

Section: Discussionmentioning

confidence: 99%

C7 vertebra homeotic transformation in domestic dogs – are Pug dogs breaking mammalian evolutionary constraints?

et al. 2018

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The number of cervical vertebrae in mammals is almost constant at seven, regardless of their neck length, implying that there is selection against variation in this number. Homebox (Hox) genes are involved in this evolutionary mammalian conservation, and homeotic transformation of cervical into thoracic vertebrae (cervical ribs) is a common phenotypic abnormality when Hox gene expression is altered. This relatively benign phenotypic change can be associated with fatal traits in humans. Mutations in genes upstream of Hox, inbreeding and stressors during organogenesis can also cause cervical ribs. The aim of this study was to describe the prevalence of cervical ribs in a large group of domestic dogs of different breeds, and explore a possible relation with other congenital vertebral malformations (CVMs) in the breed with the highest prevalence of cervical ribs. By phenotyping we hoped to give clues as to the underlying genetic causes. Twenty computed tomography studies from at least two breeds belonging to each of the nine groups recognized by the Federation Cynologique Internationale, including all the brachycephalic 'screw-tailed' breeds that are known to be overrepresented for CVMs, were reviewed. The Pug dog was more affected by cervical ribs than any other breed (46%; P < 0.001), and was selected for further analysis. No association was found between the presence of cervical ribs and vertebral body formation defect, bifid spinous process, caudal articular process hypoplasia/aplasia and an abnormal sacrum, which may infer they have a different aetiopathogenesis. However, Pug dogs with cervical ribs were more likely to have a transitional thoraco-lumbar vertebra (P = 0.041) and a pre-sacral vertebral count of 26 (P < 0.001). Higher C7/T1 dorsal spinous processes ratios were associated with the presence of cervical ribs (P < 0.001), supporting this is a true homeotic transformation. Relaxation of the stabilizing selection has likely occurred, and the Pug dog appears to be a good naturally occurring model to further investigate the aetiology of cervical ribs, other congenital vertebral anomalies and numerical alterations.

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Section: Discussionmentioning

confidence: 99%

C7 vertebra homeotic transformation in domestic dogs – are Pug dogs breaking mammalian evolutionary constraints?

et al. 2018

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“…This hypothesis is further supported by the higher prevalence of cervical ribs in individuals with adverse outcomes. Several studies showed a high frequency of (rudimentary) cervical ribs in specific study populations [8], such as stillbirths and deceased neonates with and without structural anomalies [4], children suffering from malignancies [9] and extinct mammoths [10].…”

Section: Introductionmentioning

confidence: 99%

Increased prevalence of abnormal vertebral patterning in fetuses and neonates with trisomy 21

Schut

Broek

Cohen–Overbeek

et al. 2018

The Journal of Maternal-Fetal & Neonatal Medicine

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Purpose: To assess the prevalence of an abnormal number of ribs in a cohort of fetuses and neonates with trisomy 21 and compare this with a subgroup of fetuses without anomalies. Materials and methods: Radiographs of 67 deceased fetuses, neonates, and infants that were diagnosed with trisomy 21 were reviewed. Terminations of pregnancy were included. The control group was composed of 107 deceased fetuses, neonates, and infants without known chromosomal abnormalities, structural malformations, infections or placental pathology. Cases in which the number of thoracic ribs or presence of cervical ribs could not be reliably assessed were excluded. The literature concerning vertebral patterning in trisomy 21 cases and healthy subjects was reviewed. Results: Absent or rudimentary 12th thoracic ribs were found in 26/54 (48.1%) cases with trisomy 21 and cervical ribs were present in 27/47 (57.4%) cases. This prevalence was significantly higher compared to controls (28/100, 28.0%, X 2 (1) ¼ 6.252, p ¼ .012 and 28/97, 28.9%, X 2 (1) ¼ 10.955, p < .001, respectively). Conclusions: Rudimentary or absent 12th thoracic ribs and cervical ribs are significantly more prevalent in deceased fetuses and infants with trisomy 21. ARTICLE HISTORY

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Extraordinary incidence of cervical ribs indicates vulnerable condition in Late Pleistocene mammoths

Cited by 2 publications

References 19 publications

C7 vertebra homeotic transformation in domestic dogs – are Pug dogs breaking mammalian evolutionary constraints?

C7 vertebra homeotic transformation in domestic dogs – are Pug dogs breaking mammalian evolutionary constraints?

Increased prevalence of abnormal vertebral patterning in fetuses and neonates with trisomy 21

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