Written by Liz Marfia-Ash (GRIN2B parent) with contributions from Heather Rocha (Genetic Counselor at Simon’s VIP Connect)

Personal note – If there’s one thing I’ve learned since receiving my child’s diagnosis, it’s that Genetics are complicated.  I’ve read and re-read all the terms endlessly.  This is my attempt at simplifying the terms for us parents who are not experts at Genetics.  If you would like a more detailed, scientific explanation, I would recommend picking up a copy of Genetics for Dummies or visit


Chromosomes that determine sex

Each person has 46 chromosomes that come in pairs – 23 are from your mother and 23 from your father.  Chromosomes 1 through 22 are the same between men and women. The 23rd pair are the “sex chromosomes” which determine whether a person will be a male or 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):

Each chromosome has a short arm (P) and a long arm (Q).



The GRIN2B gene is located on the short arm (p arm) of chromosome 12. The exact location is 12p13.1.

GRIN2B Gene Location
Image from Gene Cards

Each chromosome contains tightly wound strands of DNA

Each chromosome contains tightly wound strands of DNA, which contain the instructions that make each of us unique.


Chromosome US National Library of Medicine image

From – Each chromosome contains genes. The Human Genome Project has estimated that humans have between 20,000 and 25,000 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, thymine, cytosine and guanine . These four letters are put together into different combinations and make up each of our genes.  **Remember these letters.  These will be important later when we discuss your child’s genetic lab report on Genetics and GRIN2B.

Genes provide instructions for creating proteins that play a critical role in many functions of the body. When a mutation of a gene occurs, the protein product may be faulty, inefficient, or absent. Depending upon the functions of the particular protein, this can affect many organ systems of the body.

Children Helping Make CookiesREAL LIFE EXAMPLE:  If you’re making cookies and you leave out baking soda, you will still end up with cookies.  They are just going to taste different from what you expected.  It’s the same situation when an individual has a GRIN2B variation.  One ingredient in your child was either left out or changed slightly.  You still end up with a child, they just function differently from what you expected.

It’s possible to have a mutation that has no effect.  These types of changes are called “variants of uncertain significance.”  You may see this on your child’s lab report.  Since the function of the GRIN2B gene is tied to memory and learning, any variations can have a significant impact on the individual.

Still confused?  Please let us know if there is a term we missed or something on this page you feel needs more explanation.  We appreciate your feedback!  Contact us at