Variations in genes encoding for the enzymes responsible for synthesizing the linker region of proteoglycans may result in recessive conditions known as "linkeropathies". The two phenotypes related to mutations in genes B4GALT7 and B3GALT6 (encoding for galactosyltransferase I and II respectively) are similar, characterized by short stature, hypotonia, joint hypermobility, skeletal features and a suggestive face with prominent forehead, thin soft tissue and prominent eyes. The most outstanding feature of these disorders is the combination of severe connective tissue involvement, often manifesting in newborns and infants, and skeletal dysplasia that becomes apparent during childhood. Here, we intend to more accurately define some of the clinical features of B4GALT7 and B3GALT6-related conditions and underline the extreme hypermobility of distal joints and the soft, doughy skin on the hands and feet as features that may be useful as the first clues for a correct diagnosis.
Keywords: Ehlers–Danlos syndrome (EDS); SEMDJL-Beighton type); beta-1,3-galactosyltransferase 6 (B3GALT6); beta-1,4-galactosyltransferase 7 (B4GALT7); doughy skin on the hands and feet; extreme laxity of distal joints; soft; spEDS-B3GALT6; spEDS-B4GALT7; spondylodysplastic Ehlers–Danlos syndrome (spEDS); spondyloepimetaphyseal dysplasia with joint laxity (SEMDJL1.