<unk>  is an autosomal recessive disorder caused by a novel loss-of-function mutation in the matrix Gla protein gene (MGP). MGP protein resides in the extracellular matrix and is implicated in inhibiting calcification though the repression of bone morphogenetic protein 2 (BMP2). Mutations resulting in loss of consensus donor splice site at exon 2-intron 2 junctions result in significant diffuse calcification of soft tissue cartilage. Extensive diffuse cartilaginous calcification is present in MGP-knockout mice, manifesting in vascular media replacement with a cartilaginous, chondrocyte-like matrix, and ultimately premature death. Conversely, over expression of extracellular MGP effectively abolishes calcification in chondrocytes, suggesting that MGP may function in inhibiting passive calcification in soft tissues. Recent evidence suggests MGP is a vitamin K dependent protein synthesized by chondrocytes and vascular smooth muscle cells, where it potentiates the inhibition of cartilaginous and arterial calcification. Thus, potential vitamin K deficiency, via nutritional deficiency or coumarin-derivative use, would render MGP uncarboxylated and inactive, thus diminishing biological function. Arterial calcification resulting from MGP inactivation results in inimical prognosis, commonly seen in patients with diabetes, atherosclerosis, and renal dysfunction.
Keutel syndrome
Fryns-Aftimos syndrome
Lelis syndrome
Jeavons syndrome
Patau syndrome
Yunis–Varon syndrome
McGillivray syndrome
Bruck syndrome