Evolutionary Ecology Group, Department of Biology, University of Antwerp, Antwerp, Belgium.
J Anat. 2011 Sep;219(3):403-9. doi: 10.1111/j.1469-7580.2011.01400.x. Epub 2011 Jun 20.
In humans, an increasing body of evidence has linked the frequency of cervical ribs to stillbirths, other malformations and early childhood cancers. However, the frequency of cervical ribs in a putatively healthy fetal population is not sufficiently known to assess the actual medical risks of these prenatal findings. We therefore analyzed the presence of skeletal anomalies in a series of 199 electively aborted fetuses, which were whole-mount stained with alizarin red specific for skeletal tissues. Results show that approximately 40% of the fetuses had cervical ribs, even though external congenital abnormalities such as craniofacial and limb defects were absent. A literature overview indicates that the observed frequency of cervical ribs is comparable to results previously obtained for deceased fetuses with no or minor congenital anomalies, and higher than expected for healthy fetuses. This unexpected result can probably in part be explained by a higher detection rate of small cervical ribs when using alizarin red staining instead of radiographs. Additionally, studies in the literature suggest that the size of a cervical rib may indicate the severity of abnormalities, but this possibility requires further research. Anomalies of the axial skeleton are known to be caused by a disturbance of early development, which alters Hox gene expression, but in this study the origin of the stress could not be verified as maternal medical data were not available. The co-occurrence of rudimentary or absent 12th ribs in 23.6% of the cases with cervical ribs indicates that in approximately 8% of the fetuses a homeotic shift occurred over a larger part of the vertebral column. This suggests that the expression of multiple Hox genes may have been affected in these fetuses. Together, the high incidence of cervical ribs and also their co-occurrence with rudimentary or absent 12th ribs suggests that there may have been a disturbance of early development such that the studied fetuses are probably not informative about the general population. Future studies determining the frequency of cervical ribs in a more healthy fetal population are therefore needed to evaluate their potential as an indicator of medical risks.
在人类中，越来越多的证据将颈肋的频率与死产、其他畸形和儿童早期癌症联系起来。然而，在假定健康的胎儿人群中，颈肋的频率尚不清楚，无法评估这些产前发现的实际医疗风险。因此，我们分析了一系列 199 例选择性流产胎儿的骨骼异常情况，这些胎儿用茜素红特异性染色骨骼组织进行了整体染色。结果表明，大约 40%的胎儿有颈肋，尽管没有外部先天性异常，如颅面和肢体缺陷。文献综述表明，观察到的颈肋频率与先前获得的无或轻微先天性异常的已故胎儿的结果相当，高于健康胎儿的预期。这种意外结果可能部分可以解释为，与使用 X 光片相比，使用茜素红染色可以更准确地检测到较小的颈肋。此外，文献中的研究表明，颈肋的大小可能表明异常的严重程度，但这种可能性需要进一步研究。已知轴向骨骼的异常是由早期发育紊乱引起的，这会改变 Hox 基因的表达，但在本研究中，由于没有获得母体医学数据，因此无法验证应激的起源。在有颈肋的病例中，23.6%同时存在发育不全或缺失的第 12 肋骨，这表明在大约 8%的胎儿中，脊椎发生了同源转换，涉及更大的一部分。这表明这些胎儿的多个 Hox 基因的表达可能受到了影响。总之，颈肋的高发生率以及它们与发育不全或缺失的第 12 肋骨的同时发生表明，早期发育可能受到干扰，因此研究中的胎儿可能无法代表一般人群。因此，未来需要进行更多健康胎儿人群中颈肋频率的研究，以评估它们作为医疗风险指标的潜力。
