Here I present: “Huntington’s Disease“, Victor McKusick, Mendelian Inheritance in Man’, 1966. (HD).
INTRODUCTION.
Neurologist George Huntington was the first to describe the condition known as Huntington’s Disease (HD) which is an autosomal dominant progressive neurodegenerative disorder with a distinct phenotype characterized by chorea, dystonia, incoordination, cognitive decline, and behavioral difficulties. There is progressive, selective neural cell loss and atrophy in the caudate and putamen.
Huntington’s Disease (HD) is an incurable neurodegenerative disease that is mostly inherited. The earliest symptoms are often subtle problems with mood or mental/psychiatric abilities. A general lack of coordination and an unsteady gait often follow. It is also a basal ganglia disease causing a hyperkinetic movement disorder known as chorea. As the disease advances, uncoordinated, involuntary body movements of chorea become more apparent. Physical abilities gradually worsen until coordinated movement becomes difficult, and the person is unable to talk. Mental abilities generally decline into dementia, depression, apathy, and impulsivity at times. The specific symptoms vary somewhat between people. Symptoms usually begin between 30 and 50 years of age and can start at any age but are usually seen around the age of 40. The disease may develop earlier in each successive generation. About eight percent of cases start before the age of 20 years, and are known as juvenile HD.
There is evidence Huntington’s Disease (HD) is caused by a heterozygous expanded trinucleotide repeat (CAG)n, encoding glutamine, in the gene encoding Huntington’s Disease (HD). In normal individuals, the range of repeat numbers is 9 to 36. In those with HD, the repeat number is above 37. The HD gene is on cytogenetic location 4p16.3 and genomic coordinates 4:3,074,681-3,243,960. The screenshot of the the HD gene 169,280 bp (base pairs) of DNA sequence length is shown BELOW. Nine (9) other genes besides HD in the 4p16.3 cytogenetic location are listed BENEATH.
| Coordinate | Symbol | Genomic Name |
| 4:2,843,844 | ADD1 | Adducin-1, alpha |
| 4:2,930,567 | TETRAN | Tetracycline transporter-like protein |
| 4:2,937,936 | NOP14 | NOP14 nucleolar protein |
| 4:2,963,571 | GRK4 | G protein-coupled receptor kinase 4 |
| 4:3,074,681 | HD | Huntington’s Disease (HTT) |
| 4:3,285,891 | RGS12 | Regulator of G protein signaling 12 |
| 4:3,441,005 | HGFAC | Hepatocyte growth factor activator |
| 4:3,463,306 | DOK7 | Downstream of tyrosine kinase 7 |
| 4:3,503,612 | LRPAP1 | LD lipoprotein-related protein-associated protein 1 |
| 4:3,766,385 | ADRA2C | Adrenergic, alpha-2C-, |
