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.

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.

The immune system is delegated to defend the body from attacks from outside or inside. Many diseases can affect immune system reducing its ability to defend self or inducing an abnormal response against external or internal antigens. Rare diseases affecting immune system present some issue in common with other rare diseases and some peculiarities due to the huge variability in the disease's expression. However, a correct estimation of the epidemiology of rare disorders is necessary for evaluating the prognosis and the responses to new therapies, for planning proper public health services, and finally to establish fair and sustainable prices for innovative medicines. The immune system is delegated to defend the body from attacks from outside or inside. Many diseases can affect immune system reducing its ability to defend self or inducing an abnormal response against external or internal antigens.

Many rare diseases affect the kidneys and the urinary system, some limited to the urinary system itself (e.g., membranous nephropathy), and some part of a condition (e.g., AL port syndrome) that causes additional symptoms in other organ systems. With varying degrees of severity, these diseases can affect different parts of the urinary system (kidney glomerulus, kidney tubules, urinary tract, etc.) causing numerous symptoms. Several of these diseases occur in the context of inflammation and autoimmune disease (e.g., Good pasture syndrome). Many rare types of vasculitis can also cause major kidney problems (e.g., Henoch-Schönlein purpura nephritis). Disorders of kidney development, kidney metabolism, or substance transport within the kidney also exist. Some are directly heritable diseases caused by genetic defects (e.g., cystinuria). Rare diseases can cause acute kidney damage (which may be repairable), but more often result in chronic kidney disease.

Skin disorders differ significantly in indications and brutality. Rare skin diseases are mostly genetic. Genodermatoses are genetic skin disorders with cutaneous expression.  The Genodermatoses & Rare Skin Diseases therapeutic centres targeted mainly genodermatoses with a high effect on quality of life of patients and of their families and leading to a huge social handicap. There are many rare skin diseases like Atopic dermatitis(categorized by chronic inflammation of the skin), Epidermolysis Bullosa (inherited disorders in which the skin and mucous crusts are very delicate that the lightest touch can cause very painful), Icthyosis (dry, thickened, scaling skin).

The many different types of rare oncological diseases include tumors of the body and hematological disorders of the blood. Although individually these malignancies are rare, as a group, they represent a significant majority of people with cancer.Certain characteristics of these malignancies differentiate them from more common types of cancer. Often, the cancer begins in a type of cell that only rarely becomes cancerous. This can happen in organs that are otherwise common sites of cancer growth. For example, although breast cancer is not a rare disease, angiosarcoma of the breast, which arises in the inner lining of blood vessels, is a rare cancer.

These diseases occur very rarely, consisting of fluid-filled channels they are non-malignant masses or spaces thought to be caused by the abnormal development of the lymphatic system. These formations are usually detectable at birth or after two years of age. Lymphatic malformations can affect any part of the body (except the brain), but they most commonly affect the head and neck. When recognized at birth that is congenital, lymphatic malformations tend to be soft, spongy, non-tender masses. The most common symptoms and lymphatic malformations severity differs depending upon the size and specific location of the malformation. Some lymphatic malformations can be massive or huge Lymphatic malformations can potentially cause functional impairment of nearby structures or organs and disfigurement of affected areas Irrespective of size.

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.  

Gestational Diseases (GTD) may be defined as bunch of rare diseases that develop within the womb throughout an abnormal physiological condition. It happens once when abnormal cells or tumours grow inside the tissues that are square measure shaped following conception that may unremarkably surround the embryo and transform the placenta. Redness is caused by Acute venereal disease which might result in the Fitz-Hugh-Curtis syndrome (perihepatitis that causes higher right quadrant pain). Infection may become chronic, which are characterised by intermittent exacerbations and remissions.

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.

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.

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.

Even though numerous endocrine system illnesses such as diabetes, thyroid, and osteoporosis are among the utmost common and well known medical conditions, some patients who have been referred to an endocrinologist will require treatment for a rare disease. Numbers of these rare diseases are dangerous and lead to myriad sequelae and secondary diseases. Gland-based hormonal imbalances resulting in developmental abnormalities and related complications are among these diseases, weight regulation issues and physical abnormalities and frequent carcinogenic and non-carcinogenic endocrine-related tumour disorders (e.g., multiple endocrine neoplasia, neuroendocrine cancer adrenocortical carcinoma, papillary thyroid carcinoma, primary thyroid lymphoma). Rare endocrine diseases can potentially impact any organ system, however.

A wide range of rare conditions involve the musculoskeletal system. Some, like Duchenne muscular dystrophy, arise from genetic problems in the muscles themselves, while others involve the nerves (e.g., Charcot-Marie-Tooth disease), motor neurons (e.g., amyotrophic lateral sclerosis [ALS]), or the bones (e.g., osteogenesis imperfecta). Problems in other part of the body—such as mitochondrial disease or a metabolic disease like carnitine deficiency can also lead to major problems with these systems. Many individuals are familiar with some of these conditions. Nonetheless, treatment options remain limited although extensive research may soon change that.

Researchers have made dramatic inroads into the study of polygenic and other complex human diseases, due in large part to knowledge of the human genome sequence, the generation of widespread markers of genetic variation, and the development of new technologies that allow investigators to associate disease phenotypes with genetic loci. Although polygenic diseases are more common than single-gene disorders, studies of monogenic diseases provide an invaluable opportunity to learn about underlying molecular mechanisms, thereby contributing a great deal to our understanding of all forms of genetic disease.

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).

Economic difficulties related to the prevention, analysis and treatment of Rare Diseases and production of Orphan Drugs are presented compensating particular attention to the costs of financing treatment, including the issue of its repayment, which is an important and difficult to solve economic problem of the health care system. Cumulative pressures on health care financial plan have led to a rising attention in the use of economic evaluation in reimbursement decisions for Orphan Drugs and other health technologies.

As per the recent researches, the orphan drug market is now opening to display trends seen in traditional pharma markets. The numbers of orphan drug approvals have increased in recent years. Both novel agents and new indications serve as the primary drivers of this recent orphan drug growth. The new business model of orphan drugs could offer a cohesive healthcare resolution that enables pharma companies to develop newer areas of therapeutics, analysis, treatment, monitoring, and patient support. Additionally, the development of orphan drugs is faced with some challenges that are unique to rare diseases. In spite of the challenges, creative Competitive Intelligence (CI) strategies can provide an attentive and improved method for the successful development of orphan drugs.