Here I present: “Type-IIIA Usher Syndrome”, Victor McKusick, Mendelian Inheritance in Man’, 1966. IIIA型Usher综合征。
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.
People with Usher syndrome type-III experience hearing loss and vision loss beginning somewhat later in life. Unlike the other forms of Usher syndrome type-III is usually associated with normal hearing at birth. Hearing loss typically begins during late childhood or adolescence, after the development of speech, and becomes more severe over time. By middle age, most affected individuals have profound hearing loss. Vision loss caused by retinitis pigmentosa also develops in late childhood or adolescence. Some people with Usher syndrome type-III develop vestibular abnormalities that cause problems with balance.
There is evidence Usher syndrome type-IIIA (USH3A) is caused by homozygous or compound heterozygous mutation in the CLRN1 gene on cytogenetic location 3q25.1 and genomic coordinates 3:150,926,163-150,972,999. The screenshot of the CLRN1 gene 46,837 bp (base pairs) of DNA sequence length is shown BELOW. Nine (9) other genes besides CLRN1 in the 3q25.1 cytogenetic location are listed BENEATH.
| Coordinate | Symbol | Genomic Name |
| 3:150,541,998 | SERP1 | Stress-associated endoplasmic reticulum protein |
| 3:150,546,787 | EIF2A | Eukaryotic translation initiation factor 2A |
| 3:150,603,321 | SELENOT | Selenoprotein T |
| 3:150,741,125 | SIAH2 | SIAH E3 ubiquitin protein ligase, member 2 |
| 3:150,926,163 | CLRN1 | Clarin 1 |
| 3:151,085,664 | MED12L | Mediator complex subunit 12-like |
| 3:151,197,754 | GPR171 | G protein-coupled receptor 171 |
| 3:151,212,117 | P2RY14 | Purinergic receptor P2Y, G protein-coupled, 14 |
| 3:151,294,086 | GPR87 | G protein-coupled receptor 87 |
| 3:151,326,312 | P2RY13 | Purinergic receptor P2Y13 |
