Genetics

Genetics

Hey broritos, Hope u guys had a great Christmas

Today, we are going to talk about genetics. Fret not cuz today’s genetics part will be very straight forward and interesting at the same time.

Now I am going to talk about the location of a gene or in other words locus

Firstly we must learn how to read cytogenetic location of a gene!! So here is a diagram to help u guys with it :)

Cytogenetic location:7q31.2.

We are using CFTR(Cystic fibrosis transmembrane conductance regulator) as an example.The first number 7 indicates the chromosome number. In humans we have 23 pairs of chromosome. So, in this case the CFTR gene is located on the 7th chromosome.

The q represents the arm of the chromosome. Every chromosome has two arms which are p and q. The p represents the short arm and q represents the long arm. Both arms are “divided” by a centromere.Hopefully, the diagram below shows a better illustration.

Next, the number 3 represents the region and 1 represents the band. These region and bands are obtained when the chromosome is stained in a certain way.Then, the bands are visualized under microscope.(region and band number count starts from centromere and ends at the telomere)  After the region and band number, there will be a number after a decimal point, this number indicates the subband which can be visualized under microscope with higher resolution within the normal bands.

Hopefully the above explanation gives a clearer idea on gene location

SO Where is HGD gene found??

Cytogenetic location : 3q13.33

Other than the cytogenetic location, there is also the molecular location which use base pairs to locate the gene.  For the HGD gene, the gene is located base pairs 120,628,167 to 120,682,570 on chromosome 3

Hope the gene location was educational. Now, we are going to talk about autosomal recessive

Remember us saying that the gene is transferred to the affected individual in an autosomal recessive manner!!

Autosomal refers to a mutation in one of the first 22 non-sex chromosome.

So what is recessive?

Genes come in pairs. Therefore, Recessive means that both genes must be defective for the disease to occur.

Lets use this diagram to help us understand recessive

X-dominant gene

x- recessive gene.

XX- unaffected by disease and not a carrier

Xx-unaffected by disease and is a carrier

xx- affected by disease

Only a child with xx be affected with disease.Thus, if both parents are carriers to a defective gene, the child will be 25% likely to inherit the disease, 50% likely to be carriers and 25% likely not to carry the mutant gene.

SOOO , A person must be very unfortunate to inherit an autosomal recessive disease. More so , if it is a rare disease like Alkaptonuria.

WHY ALWAYS ME ??

Currently over 100 mutation of HGD gene has been identified

That's all from us today

Next blog: Pathophysiology

PEACE-OUT

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