Lmx1ab

Lmx1ab is not an officially recognized gene symbol in major human genome databases. In practice, the label is sometimes encountered as a concatenation or shorthand referring to the two related vertebrate transcription factors LMX1A and LMX1B, which are encoded by separate genes. Standard references treat LMX1A and LMX1B as distinct members of the LIM homeobox gene family.

LMX1A and LMX1B encode transcription factors characterized by two LIM domains and a central homeodomain, enabling DNA binding and regulation of target genes. They play important roles in neural development and organogenesis. LMX1A is implicated in midbrain dopaminergic neuron development and may contribute to other neural patterning processes, while LMX1B is essential for dorsal identity in limb development and contributes to kidney and craniofacial development.

Expression patterns differ: LMX1A is expressed in the dorsal neural tube and developing midbrain, among other neural tissues, whereas LMX1B is prominent in dorsal limb mesenchyme, the developing digits, and related structures. Both genes participate in broader transcriptional networks that guide cell fate and regional identity.

Clinical significance is most clearly established for LMX1B, where pathogenic variants cause nail-patella syndrome in humans, a pleiotropic skeletal and renal disorder. LMX1A has been studied for its role in neural development and disease susceptibility, but no single definitive Mendelian disorder is widely attributed to it.

Nomenclature notes: when Lmx1ab appears in literature or databases, verify species and database conventions to determine whether it denotes LMX1A, LMX1B, a combined family reference, or a misannotation. See also LMX1A and LMX1B for detailed gene-specific information.