≤11 ribs (differential)

≤11 ribs is associated with a number of congenital abnormalities and skeletal dysplasias, including:

• Down syndrome (trisomy 21)
• campomelic dysplasia
• kyphomelic dysplasias
• asphyxiating thoracic dysplasia (Jeune syndrome)
• short rib polydactyly syndromes
• trisomy 18
• chromosome 1q21.1 deletion syndrome​
• atelosteogenesis
• spondylocostal dysostosis
• spondylometaphyseal dysplasia, Sedaghatian type
• Ritscher-Schinzel syndrome

However, it is important to note that up to 8% of individuals have been found to have 11 pairs of ribs, as an anatomic variant, without any apparent deleterious clinical sequelae .