A gene is a small piece of DNA that assembles a sequence of several amino acids in the correct order to produce one of many proteins in humans. These proteins in turn control the formation and proper functioning of our body for daily activities. Our entire DNA is made up of 4 nucleotide molecules represented by the letters A, T, G and C (like the alphabets A-Z). Just as how the alphabet letters are used in different combinations to generate words with different spellings, the 4 nucleotides are arranged in different combinations to generate the genetic code. Each gene has its own code, which in turns generate specific proteins. Different genes have different sequences of ATGC, which means every protein in the human body has different amino acid sequences. This is the reason why different proteins have different functions in the body.
When the genetic code is transmitted from the parents to their children, all the ATGC codes for different genes are preserved. However, if the codes are modified by mutations (either spontaneously or through inheritance), the “spelling mistake” of the code leads to change in protein sequence, which in turn affects protein function. This change can either mean an increased or reduced protein function that may have devastating effects on the normal functioning of the body.
The KCNB2 gene produces the Kv2.2 protein that is essential for proper functioning of the brain. Like other genes, KCNB2 has a set sequence of ATGC nucleotides, which represents its genetic code. Any change in the genetic code (for example, when the “A” at position 1141 of the genetic code is changed to a “G”) can lead to amino acid sequence change (same example, from “Threonine” to an “Alanine” at position 381) of the protein. 
Such simple substitutions lead to reduced function of the KCNB2 protein in the brain. Since KCNB2 is thought to be important for normal brain development and function, disturbance of KCNB2 protein function may result in the drastic change (in KCNB2’s case, a delay) in patient’s neurological and neurodevelopmental features.
The clinical consequences of all KCNB2 variants are mentioned in the section: “Caregivers - Clinical Characteristics”.