Kabuki syndrome

1. Deoxyribonucleic acid (DNA)
DNA (short for Deoxyribonucleic Acid) is an organic molecule that determines the unique and individual characteristics of all living beings. The individuality of each species and each individual is determined by the composition of DNA, which is based on four information blocks called nitrogenous bases or nucleotides.
Bases have diferent names: Adenine, Guanine, Cytosine and Thymine, or A, G, C, T for short. The bases are linked together in a certain way, giving rise to the ladder-like structure of DNA. The bases form the rungs of the ladder, and on either side of the ladder are a sugar and a phosphate bond, which build up what we call the double helix found in all cells of all living things. The only way the rungs can hold together is when the base pairs AT/TA and CG/GC are linked together, otherwise it would be like two puzzle pieces that don't fit together.

DNA is found in the nucleus of all nucleated cells. In humans, the DNA molecule is 3 trillion base pairs long and this amount of information is the same in each of the 30 trillion active cells in a person's body at any given time. This vast expanse of information is the instructions that tell the body what we look like, our enzymes and proteins, our hair color or ability to gain or lose weight. All of this is determined by the information contained in DNA. The set of these instructions is called the genome. If the 3 trillion base pairs of information were printed on DIN-A4 sheets of paper, we would have a book more than 2 meters wide.
From a scientific point of view, no two people share the same sequence of their DNA molecule, except perhaps for identical (monozygotic) twins. On the other hand, it is also a scientific dogma that the DNA sequence is the same in every person in the world in 99.9% of the bases. How can these two premises be true? The answer is in numbers. What is left over from 99.9%? This small percentage of 0.1% of 3 billion base pairs is 3 million! There are 3 million base pairs in everyone that make him different from everyone else, while there are 99.9% of base pairs that are shared with the rest of humanity.
Overall, biology is the most conservative process. Each person must have the codes for proteins and enzymes that function properly or there will be significant consequences, although there is also a margin for variability. There are traits that distinguish us visibly (phenotypic variation) such as eye and skin color, hair color and texture, height and weight. And other traits that distinguish us genetically (genotypic variation), such as ABO blood type, RH factor, and organ transplant antibodies. There are three million points of variability among the 29,970,000,000 other bases, a little bit here and there along the DNA ladder that allows both premises to be possible and real.