Here I present: “Glucose Transport Defect (blood-brain barrier)”, Victor McKusick, Mendelian Inheritance in Man’, 1966.
INTRODUCTION.
The blood–brain barrier (BBB) is a highly selective semipermeable border of endothelial cells that regulates the transfer of solutes and chemicals between the circulatory system and the central nervous system, thus protecting the brain from harmful or unwanted substances in the blood.
The blood–brain barrier (BBB) is formed by endothelial cells of the capillary wall, astrocyte end-feet ensheathing the capillary, and pericytes embedded in the capillary basement membrane. This system allows the passage of some small molecules by passive diffusion, as well as the selective and active transport of various nutrients, ions, organic anions, and macromolecules such as glucose and amino acids that are crucial to neural function.
Glucose Transport Defect (GLUT1) deficiency syndrome-1 is caused by heterozygous mutation in the gene encoding the GLUT1 transporter (SLC2A1) on cytogenetic location 1p34.2 and genomic coordinates 1:42,925,353-42,958,868 . The screenshot of the SLC2A1 gene is shown BELOW of 33,516 bp (base pairs) of DNA sequence length. Nine (9) other genes besides SLC2A1 in the 1p34.2 cytogenetic location are shown BENEATH. 
| Coordinate | Symbol | Genomic Name. |
| 1:42,733,093 | CLDN19 | Claudin 19 |
| 1:42,746,374 | P3H1 | Prolyl 3-hydroxylase 1 |
| 1:42,807,052 | SVBP | Small vasohibin-binding protein |
| 1:42,817,122 | ERMAP | Erythroblast membrane-associate protein |
| 1:42,925,353 | SLC2A1 | Solute carrier family 2. member 1 |
| 1:43,164,174 | EBNA1BP2 | EBNA1-binding protein 2 |
| 1:43,172,330 | CFAP57 | Cilia- and flagella-associated protein 57 |
| 1:43,281,877 | C1orf210 | Chromosome 1 open reading frame 210 |
| 1:43,300,982 | TIE | Tyrosine kinase with immunoglobulin |
| 1:43,337,818 | MPL | MPL protooncogene |
