Ush1g, also known as SANS, is a gene whose protein product is involved in multiple important biological functions. It is known to regulate pre-mRNA splicing by mediating the intra-nuclear transfer of tri-snRNP complexes [3]. The protein SANS is a scaffold of the ciliary/periciliary Usher syndrome (USH) protein network in photoreceptor cells and links this network to the intraflagellar transport module by directly binding to IFT-B proteins [6]. USH is the most common genetic condition causing combined hearing and vision loss [1,4].

In a mouse model, a spontaneous allelic variant in Ush1g led to the introduction of a stop codon, resulting in null mice (Ush1gbw/bw) with auditory and vestibular defects commonly seen in mutations affecting inner-ear hair-cell function. These mice had disorganized and split hair bundles, altered distribution of stereocilia-related proteins, and disrupted kinocilium displacement, suggesting Ush1g is essential for forming the hair cell's kinocilial links [5]. A human study found a novel homozygous missense variation in Ush1g causing an atypical USH1G-related phenotype with profound hearing impairment, relatively mild retinitis pigmentosa, but no vestibular dysfunction [2]. Another study identified compound heterozygous mutations in Ush1g in a family with autosomal recessively inherited non-syndromic hearing loss, expanding the phenotypic spectrum of Ush1g mutations [7].

In conclusion, Ush1g plays a crucial role in pre-mRNA splicing, ciliary transport, and the proper functioning of inner-ear hair cells. Mouse models have been instrumental in revealing its role in auditory and vestibular function, while human studies have shown its association with Usher syndrome and non-syndromic hearing loss. Understanding Ush1g's function provides insights into the pathophysiology of these disorders.