Here I present: “Type-IIB Usher Syndrome”, Victor McKusick, Mendelian Inheritance in Man’, 1966.
INTRODUCTION.
Researchers have identified four (4) major types of Usher syndrome, designated as types I, II, III and IV. These types are distinguished by the severity of hearing loss, the presence or absence of balance problems, and the age at which signs and symptoms appear. The types are further divided into subtypes based on their genetic cause.
Usher syndrome type-II is characterized by hearing loss from birth and progressive vision loss that begins in adolescence or adulthood. The hearing loss associated with this form of Usher syndrome ranges from mild to severe and mainly affects the ability to hear high-frequency sounds. For example, it is difficult for affected individuals to hear high, soft speech sounds, such as those of the letters d and t. The degree of hearing loss varies within and among families with this condition, and it may become more severe over time. Unlike the other forms of Usher syndrome type-II is not associated with vestibular abnormalities that cause difficulties with balance.
Usher syndrome type-II can result from mutations in three genes; USH2A gene mutations account for most cases of type-II. Type-IIB Usher syndrome (USH2B) results from mutation in a locus mapped to cytogenetic location 3p24.2-p23 but the exact genomic coordinates of a particular gene have not been identified in the 387,133 bp (base pairs) of DNA sequence length. Ten (10) other genes besides USH2B in the 3p24.2-p23 cytogenetic location are listed BELOW
| Coordinate | Symbol | Genomic Name |
| 3:23,203,098 | UBE2E2 | Ubiquitin-conjugating enzyme E2 E2 |
| 3:23,800,001 | FEB9 | Febrile seizures, familial, 9 |
| 3:23,805,955 | UBE2E1 | Ubiquitin-conjugating enzyme E2 E1 |
| 3:23,889,951 | NKIRAS1 | NFKB inhibitor-interacting Ras protein 1 |
| 3:23,916,545 | RPL15 | Ribosomal protein L15 |
| 3:23,945,286 | NR1D2 | Nuclear receptor subfamily 1, group D, 2 |
| 3:24,117,153 | THRB | Thyroid hormone receptor, beta |
| 3:24,829,321 | RARB | Retinoic acid receptor, beta polypeptide |
| 3:25,597,905 | TOP2B | Topoisomerase (DNA) II, beta |
| 3:25,718,944 | NGLY1 | N-glycanase 1 |
