Patients with CHH usually suffer from cellular immunodeficiency. In the study of 108 Finnish patients with CHH there was detected mild to moderate form of lymphopenia, decreased delayed type of hypersensitivity and impaired responses to phytohaemagglutinin. This leads to susceptibility to and, in some more severe cases, mortality from infections early in childhood. There has also been detected combined immunodeficiency in some patients

Patients with CHH often have increased predispositions to malignancies.

Life expectancy for individuals with hypochondroplasia is normal; the maximum height is about 147 cm or 4.8 ft.

This condition is a consequence of mutations in the PEX7 gene, GNPAT gene (which is located on chromosome 1) and AGPS gene, the condition is acquired in a autosomal recessive manner.

The mechanism of rhizomelic chondrodysplasia punctata in the case of "type 1" of this condition one finds that peroxisome objective is PEX7, in peroxisome assembly.There are 3 pathways that "count on" PEX7 and are:

Achondrogenesis is a number of disorders that are the most severe form of congenital chondrodysplasia (malformation of bones and cartilage). These conditions are characterized by a small body, short limbs, and other skeletal abnormalities. As a result of their serious health problems, infants with achondrogenesis are usually born prematurely, are stillborn, or die shortly after birth from respiratory failure. Some infants, however, have lived for a while with intensive medical support.

Researchers have described at least three forms of achondrogenesis, designated as Achondrogenesis type 1A, achondrogenesis type 1B and achondrogenesis type 2. These types are distinguished by their signs and symptoms, inheritance pattern, and genetic cause. Other types of achondrogenesis may exist, but they have not been characterized or their cause is unknown.

Achondrogenesis type 1A is caused by a defect in the microtubules of the Golgi apparatus. In mice, a nonsense mutation in the thyroid hormone receptor interactor 11 gene (Trip11), which encodes the Golgi microtubule-associated protein 210 (GMAP-210), resulted in defects similar to the human disease. When their DNA was sequenced, human patients with achondrogenesis type 1A also had loss-of-function mutations in GMAP-210. GMAP-210 moves proteins from the endoplasmic reticulum to the Golgi apparatus. Because of the defect, GMAP-210 is not able to move the proteins, and they remain in the endoplasmic reticulum, which swells up. The loss of Golgi apparatus function affects some cells, such as those responsible for forming bone and cartilage, more than others.

Achondrogenesis type 1B is caused by a similar mutation in SLC26A2, which encodes a sulfate transporter.

Chondrodysplasia punctata is a clinically and genetically diverse group of rare diseases, first described by Erich Conradi (1882–1968), that share the features of stippled epiphyses and skeletal changes.

Types include:

- Rhizomelic chondrodysplasia punctata , ,

- X-linked recessive chondrodysplasia punctata

- Conradi-Hünermann syndrome

- Autosomal dominant chondrodysplasia punctata

Cartilage–hair hypoplasia (CHH), also known as McKusick type metaphyseal chondrodysplasia, is a rare genetic disorder. It is a highly pleiotropic disorder that clinically manifests by form of short-limbed dwarfism due to skeletal dysplasia, variable level of immunodeficiency and predisposition to malignancies in some cases. It was first reported in 1965 by McKusick et al. Actor Verne Troyer is affected with this form of dwarfism, as was actor Billy Barty, who was renowned for saying "The name of my condition is Cartilage Hair Syndrome Hypoplasia, but you can just call me Billy."

X-linked recessive chondrodysplasia punctata is a type of chondrodysplasia punctata that can involve the skin, hair, and cause short stature with skeletal abnormalities, cataracts, and deafness.

This condition is also known as arylsulfatase E deficiency, CDPX1, and X-linked recessive chondrodysplasia punctata 1. The syndrome rarely affects females, but they can be carriers of the recessive allele. Although the exact number of people diagnosed with CDPX1 is unknown, it was estimated that 1 in 500,000 have CDPX1 in varying severity. This condition is not linked to a specific ethnicity. The mutation that leads to a deficiency in arylsulfatase E. (ARSE) occurs in the coding region of the gene.Absence of stippling, deposits of calcium, of bones and cartilage, shown on x-ray, does not rule out chondrodysplasia punctata or a normal chondrodysplasia punctata 1 (CDPX1) gene without mutation. Stippling of the bones and cartilage is rarely seen after childhood. Phalangeal abnormalities are important clinical features to look for once the stippling is no longer visible. Other, more severe, clinical features include respiratory abnormalities, hearing loss, cervical spine abnormalities, delayed cognitive development, ophthalmologic abnormalities, cardiac abnormalities, gastroesophageal reflux, and feeding difficulties. CDPX1 actually has a spectrum of severity; different mutations within the CDPX1 gene have different effects on the catalytic activity of the ARSE protein. The mutations vary between missense, nonsense, insertions, and deletions.

In terms of cause this disorder is transmitted as an autosomal dominant trait affecting the "FGFR3" gene on chromosome 4p16.3, there is currently no cure for this condition.

Schmid metaphyseal chondrodysplasia is a type of chondrodysplasia associated with a deficiency of collagen, type X, alpha 1.

Unlike other "rickets syndromes", affected individuals have normal serum calcium, phosphorus, and urinary amino acid levels. Long bones are short and curved, with widened growth plates and metaphyses.

It is named for the German researcher F. Schmid, who characterized it in 1949.

CDPX1 activity may be inhibited by warfarin because it is believed that ARSE has enzymatic activity in a vitamin K producing biochemical pathway. Vitamin K is also needed for controlling binding of calcium to bone and other tissues within the body.

Treatment is symptomatic, often addressing indicators associated with peripheral pulmonary artery stenosis. Laryngotracheal calcification resulting in dyspnea and forceful breathing can be treated with bronchodilators including the short and long-acting β2-agonists, and various anticholinergics. Prognosis is good, yet life expectancy depends on the severity and extent of diffuse pulmonary and arterial calcification.

The mutated gene responsible for the disorder is the FGFR3 gene, more specifically; a Lys650Met missense mutation of the FGFR3 gene is what causes SADDAN. This gene codes for the instructions of a protein that is integral in the development and maintenance of bone and brain tissue. Mutations of this gene cause the protein to be overly active, causing many characteristics of this disorder.

SADDAN is an autosomal dominant genetic disorder. Autosomal means that the gene responsible for the mutation and disorder is found on a non-sex chromosome and that either the mother or father can pass on the gene, while dominant means that only one copy of the gene is required for the individual to have the disorder.

Fortunately the disorder is very rare and has only been described in a few number of cases worldwide. While the disorder can be genetically inherited, no instances of inheritance have been recorded as of yet. Rather, of the few cases documented, the individual affected by the disorder is affected as a product of a random mutation, also called a de novo mutation, of the FGFR3 gene only, not by inheritance of the mutated gene.

Severe achondroplasia with developmental delay and acanthosis nigricans (SADDAN), is a very rare genetic disorder. This disorder is one that affects bone growth and is characterized by skeletal, brain, and skin abnormalities. Those affected by the disorder are severely short in height and commonly possess shorter arms and legs. In addition, the bones of the legs are often bowed and the affected have smaller chests with shorter rib bones, along with curved collarbones. Other symptoms of the disorder include broad fingers and extra folds of skin on the arms and legs. Developmentally, many individuals who suffer from the disorder show a higher level in delays and disability. Seizures are also common due to structural abnormalities of the brain. Those affected may also suffer with apnea, the slowing or loss of breath for short periods of time.

Many of the features of SADDAN are similar to those seen in other skeletal disorders, specifically achondroplasia and thanatophoric dysplasia.

Achondroplasia is a form of short-limbed dwarfism. This type of dwarfism is caused by the inability of the cartilage of the skeleton to ossify and turn to bone. Acanthosis nigricans is a skin condition in which areas of the skin is of a dark and velvety discoloration, often seen in the body folds and creases such as the armpits, groin, and neck. Within those affected by SADDAN, acanthosis nigricans develops early on, usually in infancy or early childhood.

Achondroplasia is caused by a mutation in fibroblast growth factor receptor 3 (FGFR3). In normal development FGFR3 has a negative regulatory effect on bone growth. In achondroplasia, the mutated form of the receptor is constitutively active and this leads to severely shortened bones. The effect is genetically dominant, with one mutant copy of the FGFR3 gene being sufficient to cause achondroplasia, while two copies of the mutant gene are invariably fatal (recessive lethal) before or shortly after birth (known as a lethal allele). A person with achondroplasia thus has a 50% chance of passing dwarfism to each of their offspring. People with achondroplasia can be born to parents that do not have the condition due to spontaneous mutation.

Studies have demonstrated that new gene mutations for achondroplasia are exclusively inherited from the father and occur during spermatogenesis; it is theorized that oogenesis has some regulatory mechanism that prevents the mutation from being passed on in females.

There are two other syndromes with a genetic basis similar to achondroplasia: hypochondroplasia and thanatophoric dysplasia.

Achondroplasia is a genetic disorder that results in dwarfism. The arms and legs are short, while the trunk is typically of normal length. Those affected have an average adult height of for males and for females. Other features include an enlarged head and prominent forehead. Intelligence is generally normal.

Achondroplasia is due to a mutation in the FGFR3 gene. In about 80% of cases this occurs as a new mutation during early development. In the other cases it is inherited from one's parents in an autosomal dominant manner. Those with two effected genes do not typically survive. Diagnosis is generally based on symptoms, but may be supported by genetic testing if uncertain.

Treatments may include support groups and growth hormone therapy. Efforts to treat or prevent complications such as obesity, hydrocephalus, obstructive sleep apnea, middle ear infections, or spinal stenosis may be required. Life expectancy of those affected is about 10 years less than average. The condition affects about 1 in 27,500 people. Rates are higher in Denmark and Latin America. The shortest known adults with the condition is Jyoti Amge at .

Muenke syndrome is caused by a specific gene mutation in the FGFR3 gene. The mutation arises randomly; there is no full understanding for what causes this mutation. This mutation causes the FGFR3 protein to be overly active; it interferes with normal bone growth, and allows skull bones to fuse prematurely. There is no connection between anything mother did (or did not do) to activate the syndrome. If neither of the parents have Muenke syndrome, chances of having another child with the syndrome are minimal.

This condition is inherited in an autosomal dominant pattern. This means if a parent has Muenke syndrome, every newborn has a 50% chance of inheriting the syndrome.

Collagen, type II, alpha 1 (primary osteoarthritis, spondyloepiphyseal dysplasia, congenital), also known as COL2A1, is a human gene that provides instructions for the production of the pro-alpha1(II) chain of type II collagen.

Treatment can involve operations to lengthen the leg bones, which involves many visits to the hospital. Other symptoms can be treated with medicine or surgery. Most female patients with the syndrome can live a long and normal life, while males have only survived in rare cases.

Keutel syndrome (KS) is a rare autosomal recessive genetic disorder characterized by abnormal diffuse cartilage calcification, hypoplasia of the mid-face, peripheral pulmonary stenosis, hearing loss, short distal phalanges (tips) of the fingers and mild mental retardation. Individuals with KS often present with peripheral pulmonary stenosis, brachytelephalangism, sloping forehead, midface hypoplasia, and receding chin. It is associated with abnormalities in the gene coding for matrix gla protein (MGP). Being an autosomal recessive disorder, it may be inherited from two unaffected, abnormal MGP-carrying parents. Thus, people who inherit two affected MGP genes will likely inherit KS.

It was first identified in 1972 as a novel rare genetic disorder sharing similar symptoms with chondrodysplasia punctata. Multiple forms of chondrodysplasia punctata share symptoms consistent with KS including abnormal cartilage calcification, forceful respiration, brachytelephalangism, hypotonia, psychomotor delay, and conductive deafness, yet peripheral pulmonary stenosis remains unique to KS.

No chromosomal abnormalities are reported in affected individuals, suggesting that familial consanguinity relates to the autosomal recessive mode of inheritance. Also, despite largely abnormal calcification of regions including the larynx, tracheobronchial tree, nose, pinna (anatomy), and epiglottis, patients exhibit normal serum calcium and phosphate levels.

Chondrodysplasia Blomstrand (also known as Blomstrand's lethal chondrodysplasia) is a rare disorder caused by mutation of the parathyroid hormone receptor resulting in the absence of a functioning PTHR1. It results in ossification of the endocrine system and intermembraneous tissues and advanced skeletal maturation

Till date about 18 cases of Spondylocostal dysostosis have been reported in literature.

Muenke syndrome is inherited in an autosomal dominant pattern. In some cases, an affected person inherits the mutation from one affected parent. If a patient is shown to have Muenke, they have a 50/50 chance of passing it on to their children. Not all cases of Muenke however is obvious. Other cases may result from new mutations in the gene. These cases occur in people with no history of the disorder in their family.

A single mutation in the FGFR3 gene cause this syndrome. The FGFR3 gene provides instructions for making a protein that is involved in the development and maintenance of bone and brain tissue. This mutation causes the FGFR3 protein to be overly active, which interferes with normal bone growth and allows the bones of the skull to fuse before they should.

As stated by researchers at the University of Washington, Muenke syndrome is inherited in an autosomal dominant manner with incomplete penetrance and variable expressivity.” Prenatal diagnosis for pregnancies at increased risk is possible if the defining mutation has been identified in the family (Agochukwu et.al. 2006). According to the article "Craniosynostosis: Molecular Genetics," penetrance is higher in females (87%) than in males (76%). Muenke syndrome is estimated to account for 25%-30% of all genetic causes of craniosynostosis according to the Journal of Anatomy.

Conradi–Hünermann syndrome is a form of chondrodysplasia punctata, a group of rare genetic disorders of skeletal development involving abnormal accumulations of calcium salts within the growing ends of long bones. Conradi–Hünermann syndrome is commonly associated with mild to moderate growth deficiency, disproportionate shortening of long bones, particularly those of the upper arms and the thigh bones, short stature, and/or curvature of the spine. In rare cases, intellectual disability may also be present. While evidence suggests that Conradi–Hünermann syndrome predominantly occurs in females and is usually inherited as an X-linked dominant trait, rare cases in which males were affected have also been reported.

The genetics of Conradi–Hünermann syndrome has perplexed medical geneticists, pediatricians and dermatologists for some time, but a number of perplexing features of the genetics of the syndrome have now been resolved, including the fact that the disease is caused by mutations in a gene, and these mutations are simple substitutions, deletions or insertions and are therefore not "unstable". Scientists are still trying to understand exactly where the mutation occurs so that they can correct it.

Weissenbacher-Zweymüller syndrome affects males and females in the same numbers. About 30 cases have been reported in medical literature. This disorder can be underdiagnosed causing no true frequency in the population. Only 30 cases have been reported in medical literature.