LMX-1.2 is essential for the specification of dorsal limb fate. It is expressed in most of tissues, with highest levels in testis, thyroid, duodenum, skeletal muscle, and pancreatic islets. Defects in LMX-1.2 are the cause of nail-patella syndrome (NPS), also known as Onychoosteodysplasia. NPS is a disease that causes abnormal skeletal patterning and renal dysplasia. LIM homeodomain proteins are characterised by the presence of 2 tandem cysteine/histidine-rich, zinc-binding LIM domains.