FHS shares some common features with Rubinstein–Taybi (due to overlapping effects of mutations on SRCAP), however cranial and hand anomalies are distinctive: broad thumbs, narrow palate, and microcephaly are absent in Floating-Harbor Syndrome. One child in the UK has a diagnosis of microcephaly alongside Floating–Harbor syndrome.

Until recently, doctors have diagnosed patients with FHS based on clinical observations and how well they fit the disease description, usually occurring in early childhood. Molecular genetic testing is also used now to test for genetic mutations. By performing a sequence analysis test of select exons, mutations can be detected in exon 34 of the SRCAP gene. This mutation has been observed in 19 patients to date.

In most cases, if the patient shows classic facial features of FHS, the molecular testing will show a mutation on the SRCAP gene.

The assessment for Smith-Finemen-Myers syndrome like any other mental retardation includes a detailed family history and physical exam that tests the mentality of the patient. The patient also gets a brain and skeletal imaging though CT scans or x-rays. They also does a chromosome study and certain other genetic biochemical tests to help figure out any other causes for the mental retardation.

The diagnosis of SFMS is based on visible and measurable symptoms. Until 2000, SFMS was not known to be associated with any particular gene. As of 2001, scientists do not yet know if other genes are involved in this rare disease. Generic analysis of the ATRX gene may prove to be helpful in diagnosis of SFMS.

The diagnosis of Wilson–Turner syndrome is based upon a clinical evaluation, a detailed patient history, and identification of characteristic features. Molecular genetic testing for mutations in the HDAC8 gene is now available to confirm the diagnosis.

The Wilson–Turner syndrome is characterized by mild to moderate range of intellectual disability, obesity, tapered fingers, and mood swings. Males also suffer from gynecomastia and hypogonadism. In order to be diagnosed with Wilson-Turner Syndrome, male patients must suffer from intellectual disability, obesity, and gynecomastia. Females do not necessarily have to have noticeable phenotype but can be diagnosed with this disorder by studying her family history and identifying others with the disorder. It has been noted that children with Wilson-Turner Syndrome will display speech development delay and excessive drooling. Males can be confirmed by testing androgen levels. Female carriers will show silencing of the gene a complex X inactivation.

A 2007 study followed 112 individuals for a mean of 12 years (mean age 25.3, range 12–71). No patient died during follow-up, but several required medical interventions. The mean final heights were 167 and 153 cm for men and women, respectively, which is approximately 2 standard deviations below normal.

Genetic testing may be available for mutations in the FGDY1 gene. Genetic counseling is indicated for individuals or families who may carry this condition, as there are overlapping features with fetal alcohol syndrome.

Other examinations or tests can help with diagnosis. These can include:

detailed family history

- conducting a detailed physical examination to document morphological features

- testing for genetic defect in FGDY1

- x-rays can identify skeletal abnormalities

- echo cardiogram can screen for heart abnormalities

- CT scan of the brain for cystic development

- X-ray of the teeth

- Ultrasound of abdomen to identify undescended testis

Diagnosis is based on clinical findings and can be confirmed by cytogenetic testing, when the deletion is in an average of 5 Mb (millions of base pairs). Nowadays is a common practice to run an aCHG (array chromosome hybridization genome) study on peripheral blood of the patient, in order to limit the extent of the loss of the genomic area, and the deleted genes.

First trimester ultrasound of noonan syndrome reveals nuchal oedema / cystic hygroma almost same as seen in Turner syndrome. Follow up scans may shows clinical features that already described above.

A study shows this disease is also associated with hepato splenomegaly with renal anomalies including malrotation and solitary kidney. A rare incidence of choledochal cyst is also reported as well.

Prevention for Alström Syndrome is considered to be harder compared to other diseases/syndromes because it is an inherited condition. However, there are other options that are available for parents with a family history of Alström Syndrome. Genetic testing and counseling are available where individuals are able to meet with a genetic counselor to discuss risks of having the children with the disease. The genetic counselor may also help determine whether individuals carry the defective ALSM1 gene before the individuals conceive a child. Some of the tests the genetic counselors perform include chorionic villus sampling (CVS), Preimplantation genetic diagnosis (PGD), and amniocentesis. With PGD, the embryos are tested for the ALSM1 gene and only the embryos that are not affected may be chosen for implantation via in vitro fertilization.

It is possible to clinically detect Alström syndrome in infancy, but more frequently, it is detected much later, as doctors tend to detect symptoms as separate problems. Currently, Alström syndrome is often diagnosed clinically, since genetic testing is costly and only available on a limited basis.

A physical examination would be needed to properly diagnose the patient. Certain physical characteristics can determine if the patient has some type of genetic disorder. Usually, a geneticist would perform the physical examination by measuring the distance around the head, distance between the eyes, and the length of arms and legs. In addition, examinations for the nervous system or the eyes may be performed. Various imaging studies like computerized tomography scans (CT), Magnetic Resonance Imaging (MRI), or X-rays are used to see the structures within the body.

Family and personal medical history are required. Information about the health of an individual is crucial because it provides traces to a genetic diagnosis.

Laboratory tests, particularly genetic testing, are performed to diagnose genetic disorders. Some of the types of genetic testing are molecular, biochemical, and chromosomal. Other laboratory tests performed may measure levels of certain substances in urine and blood that can also help suggest a diagnosis.

Diagnosis is made when several characteristic clinical signs are observed. There is no single test to confirm the presence of Weill–Marchesani syndrome. Exploring family history or examining other family members may prove helpful in confirming this diagnosis.

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.

While no genetic syndrome is capable of being cured, treatments are available for some symptoms. External fixators have been used for limbic and facial reconstructions.

Diagnosis is based on appearance and family history. KID syndrome or keratosis follicularis spinulosa decalvans have some similar symptoms and must be eliminated.

In 1989, diagnostic criteria was created for the diagnosing of Winchester syndrome. The typical diagnosis criteria begin with skeletal radiological test results and two of the defining symptoms, such as short stature, coarse facial features, hyperpigmentation, or excessive hair growth. The typical tests that are performed are x-ray and magnetic resonance imaging. It appears that Winchester syndrome is more common in women than men. Winchester syndrome is very rare. There have only been a few individuals worldwide who were reported to have this disorder.

Treatments are usually based on the individuals symptoms that are displayed. The seizures are controlled with anticonvulsant medication. For the behavior problems, the doctors proscribe to a few medications and behavioral modification routines that involve therapists and other types of therapy. Even if mental retardation is severe, it does not seem to shorten the lifespan of the patient or to get worse with age.

X-ray applications on most cases have brought about little outcome in most of the published case reports. As a consequence, a certain number of authors consider acrogeria mainly as a cutaneous affection, but the bone alterations are well described as part of the syndrome.

For patients who show typical alterations of acrogeria and metageria, in a concomitant way, the single term of "Acrometageria" has been proposed, which can refer to the widest spectrum of premature ageing syndromes.

However, this concept is still not generally accepted in the medical literature.As these are extremely rare syndromes, all sharing an aspect of aging skin similar to progeria, they are also called progeroid syndromes, from time to time.

It is traditionally characterized by hypotonia, short stature, hyperphagia, obesity, behavioral issues (specifically OCD-like behaviors), small hands and feet, hypogonadism, and mild intellectual disability. However, with early diagnosis and early treatment (such as with growth hormone therapy), the prognosis for persons with PWS is beginning to change. Like autism, PWS is a spectrum disorder and symptoms can range from mild to severe and may change throughout the person's lifetime. Various organ systems are affected.

Traditionally, Prader–Willi syndrome was diagnosed by clinical presentation. Currently, the syndrome is diagnosed through genetic testing; testing is recommended for newborns with pronounced hypotonia. Early diagnosis of PWS allows for early intervention as well as the early prescription of growth hormone. Daily recombinant growth hormone (GH) injections are indicated for children with PWS. GH supports linear growth and increased muscle mass, and may lessen food preoccupation and weight gain.

The mainstay of diagnosis is genetic testing, specifically DNA-based methylation testing to detect the absence of the paternally contributed Prader–Willi syndrome/Angelman syndrome (PWS/AS) region on chromosome 15q11-q13. Such testing detects over 97% of cases. Methylation-specific testing is important to confirm the diagnosis of PWS in all individuals, but especially those who are too young to manifest sufficient features to make the diagnosis on clinical grounds or in those individuals who have atypical findings.

Prader–Willi syndrome is often misdiagnosed as other syndromes due to many in the medical community's unfamiliarity with PWS. Sometimes it is misdiagnosed as Down syndrome, simply because of the relative frequency of Down syndrome compared to PWS.

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.

Cohen syndrome is diagnosed by clinical examination, but often difficult due to variation in expression.

Ocular complications, though rare, are listed as optic atrophy, microphthalmia, pigmentary chorioretinitis, hemeralopia (decreased vision in bright light), myopia, strabismus, nystagmus and iris/retinal coloboma.

General appearance is obesity with thin/elongated arms and legs. Micrognathia, short philtrum, and high vaulted palate are common. Variable mental retardation with occasional seizure and deafness also is characteristic of Cohen syndrome.

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.

The standard test for growth hormone deficiency is the growth hormone stimulation test. Peak levels of growth hormone below normal are considered confirmation of a growth hormone deficiency. Growth-impaired children with a normal stimulation test were considered suspect for having the Kowarski syndrome that may benefit from treatment with growth hormone.

Zadik et al. reported in 1990 that the growth hormone stimulation test is not reliable, suggesting the use of the more reliable 24-hour integrated concentration of growth hormone (IC-GH) as a better test. In 1995, they also suggested that some cases of the neurosecretory growth failure syndrome might have the Kowarski syndrome.

Albertsson-Wikland Kerstin confirmed in 1992 that the IC-GH test is a reproducible test for growth hormone deficiency and Carel et al. confirmed in 1997 that the reliability of the growth hormone stimulation tests was poor.

A 1987 study by Bistrizer et al suggested a diagnostic procedure that may be used to diagnose the Kowarski syndrome. Their study was based on the requirement for the growth hormone molecule to bind a specific binding molecule on the wall of the responsive cells to elicit its activity. Their study demonstrated a decrease ability of the growth hormone from children with the Kowarski syndrome to bind with living IM-9 cells. The test involved measuring the ratio between the levels of growth hormone by a radioreceptor assay (RRA-GH) to the level of growth hormone determined by the established radioimmunoassay (RIA-GH). The study found that the RRA-GH/RIA-GH ratio in NS subjects was normal but significantly below normal (P<0.005) in the Kowarski syndrome patients. The authors proposed the use of their test for the diagnosis of the Kowarski syndrome.

Bistrizer, Chalew and Kowarski demonstrated in 1995 that a modified RRA-GH/RIA-GH ratio test was a predictor for the responsiveness of growth-impaired children to growth hormone therapy.

The RRA-GH/RIA-GH ratio assay proposed by Bistrizer et al. can be used for screening of patients who may have the Kowarski syndrome thus more likely to respond to Growth Hormone therapy. Advances in the methodology for identifying spot mutations in the DNA of individuals demonstrated that the "Kowarski Syndrome is caused by various mutations in the GH1 gene (17q22-q24) that result in structural GH anomalies and a biologically inactive molecule." Testing individual patient for such mutation is offered on the Internet.

Eye surgery has been documented to help those with ocular diseases, such as some forms of glaucoma.

However, long term medical management of glaucoma has not proven to be successful for patients with Weill–Marchesani syndrome. Physical therapy and orthopedic treatments are generally prescribed for problems stemming from mobility from this connective tissue disorder. However, this disorder has no cure, and generally, treatments are given to improve quality of life.

Initially, the clinical presentation of SDS may appear similar to cystic fibrosis. However, CF can be excluded with a normal chloride in sweat test but faecal elastase as a marker of pancreatic function will be reduced. The variation, intermittent nature, and potential for long-term improvement of some clinical features make this syndrome difficult to diagnose. SDS may present with either malabsorption, or hematological problems. Rarely, SDS may present with skeletal defects, including severe rib cage abnormalities that lead to difficulty in breathing. Diagnosis is generally based on evidence of exocrine pancreatic dysfunction and neutropenia. Skeletal abnormalities and short stature are characteristics that can be used to support the diagnosis. The gene responsible for the disease has been identified and genetic testing is now available. Though useful in diagnostics, a genetic test does not surmount the need for careful clinical assessment and monitoring of all patients.