Question

What are holandric traits?

Answer 1

Hint: Traits are transferred from the parents to the offspring. These traits are generally present in the genes of the parents that are generally inherited in the form of chromosomes. The two chromosomes that are responsible for this kind of inheritance are "X" and "Y".

Complete answer:
Chromosomes are the condensed form of DNA produced during the process of DNA duplication. Humans have 23 pairs of chromosomes out of which one is termed the sex chromosome. The 23rd pair of chromosomes helps us to decide whether the child is male or female. Females have a set of chromosomes that is represented by "XX" whereas males have "XY ''. Females contain the same set of chromosomes which is "X" whereas males contain two different sets which are "X" and "Y". Holandric diseases are mainly linked with the Y chromosome and this chromosome is wholly present only in the males.

Holandric inheritance is also known as Y linkage and it describes the traits that are produced on the gene that is present on the Y chromosome. Since, Y - chromosome is present only in males so these traits are transmitted from father to son. These traits are absent from daughters of trait carriers; instead, the daughters are phenotypically normal and do not have affected offspring.

A number of genes are known to be Y- linking out of which some are:
- ASMTY stands for acetylserotonin methyltransferase
- TSPY that stands for testis-specific protein
- $IL_3RAY$ that stands for interleukin 3 - receptor
- TDF that stands for testis determining factor
- DAZ that stands for deleted in azoospermia
- SRY that stands for sex-determining region

Note: Y linkage was established by the pioneer, Curt Stern which was earlier hard to prove. Later in the 1950s human pedigrees, many genes that are present on the Y chromosomes were considered incorrect. Hairy ears in humans are an example of a gene that was once thought to be Y- linked but later it was discreated due to advancement in DNA sequencing.