The identification of the causative gene has enabled the development of many genetically modified organisms including nematodes (roundworms), Drosophila fruit flies, and genetically modified mammals including mice, rats, sheep, pigs and monkeys that express mutant huntingtin and develop progressive neurodegeneration and HD-like symptoms.Research is being conducted using many approaches to either prevent Huntingtons disease or slow its progression. Disease-modifying strategies can be broadly grouped into three categories: reducing the level of the mutant huntingtin protein (including gene splicing and gene silencing); approaches aimed at improving neuronal survival by reducing the harm caused by the protein to specific cellular pathways and mechanisms (including protein homeostasis and histone deacetylase inhibition); and strategies to replace lost neurons. In addition, novel therapies to improve brain functioning are under development; these seek to produce symptomatic rather than disease-modifying therapies, and include phosphodiesterase inhibitors.The CHDI Foundation funds a great many research initiatives providing many publications. The CHDI foundation is the largest funder of Huntingtons disease research globally and aims to find and develop drugs that will slow the progression of HD. CHDI was formerly known as the High Q Foundation. In 2006, it spent $50 million on Huntingtons disease research. CHDI collaborates with many academic and commercial laboratories globally and engages in oversight and management of research projects as well as funding. Reducing huntingtin production
Gene silencing aims to reduce the production of the mutant protein, since HD is caused by a single dominant gene encoding a toxic protein.
It does not recognise deviations in other spatial axes, asymmetric deviations, functional faults and other therapy-related features. Angles classification system also lacks a theoretical basis; it is purely descriptive. Its much-discussed weaknesses include that it only considers static occlusion, it does not account for the development and causes (aetiology) of occlusion problems, and it disregards the proportions (or relationships in general) of teeth and face. Thus, many attempts have been made to modify the Angle system or to replace it completely with a more efficient one, but Angles classification continues be popular mainly because of its simplicity and clarity.Well-known modifications to Angles classification date back to Martin Dewey (1915) and Benno Lischer (1912, 1933). Alternative systems have been suggested by, among others, Simon (1930, the first three-dimensional classification system), Jacob A. Salzmann (1950, with a classification system based on skeletal structures) and James L. Ackerman and William R. Proffit (1969). Incisor classification
Besides the molar relationship, the British Standards Institute Classification also classifies malocclusion into incisor relationship and canine relationship. Class I:
The lower incisor edges occlude with or lie immediately below the cingulum plateau of the upper central incisors
Class II:
The lower incisor edges lie posterior to the cingulum plateau of the upper incisors
Division 1 – the upper central incisors are proclined or of average inclination and there is an increase in overjet
Division 2 – The upper central incisors are retroclined. The overjet is usually minimal or may be increased. Class III:
The lower incisor edges lie anterior to the cingulum plateau of the upper incisors.