Paget's disease may be caused by a slow virus infection (i.e., paramyxoviridae) present for many years before symptoms appear. Associated viral infections include respiratory syncytial virus, canine distemper virus, and the measles virus. However, recent evidence has cast some doubt upon the measles association. Laboratory contamination may have played a role in past studies linking paramyxovirus (e.g. measles) to Paget's disease.

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.

The disease is progressive and slowly worsens with time, although people may remain minimally symptomatic. Treatment is aimed at controlling symptoms, but there is no cure. Any bone or bones can be affected, but Paget's disease occurs most frequently in the spine, skull, pelvis, femur, and lower legs.

Osteogenic sarcoma, a form of bone cancer, is a rare complication of Paget's disease occurring in less than one percent of those affected. The development of osteosarcoma may be suggested by the sudden onset or worsening pain.

The various types of osteopetrosis are caused by genetic changes (mutations) in one of at least ten genes. There is nothing a parent can do before, during or after a pregnancy to cause osteopetrosis in a child.

The genes associated with osteopetrosis are involved in the development and/or function of osteoclasts, cells that break down bone tissue when old bone is being replaced by new bone (bone remodeling). This process is necessary to keep bones strong and healthy. Mutations in these genes can lead to abnormal osteoclasts, or having too few osteoclasts. If this happens, old bone cannot be broken down as new bone is formed, so bones become too dense and prone to breaking.

- Mutations in the CLCN7 gene cause most cases of autosomal dominant osteopetrosis, 10-15% of cases of autosomal recessive osteopetrosis (the most severe form), and all known cases of intermediate autosomal osteopetrosis.

- Mutations in the TCIRG1 gene cause about 50% of cases of autosomal recessive osteopetrosis.

- Mutations in the IKBKG gene cause X-linked osteopetrosis.

- Mutations in other genes are less common causes of osteopetrosis.

- In about 30% percent of affected people, the cause is unknown.

Normally, bone growth is a balance between osteoblasts (cells that create bone tissue) and osteoclasts (cells that destroy bone tissue). Sufferers of osteopetrosis have a deficiency of osteoclasts, meaning too little bone is being resorbed, resulting in too much bone being created.

More than 1 in 2 people with OI also have dentinogenesis imperfecta (DI) - a congenital disorder of formation of dentine. Dental treatment may pose as a challenge as a result of the various deformities, skeletal and dental, due to OI. Children with OI should go for a dental check-up as soon as their teeth erupt, this may minimize tooth structure loss as a result of abnormal dentine, and they should be monitored regularly to preserve their teeth and oral health.

Osteogenesis imperfecta is a rare condition in which bones break easily. There are multiple genetic mutations in different genes for collagen that may result in this condition. It can be treated with some drugs to promote bone growth, by surgically implanting metal rods in long bones to strengthen them, and through physical therapy and medical devices to improve mobility.

Osteoporosis is due to causal factors like atrophy of disuse and gonadal deficiency. Hence osteoporosis is common in post menopausal women and in men above 50 yrs. Hypercorticism may also be causal factor, as osteoporosis may be seen as a feature of Cushing's syndrome.

Osteogenesis imperfecta (OI), also known as brittle bone disease, is a group of genetic disorders that mainly affect the bones. It results in bones that break easily. The severity may be mild to severe. Other symptoms may include a blue tinge to the whites of the eye, short height, loose joints, hearing loss, breathing problems, and problems with the teeth. Complications may include cervical artery dissection and aortic dissection.

The underlying mechanism is usually a problem with connective tissue due to a lack of type I collagen. This occurs in more than 90% of cases due to mutations in the "COL1A1" or "COL1A2" genes. These genetic problems are often inherited from a person's parents in an autosomal dominant manner or occur via a new mutation. There are eight types with type I being the least severe and type II the most severe. Diagnosis is often based on symptoms and may be confirmed by collagen or DNA testing.

There is no cure. Maintaining a healthy lifestyle by exercising and avoiding smoking can help prevent fractures. Treatment may include care of broken bones, pain medication, physical therapy, braces or wheelchairs, and surgery. A type of surgery that puts metal rods through long bones may be done to strengthen them. Tentative evidence supports the use of medications of the bisphosphonate type.

OI affects about one in 15,000 people. Outcomes depend on the type of disease. Most people, however, have good outcomes. The condition has been described since ancient history. The term "osteogenesis imperfecta" came into use in 1895 and means imperfect bone formation.

Fibrochondrogenesis is quite rare. A 1996 study from Spain determined a national minimal prevalence for the disorder at 8 cases out of 1,158,067 live births.

A United Arab Emirates (UAE) University report, from early 2003, evaluated the results of a 5-year study on the occurrence of a broad range of osteochondrodysplasias. Out of 38,048 newborns in Al Ain, over the course of the study period, fibrochondrogenesis was found to be the most common of the recessive forms of osteochondrodysplasia, with a prevalence ratio of 1.05:10,000 births.

While these results represented the most common occurrence within the group studied, they do not dispute the rarity of fibrochondrogenesis. The study also included the high rate of consanguinous marriages as a prevailing factor for these disorders, as well as the extremely low rate of diagnosis-related pregnancy terminations throughout the region.

Metabolic bone disease is an umbrella term referring to abnormalities of bones caused by a broad spectrum of disorders.

Most commonly these disorders are caused by abnormalities of minerals such as calcium, phosphorus, magnesium or vitamin D leading to dramatic clinical disorders that are commonly reversible once the underlying defect has been treated. These disorders are to be differentiated from a larger group of genetic bone disorders where there is a defect in a specific signaling system or cell type that causes the bone disorder. There may be overlap. For example, genetic or hereditary hypophosphatemia may cause the metabolic bone disorder osteomalacia. Although there is currently no treatment for the genetic condition, replacement of phosphate often corrects or improves the metabolic bone disorder.

"Achondroplasia" is a type of autosomal dominant genetic disorder that is the most common cause of dwarfism. Achondroplastic dwarfs have short stature, with an average adult height of 131 cm (4 feet, 3 inches) for males and 123 cm (4 feet, 0 inches) for females.

The prevalence is approximately 1 in 25,000 births.

Some parents of children with MHE have observed autism-like social problems in their children. To explore those observations more deeply, a 2012 study by the Sanford-Burnham Medical Research Institute used a mouse model of MHE to observe cognitive function. The findings indicated that the mutant mice endorsed three autistic characteristics: social impairment, impairments in ultrasonic vocalization, and repetitive behavior.

PDP occurs more frequently in men than in women (ratio around 7:1). Moreover, men suffer from more severe symptoms (see table 1). African American people are affected to a higher extent.

Table 1. Distribution of different forms of PDP among 201 reported affected men and women (167 men and 34 women).

HME is an autosomal dominant hereditary disorder. This means that a patient with HME has a 50% chance of transmitting this disorder to his or her children. Most individuals with HME have a parent who also has the condition, however, approximately 10% -20% of individuals with HME have the condition as a result of a spontaneous mutation and are thus the first person in their family to be affected.

HME has thus far been linked with mutations in three genes.

- EXT1 which maps to chromosome 8q24.1

- EXT2 which maps to 11p13

- EXT3 which maps to the short arm of Chromosome 19 (though its exact location has yet to be precisely determined)

Mutations in these genes typically lead to the synthesis of a truncated EXT protein which does not function normally. It is known that EXT proteins are important enzymes in the synthesis of heparan sulfate; however the exact mechanism by which altered synthesis of heparan sulfate that could lead to the abnormal bone growth associated with HME is unclear. It is thought that normal chondrocyte proliferation and differentiation may be affected, leading to abnormal bone growth. Since the HME genes are involved in the synthesis of a glycan (heparan sulfate), HME may be considered a congenital disorder of glycosylation according to the new CDG nomenclature suggested in 2009.

For individuals with HME who are considering starting a family, preimplantation genetic testing and prenatal diagnosis are available to determine if their unborn child has inherited the disease. HME has a 96% penetrance, which means that if the affected gene is indeed transmitted to a child, the child will have a 96% of actually manifesting the disease, and 4% chance of having the disease but never manifesting it. It should be noted that the 96% penetrance figure comes from one study. Other studies have observed both incomplete and variable penetrance but without calculating the % penetrance, e.g. In both the aforementioned studies the symptomless individuals carrying the faulty gene were predominantly female, leading to speculation that incomplete penetrance is more likely to be exhibited in females. Indeed, other work has shown that boys/men tend to have worse disease than females, as well as that the number of exostoses in affected members of the same family can vary greatly. It is also possible for females to be severely affected.

Symptoms are more likely to be severe if the mutation is on the "ext1" gene rather than "ext2" or "ext3"; "ext1" is also the most commonly affected gene in patients of this disorder.

The only effective line of treatment for malignant infantile osteopetrosis is hematopoietic stem cell transplantation. It has been shown to provide long-term disease-free periods for a significant percentage of those treated; can impact both hematologic and skeletal abnormalities; and has been used successfully to reverse the associated skeletal abnormalities.

Radiographs of at least one case with malignant infantile osteopetrosis have demonstrated bone remodeling and recanalization of medullar canals following hematopoietic stem cell transplantation. This favorable radiographic response could be expected within one year following the procedure - nevertheless, primary graft failure can prove fatal.

Malignant infantile osteopetrosis, also known as infantile autosomal recessive osteopetrosis or simply infantile osteopetrosis is a rare osteosclerosing type of skeletal dysplasia that typically presents in infancy and is characterized by a unique radiographic appearance of generalized hyperostosis - excessive growth of bone.

The generalized increase in bone density has a special predilection to involve the medullary portion with relative sparing of the cortices. Obliteration of bone marrow spaces and subsequent depression of the cellular function can result in serious hematologic complications. Optic atrophy and cranial nerve damage secondary to bony expansion can result in marked morbidity. The prognosis is extremely poor in untreated cases. Plain radiography provides the key information to the diagnosis. Clinical and radiologic correlations are also fundamental to the diagnostic process, with additional gene testing being confirmatory.

Fibrochondrogenesis is inherited in an autosomal recessive pattern. This means that the defective gene responsible for the disorder is located on an autosome, and two copies of the gene — one copy inherited from each parent — are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder each carry one copy of the defective gene, but usually do not experience any signs or symptoms of the disorder. Currently, no specific genetic mutation has been established as the cause of fibrochondrogenesis.

Omphalocele is a congenital feature where the abdominal wall has an opening, partially exposing the abdominal viscera (typically, the organs of the gastrointestinal tract). Fibrochondrogenesis is believed to be related to omphalocele

type III, suggesting a possible genetic association between the two disorders.

Because this genetic anomaly is genetically linked, genetic counseling may be the only way to decrease occurrences of Cherubism. The lack of severe symptoms in the parents may be the cause of failure in recognizing the disorder. The optimal time to be tested for mutations is prior to having children. The disorder results from a genetic mutation, and this gene has been found to spontaneously mutate. Therefore, there may be no prevention techniques available.

PDP is a rare genetic disease. At least 204 cases of PDP have been reported. The precise incidence and prevalence of PDP are still unknown. A prevalence of 0.16% was suggested by Jajic et Jajic.

All clinical sub-types of hypophosphatasia have been traced to genetic mutations in the gene encoding TNSALP, which is localized on chromosome 1p36.1-34 in humans (ALPL; OMIM#171760). Approximately 204 distinct mutations have been described in the TNSALP gene. An up-to-date list of mutations is available online at The Tissue Nonspecific Alkaline Phosphatase Gene Mutations Database. About 80% of the mutations are missense mutations. The number and diversity of mutations results in highly variable phenotypic expression, and there appears to be a correlation between genotype and phenotype in hypophosphatasia”. Mutation analysis is possible and available in 3 laboratories.

Cherubism is a rare genetic disorder that causes prominence in the lower portion in the face. The name is derived from the temporary chubby-cheeked resemblance to putti, often confused with cherubs, in Renaissance paintings.

Perinatal and infantile hypophosphatasia are inherited as autosomal recessive traits with homozygosity or compound heterozygosity for two defective TNSALP alleles. The mode of inheritance for childhood, adult, and odonto forms of hypophosphatasia can be either autosomal dominant or recessive. Autosomal transmission accounts for the fact that the disease affects males and females with equal frequency. Genetic counseling is complicated by the disease’s variable inheritance pattern, and by incomplete penetration of the trait.

Hypophosphatasia is a rare disease that has been reported worldwide and appears to affect individuals of all ethnicities. The prevalence of severe hypophosphatasia is estimated to be 1:100,000 in a population of largely Anglo-Saxon origin. The frequency of mild hypophosphatasia is more challenging to assess because the symptoms may escape notice or be misdiagnosed. The highest incidence of hypophosphatasia has been reported in the Mennonite population in Manitoba, Canada where one in every 25 individuals are considered carriers and one in every 2,500 newborns exhibits severe disease. Hypophosphatasia is considered particularly rare in people of African ancestry in the U.S.

Trevor disease, also known as Fairbank's disease and Trevor's disease, is a congenital bone developmental disorder. There is 1 case per million population. The condition is three times more common in males than in females.

Most reported cases of DEH in the literature have been treated surgically, with excision of the mass, as well as by the correction

of any deformity, while preserving the integrity of the affected joint as much as possible.

Genetically, there is a postzygotic mutation (spontaneous mutation) of the gene GNAS, on the long (q) arm of chromosome 20 at position 13.3, which is involved in G-protein signaling. This mutation, which occurs only in the mosaic state, leads to constitutive receptor signaling and inappropriate production of excess cAMP.

The mutation that causes McCune–Albright syndrome arises very early during embryogenesis. It is not passed down from parent to child. There are no known risk factors for acquiring McCune–Albright syndrome, and no exposures during pregnancy that are known to either cause or prevent the mutation from occurring.