Diagnosis may be suspected on the basis of the clinical and radiologic findings, and can supported by molecular analysis of the SHOX, SHOXY and PAR1 genes.

May also be suspected by ultrasound during the second trimester of gestation.

Exact diagnosis remains widely built on precise history taking, with the characteristic clinical and radiographic skeletal features. Genetic diagnosis is based on DNA sequencing. Because plasma COMP levels are significantly reduced in patients with COMP mutations, such as pseudoachondroplasia, measuring plasma COMP levels has become a reliable means of diagnosing this and pathopysiologically similar disorders.

Physical examination shows that the lower legs angle inward. An x-ray of the knee and the lower leg confirms the diagnosis.

There are several ways to determine if a child has chondrodystrophy, including parent testing and x-rays. If the fetus is suspected of having chondrodystrophy, the parents can be tested to find out if the fetus in fact does have the disease. It is not until the baby is born that a diagnosis can be declared. The diagnosis is declared with the help of several x-rays and charted bone growth patterns. Once the child is diagnosed the parents have to monitor the children because of several different factors. As the child gets older, hearing, eyesight and motor skills may be defective. Also, breathing (apnea) and weight problems (obesity) may occur. Structurally, scoliosis, bowed legs (genu varum), and arthritis may result.

The diagnosis of this condition can be done via x-rays (with lack of normal distance L1 to L5), and additionally genetic testing is available to ascertain hypochondroplasia However, the physical characteristics(physical finding) is one of the most important in determining the condition.

The decision to treat is based on a belief that the child will be disabled by being extremely short as an adult, so that the risks of treatment (including sudden death) will outweigh the risks of not treating the symptom of short stature. Although short children commonly report being teased about their height, most adults who are very short are not physically or psychologically disabled by their height. However, there is some evidence to suggest that there is an inverse linear relationship with height and with risk of suicide.

Treatment is expensive and requires many years of injections with human growth hormones. The result depends on the cause, but is typically an increase in final height of about taller than predicted. Thus, treatment takes a child who is expected to be much shorter than a typical adult and produces an adult who is still obviously shorter than average. For example, several years of successful treatment in a girl who is predicted to be as an adult may result in her being instead.

Increasing final height in children with short stature may be beneficial and could enhance health-related quality of life outcomes, barring troublesome side effects and excessive cost of treatments.

Accurate assessment of plain radiographic findings remains an important contributor to diagnosis of pseudoachondroplasia. It is noteworthy that vertebral radiographic abnormalities tend to resolve over time. Epiphyseal abnormalities tend to run a progressive course. Patients usually suffer early-onset arthritis of hips and knees. Many unique skeletal radiographic abnormalities of patients with pseudoachondroplasia have been reported in the literature.

- Together with rhizomelic limb shortening, the presence of epiphyseal-metaphyseal changes of the long bones is a distinctive radiologic feature of pseudoachondroplasia.

- Hypoplastic capital femoral epiphyses, broad short femoral necks, coxa vara, horizontality of acetabular roof and delayed eruption of secondary ossification center of os pubis and greater trochanter.

- Dysplastic/hypoplastic epiphyses especially of shoulders and around the knees.

- Metaphyseal broadening, irregularity and metaphyseal line of ossification. These abnormalities that are typically encountered in proximal humerus and around the knees are collectively known as “rachitic-like changes”.

- Radiographic lesions of the appendicular skeleton are typically bilateral and symmetric.

- Oval shaped vertebrae with anterior beak originating and platyspondyly demonstrated on lateral radiographs of the spine.

- Normal widening of the interpedicular distances caudally demonstrated on anteroposterior radiographs of the dorsolumbar region. This is an important differentiating feature between pseudoachondroplasia and achondroplasia.

- Odontoid hypoplasia may occur resulting in cervical instability.

Ultrasound remains as one of the only effective ways of prenatally diagnosing Larsen syndrome. Prenatal diagnosis is extremely important, as it can help families prepare for the arrival of an infant with several defects. Ultrasound can capture prenatal images of multiple joint dislocations, abnormal positioning of legs and knees, depressed nasal bridge, prominent forehead, and club feet. These symptoms are all associated with Larsen syndrome, so they can be used to confirm that a fetus has the disorder.

There is no known cure. In selected patients orthopaedic surgery may be helpful to try to gain some functionality of severely impaired joints.

A clinical diagnosis of SCS can be verified by testing the TWIST1 gene (only gene in which mutations are known to cause SCS) for mutations using DNA analysis, such as sequence analysis, deletion/duplication analysis, and cytogenetics/ FISH analysis. Sequence analysis of exon 1 (TWIST1 coding region) provides a good method for detecting the frequency of mutations in the TWIST1 gene. These mutations include nonsense, missense, splice site mutation, and intragenic deletions/insertions. Deletion/duplication analysis identifies mutations in the TWIST1 gene that are not readily detected by sequence analysis. Common methods include PCR, multiplex ligation-dependent probe amplification (MLPA), and chromosomal microarray (CMA). Cytogenetic/FISH analysis attaches fluorescently labels DNA markers to a denatured chromosome and is then examined under fluorescent lighting, which reveals mutations caused by translocations or inversions involving 7p21. Occasionally, individuals with SCS have a chromosome translocation, inversion, or ring chromosome 7 involving 7p21 resulting in atypical findings, such as, increased developmental delay. Individuals with SCS, typically have normal brain functioning and rarely have mental impairments. For this reason, if an individual has both SCS and mental retardation, then they should have their TWIST1 gene screened more carefully because this is not a normal trait of SCS. Cytogenetic testing and direct gene testing can also be used to study gene/chromosome defects. Cytogenetic testing is the study of chromosomes to detect gains or losses of chromosomes or chromosome segments using fluorescent in situ hybridization (FISH) and/or comparative genomic hybridization (CGH). Direct gene testing uses blood, hair, skin, amniotic fluid, or other tissues in order to find genetic disorders. Direct gene testing can determine whether an individual has SCS by testing the individual's blood for mutations in the TWIST1 gene.

Depending on the severity of the deformities, the treatment may include the amputation of the foot or part of the leg, lengthening of the femur, extension prosthesis, or custom shoe lifts. Amputation usually requires the use of prosthesis. Another alternative is a rotationplasty procedure, also known as Van Ness surgery. In this situation the foot and ankle are surgically removed, then attached to the femur. This creates a functional "knee joint". This allows the patient to be fit with a below knee prosthesis vs a traditional above knee prosthesis.

In less severe cases, the use of an Ilizarov apparatus can be successful in conjunction with hip and knee surgeries (depending on the status of the femoral head/kneecap) to extend the femur length to normal ranges. This method of treatment can be problematic in that the Ilizarov might need to be applied both during early childhood (to keep the femur from being extremely short at the onset of growth) and after puberty (to match leg lengths after growth has ended). The clear benefit of this approach, however, is that no prosthetics are needed and at the conclusion of surgical procedures the patient will not be biologically or anatomically different from a person born without PFFD.

Up until recently, experts frequently disagreed on whether a patient had SCS, Crouzon syndrome, isolated craniosynostosis, or some other disease because the symptoms are so closely related, they literally had no way of differentiating between all of them. However, we now have direct gene testing, which allows for a more definitive diagnosis because it allows them to be differentiated from each other based on which gene is mutated in each condition. The following is a list of conditions commonly confused/misdiagnosed for SCS, some of their symptoms, and which mutated gene each contains:

Children who develop severe bowing before the age of 3 may be treated with knee ankle foot orthoses. However, bracing may fail, or bowing may not be detected until the child is older. In some cases, surgery may be performed. Surgery may involve cutting the shin bone (tibia) to realign it, and sometimes lengthen it as well.

Other times, the growth of just the outer half of the tibia can be surgically restricted to allow the child’s natural growth to reverse the bowing process. This second, much smaller surgery is most effective in children with less severe bowing and significant growth remaining.

Return to normal function and cosmetic appearance is expected if the knee can be properly aligned.

The cost of treatment depends on the amount of growth hormone given, which in turn depends on the child's weight and age. One year's worth of drugs normally costs about US $20,000 for a small child and over $50,000 for a teenager. These drugs are normally taken for five or more years.

Even though clinical diagnostic criteria have not been 100 percent defined for genitopatellar syndrome, the researchers stated that the certain physical features could relate to KAT6B mutation and result in the molecular genetic testing. The researchers stated that the Individuals with two major features or one major feature and two minor features are likely to have a KAT6B mutation.

To diagnose the Genitopatellar Syndrome, there are multiple ways to evaluate.

Medical genetics consultation

- Evaluation by developmental specialist

- Feeding evaluation

- Baseline hearing evaluation

- Thyroid function tests

- Evaluation of males for cryptorchidism

- Orthopedic evaluation if contractures are present or feet/ankles are malpositioned

- Hip radiographs to evaluate for femoral head dislocation

- Renal ultrasound examination for hydronephrosis and cysts

- Echocardiogram for congenital heart defects

- Evaluation for laryngomalacia if respiratory issues are present

- Evaluation by gastroenterologist as needed, particularly if bowel malrotation is suspected

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

The cause of PFFD is uncertain. Two hypotheses have been advanced. The theory of sclerotome subtraction posits injury to neural crest cells that are the precursors to sensory nerves at the level of L4 and L5. Histologic studies of a fetus with unilateral PFFD have prompted an alternative hypothesis that PFFD is caused by a defect in maturation of chondrocytes (cartilage cells) at the growth plate. In either hypothesis, the agent causing the injury is usually not known. Thalidomide is known to cause PFFD when the mother is exposed to it in the fifth or sixth week of pregnancy, and it is speculated that exposure to other toxins during pregnancy may also be a cause. Other etiologies that have been suggested, but not proven, include anoxia, ischemia, radiation, infection, hormones, and mechanical force. PFFD occurs sporadically, and does not appear to be hereditary.

Fibular hemimelia or longitudinal fibular deficiency is "the congenital absence of the fibula and it is the most common congenital absence of long bone of the extremities." It is the shortening of the fibula at birth, or the complete lack thereof. In humans, the disorder can be noted by ultrasound in utero to prepare for amputation after birth or complex bone lengthening surgery. The amputation usually takes place at six months with removal of portions of the legs to prepare them for prosthetic use. The other treatments which include repeated corrective osteotomies and leg-lengthening surgery (Ilizarov apparatus) are costly and associated with residual deformity.

Treatment for Larsen syndrome varies according to the symptoms of the individual. Orthopedic surgery can be performed to correct the serious joint defects associated with Larsen syndrome. Reconstructive surgery can be used to treat the facial abnormalities. Cervical kyphosis can be very dangerous to an individual because it can cause the vertebrae to disturb the spinal cord. Posterior cervical arthrodesis has been performed on patients with cervical kyphosis, and the results have been successful Propranolol has been used to treat some of the cardiac defects associated with Marfan's syndrome, so the drug also has been suggested to treat cardiac defects associated with Larsen syndrome.

To treat the trigonocephaly, expanding the distance between orbits using springs seems to work. It allows enough space for the brain to grow and it creates a normal horizontal axis of the orbits and supraorbital bar. The endoscopic surgery started to become popular since the early 90's, but it has some technical limitations (only strip cranictomy is possible). There have been few attempts to go beyond the limits.

Aesthetic outcomes of metopic surgery have been good. Surgery does not have a perfect outcome because there will most likely be minor irregularities. Sometimes reoperations are needed for the severe cases. Trying to hollow out the temporal, and the hypoterlorism are very hard to correct. The hypotelorism usually stays not corrected and in order to correct the temporal hollowing, a second operation is most likely needed.

The cause of fibular hemimelia is unclear. Purportedly, there have been some incidents of genetic distribution in a family; however, this does not account for all cases. Maternal viral infections, embryonic trauma, teratogenic environmental exposures or vascular dysgenesis (failure of the embryo to form a satisfactory blood supply) between four and seven weeks gestation are considered possible causes.

In an experimental mouse model, change in the expression of a homeobox gene led to similar, but bilateral, fibular defects.

There is no treatment at this time to promote bone growth in chondrodystrophy patients. Certain types of growth hormone seem to increase the rate of growth during the first year of life/treatment, but have no substantial effect in adult patients. Only a few surgical centers in the world perform, experimentally, leg and arm lengthening procedures. Most common therapies are found in seeking help from: family physicians, pediatrics, internists, endocrinologists, geneticists, orthopedists and neurologists.

There are no treatment to return to its normal functions. However, there are treatments for the different symptoms.

For the Developmental symptoms, Educational intervention and speech therapy beginning in infancy could help to reduce the high risk for motor, cognitive, speech, and language delay

For theSkeletal features, referral to an orthopedist for consideration of surgical release of contractures. In addition,early referral to physical therapy could help increase joint mobility.

Lastly, Thyroid hormone replacement could help out the thyroid dysfunction

A diagnosis can be made by an evaluation of medical history and clinical observation. The Beighton criteria are widely used to assess the degree of joint hypermobility. DNA and biochemical studies can help identify affected individuals. Diagnostic tests include collagen gene mutation testing, collagen typing via skin biopsy, echocardiogram, and lysyl hydroxylase or oxidase activity. However, these tests are not able to confirm all cases, especially in instances of an unmapped mutation, so clinical evaluation by a geneticist remains essential. If there are multiple affected individuals in a family, it may be possible to perform prenatal diagnosis using a DNA information technique known as a linkage study. There is poor knowledge about EDS among practitioners.

CDGP is not associated with increased mortality because it is a variant of normal growth rather than a disease. However, in some affected individuals, it can be associated with significant psychological stress, resulting in poor self-image and social withdrawal. In recent years, researchers have also found that individuals with CDGP may be at increased risk for reduced bone mass in adulthood because of the delay in sex steroid influence on bone accrual during adolescence.