Sex Determination and Genetics

The Correct Answer is A

• The Sex-Determining Region (SRY) is a gene that encodes a transcription factor that is a member of the high mobility group HMG-box family of DNA binding proteins.
• The main function of the SRY protein is to initiate male sex determination as a transcriptional activator, which regulates a genetic switch in male development.
  
• The great majority of patients with 46,XY sex reversal remain to be explained because only 15 % of them carry mutations in SRY (or more rarely in SOX9). Moreover, in a few cases, the SRY protein was expressed in the dysgenetic gonads. SRY downstream genes must be discovered to explain the majority of these cases of sex reversal.
• the SRY protein regulates genes that control the development of the testes.
• (47XXY) Classic Klinefelter syndrome arises from meiotic nondisjunction of the X chromosome. These patients usually have small firm testes, low serum testosterone levels, and azoospermia.
• The steroidogenic acute regulatory (StAR) is expressed in steroidogenic tissues in response to agents that stimulate steroid production, and mutations in the StAR gene result in the disease congenital lipoid adrenal hyperplasia, in which steroid hormone biosynthesis is severely compromised.

Category: