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Congenital stationary night blindness
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<p>Congenital stationary night blindness (CSNB) is a rare non-progressive <a href="/facts/Retina/v0ISNX2S">retinal</a> disorder. People with CSNB often have difficulty adapting to low light situations due to impaired <a href="/facts/Photoreceptor_cell/Ap0DcW5N">photoreceptor</a> <a href="/facts/Neurotransmission/9H38LExu">transmission</a>. These patients may also have reduced visual acuity, <a href="/facts/Myopia/KSqGQPUH">myopia</a>, <a href="/facts/Nystagmus/7Djf4Itt">nystagmus</a>, fundus abnormalities, and <a href="/facts/Strabismus/HzSXdF24">strabismus</a>. CSNB has two forms -- complete, also known as type-1 (CSNB1), and incomplete, also known as type-2 (CSNB2), which are distinguished by the involvement of different retinal pathways. In CSNB1, downstream neurons called <a href="/facts/Retina_bipolar_cell/aUWUNcnn">bipolar cells</a> are unable to detect neurotransmission from photoreceptor cells. CSNB1 can be caused by mutations in various genes involved in neurotransmitter detection, including <a href="/facts/NYX_(gene)/5zgG4w1p"><i>NYX</i></a>. In CSNB2, the photoreceptors themselves have impaired neurotransmission function; this is caused primarily by mutations in the gene <i><a href="/facts/CACNA1F/BxEd1BfR">CACNA1F</a></i>, which encodes a <a href="/facts/Voltage-gated_calcium_channel/H9nAybJJ">voltage-gated calcium channel</a> important for neurotransmitter release. CSNB has been identified in horses and dogs as the result of mutations in <i><a href="/facts/TRPM1/jsjH8w2d">TRPM1</a></i> (Horse, "LP")<i>, <a href="/facts/Metabotropic_glutamate_receptor_6/LMDnekL5">GRM6</a></i> (Horse, "CSNB2")<i>,</i> and <i><a href="/facts/LRIT3/HgtYYHHI">LRIT3</a> (Dog</i>, CSNB)<i>.</i> </p><p>Congenital stationary night blindness (CSNB) can be inherited in an X-linked, <a href="/facts/Autosomal_dominant/DsvtPyQU">autosomal dominant</a>, or <a href="/facts/Autosomal_recessive/DsvtPyQU">autosomal recessive</a> pattern, depending on the genes involved. </p><p>Two forms of CSNB can also affect horses, one linked to the <a href="/facts/Leopard_complex/4XwYIsvV">leopard complex</a> of equine coat colors and the other found in certain horse breeds. Both are autosomal recessives. </p>