Biallelic variants in CCN2 underlie an autosomal recessive kyphomelic dysplasia.

Kyphomelic dysplasia is a rare heterogenous group of skeletal dysplasia, characterized by bowing of the limbs, severely affecting femora with distinct facial features. Despite its first description nearly four decades ago, the precise molecular basis of this condition remained elusive until the recent discovery of de novo variants in the KIF5B-related kyphomelic dysplasia. We ascertained two unrelated consanguineous families with kyphomelic dysplasia.

Euclidean rigor and the curious case of the (missing) reflex angle.

I examine a known case of undergeneralization in Euclid's Elements arising from Euclid's non-cognizance of the reflex angle. Sir Thomas Heath (1956) attributed the undergeneralization to Euclid's lack of awareness, an assessment that I dispute. Non-recognition of reflex angles also leads to Proclus' four-sided triangles which violate an essential property of triangles.