Genetics 101

This is written as a guide to help parents better understand the specific mutation mentioned on their child’s genetic report. When you do not have knowledge about genes and chromosomes, it can be overwhelming and frustrating trying to interpret the results. This is written to try to help explain chromosomes, genetic mutations and specifically details about the SETBP1 gene.

Chromosome Basics

Humans typically have 23 pairs of chromosomes totaling 46 chromosomes – 23 coming from the mother and 23 coming from the father. Chromosomes 1 through 22 are the same between males and females. The 23rd pair of chromosomes are the “sex chromosomes” which determine whether a person will be a male or a female. Females have two X chromosomes and males have one X and one Y chromosome.

Each chromosome has a short arm (p) and a long arm (q).

Hundreds and sometimes thousands of genes can be found on one chromosome. SETBP1 is a gene located on the long arm (q arm) of chromosome 18. The exact location is 18q12.3.

There are many chromosomes found in the nucleus, a protective compartment, of every cell. The chromosomes are structures that help organize the DNA. The DNA is the language or code that provides the instructions that tell the body how to grow, function and respond to the environment. The genes are specific segments of DNA which have a specific job to do.

What are genes

From simonsvipconnect.org: Each cell in the human body contains about 25,000 to 35,000 genes. Genes carry the information that determines your traits, and how your body grows and develops. Genes are made up of DNA, which has its own alphabet made of just 4 letters — A, T, C, and G. These stand for the 4 chemical building blocks – adenine (A), thymine (T), cytosine (C) and guanine (G). These four letters are put together into different combinations in a specific order to make up each of your genes. The gene’s job is to create a specific protein. Just like with words, if a letter is deleted, added, or located in the wrong place, the message to create the protein may not make sense and the message may not be understood by the cell. This is what can happen when a mutation in a gene occurs – the protein product may be inefficient, faulty, or absent. Note: Not all mutations or DNA changes are harmful.

The SETBP1 gene’s job is to create a specific protein called SETBP1 protein. Since individuals inherit 2 copies of every chromosome, they have 2 copies of every gene including SETBP1. SETBP1 haploinsufficiency disorder is caused by a SETBP1 mutation affecting one copy of the SETBP1 gene which reduces the amount of SETBP1 protein produced by the body. This is also referred to as haploinsufficiency.