Here I present: “Maple Syrup Urine Disease”, Victor McKusick, Mendelian Inheritance in Man’, 1966. (MSUD) icd10=E71.0
INTRODUCTION.
The major clinical features of maple syrup urine disease (MSUD) are mental and physical retardation, feeding problems, and a maple syrup odor to the urine. The keto acids of the branched-chain amino acids (BCAA) are present in the urine, resulting from a block in oxidative decarboxylation.
There are four (4) clinical subtypes of MSUD: 1. the classic neonatal severe form, 2. an intermediate form, 3. an intermittent form, 4. and a thiamine-responsive form.
There is evidence maple syrup urine disease type-IB (MSUD) is caused by homozygous or compound heterozygous mutation in the BCKDHB gene, which encodes branched-chain alpha-keto acid dehydrogenase on cytogenetic location 6q14.1 and genomic coordinates 6:80,106,610-80,466,676. The screenshot of the BCKDHB gene 360,067 bp (base pairs) of DNA sequence length is shown BELOW. Nine (9) other genes besides BCKDHB in the 6q14.1 cytogenetic location are listed BENEATH.
| Coordinate | Symbol | Genomic Name |
| 6:79,484,991 | LCA5 | Lebercilin |
| 6:79,537,633 | SH3BGRL2 | SH3 domain-binding glutamic acid-rich protein-like protein 2 |
| 6:79,914,814 | ELOVL4 | Elongation of very long chain fatty acids 4 |
| 6:80,004,649 | TTK | TTK protein kinase |
| 6:80,106,610 | BCKDHB | Branched chain keto acid dehydrogenase E1, beta polypeptide |
| 6:81,745,730 | TENT5A | Terminal nucleotidyltransferase 5A |
| 6:82,169,987 | IBTK | Inhibitor of Bruton agammaglobulinemia tyrosine kinase |
| 6:82,362,983 | TPBG | Trophoblast glycoprotein |
| 6:82,880,802 | UBE3D | Ubiquitin protein ligase E3D |
| 6:83,067,671 | DOP1A | DOP1 leucine zipper-like protein A |
