Brachydactyly type B1 (Brachydactyly type B1) - Gen ROR2.  

Brachydactyly defines a group of inherited malformations characterized by the shortening of fingers due to abnormal development of the phalanges and / or metacarpals. Brachydactyly type B1 is a very rare congenital malformation characterized by hypoplasia or aplasia of the terminal parts of the fingers 2 to 5, with complete absence of nails.

This process is due to mutations in the gene ROR2, located on the long arm of chromosome 9 (9q22). This gene encodes a protein whose function is unclear. The ROR2 protein is part of a family of proteins known as protein receptor kinases (RTKs), which play a role in chemical signaling within cells. Receptor protein kinases are involved in many cellular functions including growth and proliferation, differentiation, survival and cell movement. It is believed that ROR2 protein plays an essential role in the development before birth. It is involved in a signaling pathway called chemical Wnt signaling, which affects many aspects of embryonic development. This pathway controls the activity of the genes needed at specific times during development and regulate interactions between cells as the organs and tissues are formed.

They have identified several mutations in the gene ROR2 in people with brachydactyly type B1. These mutations are described as "gain of function mutations." Although these genetic changes are likely to cause the protein ROR2 be continuously active, it is not clear how the overactive protein disrupts the formation of bones of the hands and feet.

B1 brachydactyly type is inherited as an autosomal dominant, which means that a copy of an altered gene in each cell is sufficient to express the disease.

Tests performed in IVAMI: in IVAMI perform detection of mutations associated with brachydactyly type B1, by complete PCR amplification of the exons of the gene ROR2, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).