The field of rare diseases is complex and heterogeneous and suffers from a deficit of scientific and medical knowledge .The landscape of rare disease is constant evolving the new rare diseases and conditions being reported and identified regularly in medical literature. Apart from a few rare diseases where significant progress has been made, still the field is nascent stage. For a long time, doctors, researchers and policy makers were unaware of rare diseases and until very recently no real research or public health policy concerning issues related to the field .This possess challenges in development of comprehended policy on rare diseases. Nevertheless, it is important to take step, in the short as well as long term, with the objective of talking rare diseases in a comprehensive and holistic manner

Gene Therapy mainly involves the introduction or alteration of genetic material within a cell or organism with an intention of curing the disease. Both gene therapy and cell therapy are overlapping fields of biomedical research with the goals of repairing the direct cause of Genetic diseases in DNA or cellular population respectively, the discovery of recombinant DNA technology in the 1970s provided tools to develop gene therapy efficiently. Scientists use these techniques to readily manipulate viral genomes, isolate genes and identify mutations involved in human diseases, characterize and regulate gene expressions, and engineer various non- viral and viral vectors. Various long-term treatments for anaemia, haemophilia, cystic fibrosis, muscular dystrophy, Gauscher’s disease, lysosomal storage diseases, cardiovascular diseases, diabetes and diseases of bones and joints are resolved through successful gene therapy.

Neurological disorders are the diseases associated with the spine, brain and the nerves that connect them. It affects the body nervous system. Aicardi-Goutieres, Reflex Sympathetic Dystrophy, Acarida syndrome are few rare specified neurological disorders to specify. The central nervous system affected by Rare Neurological Disorders usually develops in infancy and is inherited in an autosomal recessive manner. There are various kinds of symptoms which are categorized in three main stages that provide a general basis for diagnosing individuals with LS. The symptoms of the stage I are characterised as stunted growth, vomiting, and diarrhoea.  Symptoms exhibited in stage II are example such as optic atrophy, uncoordinated movement, dystonia, hypotonia, and peripheral neuropathy. The symptoms of stage III are dysarthria, acute muscle and dysphagia, atrophy is common, with death being the outcome. It is necessary to study the physiological defects of brain and muscle structures in LS for proper diagnosis and treatment.

Breakdown in regular process of blood cell growth and development leads to the cell types production in abnormally large quantities or in abnormal form. Some rare blood disorders especially those that are gene-based are easy to identify with a simple test, while others require substantial analyst work to successfully diagnose. Due to the large number of blood conditions common and uncommon, haematologists tend to be skilled investigators because they need to be specialists in differential diagnosis. This leads to blood cancers or other blood disorders. The most common blood cancers include leukemia, lymphomas, and multiple myeloma. There are few common blood disorders also. These include various myeloproliferative neoplasms, histiocytosis, and paroxysmal nocturnal hemoglobinuria.

Abnormality is also called as dysfunctional behaviour which refers to the behavioural characteristic assigned to those with conditions regarded as rare or dysfunctional. Behaviour is considered to be abnormal when it is atypical or out of the normal or usual, it consists of unpleasant behaviour, and results in deterioration in the individual's functioning. Abnormality is one, which is considered as different from specific ethical social and cultural expectations. These expectations are broadly dependent on age, gender, traditional and societal categorizations. The definition of abnormal behaviour is an often debated issue in abnormal psychology because of these subjective variables.

Metabolism is the chemical process which our body uses to transform the food we eat into the form energy or fuel that keeps us alive and energetic too. When the metabolism processes fails a metabolic disorder causes and results in the body to have either too high or too little of the essential materials needed to stay healthy. Our body is very sensitive to mistakes or errors in metabolism. The body must have amino acids and many types of proteins to perform all its metabolic functions.  Calcium, potassium, and sodium ions are utilized by our brain to generate electrical impulses and to send signals, and also lipids and fatty acids to maintain a healthy nervous system.  

The majority of rare diseases affect children, most of whom have an underlying genetic cause for their condition. However, making a molecular diagnosis with current technologies and knowledge is often still a challenge. Pediatric genomics is rapidly evolving field but it is not well developed, that tackles this problem by incorporating next-generation sequencing technologies, especially whole-exome sequencing and whole-genome sequencing, into research and clinical workflows. This difficult multidisciplinary approach, combined with the ascending availability of population genetic data variation, has already resulted in an increased discovery rate of causative genes and in improved diagnosis of rare pediatric disease. Substantially, for affected individual family members, a good and thorough understanding of the genetic basis of rare disease translates to more perfect prognosis, management, surveillance and genetic advice; stimulates research into new therapies; and enables provision of better support.

A clinical trials are the experimental designed to determine various scientific and consequence aspects of proposed treatment. It is important to remember that there is no guarantee a proposed treatment will be effective. Families should be prepared to balance the hope of participating in a clinical trial with the understanding that the therapy may not be optimal and could result in a serious negative outcome. Since some rare diseases can progress quickly, families often are willing to participate in risky, unknown treatments. Before agreeing to participate, everyone involved should fully understand these risks by carefully reading the consent documents and asking questions of the trial investigators. Most clinical trials related to treatments of rare diseases goes through 3 major phases.

Orphan medicinal products are intended for the analysis, prevention or treatment of dangerous or very serious conditions that affect no more than 5 in 10,000 people in the European Union. Patients suffering from rare diseases deserve the same quality of treatment as other patients within the European Union. Given the small numbers of patients affected by rare diseases, the pharmaceutical industry has been unwilling in the past to invest in the research and development of medicinal products to treat them. The EU introduced new legislation in 2000 with the aim of providing incentives for the development of medicines for rare diseases (so-called orphan medicinal products).

An orphan drug is referred medicinal agent which has been developed to treat a rare medical illness or situation, the condition itself being defined to as a rare disease. Rare disease, also known as an "orphan disease", is any type of disease which affects a small percentage of the population. Majority of rare diseases are genetic, and hence are present throughout the individual's entire life, even if symptoms don’t appear immediately. Many rare diseases appear early in life, and about 30 % of children with rare diseases will die before getting 5 year old. With only a solo diagnosed patient, ribose-5-phosphate isomerase deficiency is presently considered to be the rarest genetic disease. No single cut-offs number has been decided upon for which a disease is considered rare. An illness may be considered rare in one part of the world, or in a group of people, but still be common in another country or group of people. According to a research over 55 million people are estimated to suffer from a rare disease in Europe and in the US, global estimates are between 5000 to 7000 rare diseases and new rare diseases are revealed every week and for many treatments is not available.

Diagnosis and the treatment of a rare disease become complex because of the circumstances that numerous health care providers may have restricted involvement with the identification of the disease condition with the diagnosis of rare diseases. Additionally, analysis before manifestation onset or diagnosis early stage in the disease can be challenging. Biopharmaceutical experts in the field have utilized new advances and the developing investigative comprehension of many rare diseases to develop and diagnose ground breaking therapies over the last 10 years. In 2015 alone, about half (47%) of novel latest drug approvals were for rare diseases. Disease specific therapies need to be developed for productive results in treatment of Rare Diseases.

Globally, about one-third of human deaths are attributable to infections. In addition, the so-called non-infectious causes of death often have a mysterious infectious etiology. Many rare diseases or orphan diseases caused by infectious agents rather than genetic or environmental factors.

There are around 7,000 rare diseases, which from a regulatory outlook are defined as those diseases where there are less than 200,000 patients in the US or that affect no more than five in 10,000 of the general population in the EU. Orphan drugs are medicinal products envisioned for diagnosis, prevention, and treatment of life-threatening rare diseases. They are "orphans" because the pharmaceutical industry has little interest under normal market conditions in developing and marketing drugs intended for only a small number of patients suffering from very rare conditions

Allergy is one of the most adverse immune reaction faced by worldwide   population which is next accompanied by inflammation. The set of conditions caused by Hypersensitivity reactions of the immune system in response to any foreign substance is called allergy/ allergic diseases. It may arise due to environmental or genetic factors. The causative agents are known as allergen and they may be food, drug, dust, pollen, animal dander &fur etc. varying for each individual. Most allergen immunotherapies are the advanced therapeutics method to treat the allergies. Allergic and Inflammatory Reactions are caused by the immune system but if the reaction becomes adverse then the condition becomes chronic for an individual. The causative agents for such adverse reactions could be genetic, environmental, pathogenic and synthetic compounds. The localized body part which gets hot, swollen, red and painful after an injury or infection is an condition termed as inflammation and it might be due to allergy: Allergic inflammation or due to tumour. Inflammation can be   chronic or acute and it consists of different types based on the part of inflammation.