Genetic screening is also typically done postnatally, including PCR typing of microsatellite DNA and STS markers as well as comparative genomic hybridization (CGH) studies using DNA microarrays.

In some cases PCR and sequencing of the entire "SOX9" gene is used to diagnose CMD.

Many different translocation breakpoints and related chromosomal aberrations in patients with CMD have been identified.

Diagnosis of Crouzon syndrome usually can occur at birth by assessing the signs and symptoms of the baby. Further analysis, including radiographs, magnetic resonance imaging (MRI) scans, genetic testing, X-rays and CT scans can be used to confirm the diagnosis of Crouzon syndrome.

"In utero" sonographic diagnosis is possible when characteristic features such as bilateral bowed femurs and tibia, clubbed feet, prominent curvature of the neck, a bell-shaped chest, pelvic dilation, and/or an undersized jaw are apparent

Radiographic techniques are generally used only postnatally and also rely on prototypical physical characteristics.

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.

Recent research has been focused on studying large series of cases of 3-M syndrome to allow scientists to obtain more information behind the genes involved in the development of this disorder. Knowing more about the underlying mechanism can reveal new possibilities for treatment and prevention of genetic disorders like 3-M syndrome.

- One study looks at 33 cases of 3M syndrome, 23 of these cases were identified as CUL7 mutations: 12 being homozygotes and 11 being heterozygotes. This new research shows genetic heterogeneity in 3M syndrome, in contrast to the clinical homogeneity. Additional studies are still ongoing and will lead to the understanding of this new information.

- This study provides more insight on the three genes involved in 3M syndrome and how they interact with each other in normal development. It lead to the discovery that the CUL7, OBS1, and CCDC8 form a complex that functions to maintain microtubule and genomic integrity.

Treatment of 3-M syndrome is aimed at the specific symptoms presented in each individual. With the various symptoms of this disorder being properly managed and affected individuals having normal mental development, 3-M syndrome is not a life - threatening condition and individuals are able to lead a near normal life with normal life expectancy.

Treatment may involve the coordinated efforts of many healthcare professionals, such as pediatricians, orthopedists, dentists and/or other specialists depending on the symptoms.

- Possible management options for short stature are surgical bone lengthening or growth hormone therapy.

- Orthopedic techniques and surgery may be used to treat certain skeletal abnormalities.

- Plastic surgery may also be performed on individuals to help correct certain cranio-facial anomalies.

- Individuals with dental abnormalities may undergo corrective procedures such as braces or oral surgeries.

The presence of the disease can be confirmed with a genetic test. In a study of 10 infants with clinical indications of NSML prior to their first birthday, 8 (80%) patients were confirmed to have the suspected mutation. An additional patient with the suspected mutation was subsequently found to have NF1, following evaluation of the mother.

There are 5 identified allelic variants responsible for NSML. Y279C, T468M, A461T, G464A, and Q510P which seems to be a unique familial mutation, in that all other variants are caused by transition errors, rather than transversion.

Diagnosis is based on the distinctive cry and accompanying physical problems. These common symptoms are quite easily observed in infants. Affected children are typically diagnosed by a doctor or nurse at birth. Genetic counseling and genetic testing may be offered to families with individuals who have cri du chat syndrome. Prenatally the deletion of the cri du chat related region in the p arm of chromosome 5 can be detected from amniotic fluid or chorionic villi samples with BACs-on-Beads technology. G-banded karyotype of a carrier is also useful. Children may be treated by speech, physical and occupational therapists. Heart abnormalities often require surgical correction.

It is suggested that, once diagnosed, individuals be routinely followed by a cardiologist, endocrinologist, dermatologist, and other appropriate specialties as symptoms present.

It is recommended that those with the syndrome who are capable of having children seek genetic counseling before deciding to have children. As the syndrome presents frequently as a "forme fruste" (incomplete, or unusual form) variant, an examination of all family members must be undertaken. As an autosomal dominant trait there is a fifty percent chance with each child that they will also be born with the syndrome. Although fully penetrant, since the syndrome has variable expressivity, one generation may have a mild expression of the syndrome, while the next may be profoundly affected.

Once a decision to have children is made, and the couple conceives, the fetus is monitored during the pregnancy for cardiac evaluation. If a gross cardiac malformation is found, parents receive counseling on continuing with the pregnancy.

Other management is routine care as symptoms present:

1. For those with endocrine issues (low levels of thyrotopin [a pituitary hormone responsible for regulating thyroid hormones], follicle stimulating hormone) drug therapy is recommended.

2. For those who are disturbed by the appearance of lentigines, cryosurgery may be beneficial. Due to the large number of lentigines this may prove time consuming. An alternative treatment with tretinoin or hydroquinone creams may help.

3. Drug therapies for those with cardiac abnormalities, as those abnormalities become severe enough to warrant the use of these therapies. ECG's are mandatory prior to any surgical interventions, due to possible arrythmia.

Each child is different and it entirely depends on which sutures are fused and how it is affecting the child as to how it is treated. Some children have severe breathing issues due to shallow mid face and may require a tracheostomy. All should be treated at a specialist centre. Cranio bands are not used in the UK.

Surgery is typically used to prevent the closure of sutures of the skull from damaging the brain's development. Without surgery, blindness and mental retardation are typical outcomes. Craniofacial surgery is a discipline of both plastic surgery and oral and maxillofacial surgery (OMFS) . To move the orbits forward, craniofacial surgeons expose the skull and orbits and reshape the bone. To treat the midface deficiency, craniofacial surgeons can move the lower orbit and midface bones forward. For jaw surgery, either plastic surgeons or OMFS surgeons can perform these operations.

Crouzon patients tend to have multiple sutures involved, most specifically bilateral coronal craniosynostoses, and either open vault surgery or strip craniectomy (if child is under 6 months) can be performed. In the later scenario, a helmet is worn for several months following surgery.

Once treated for the cranial vault symptoms, Crouzon patients generally go on to live a normal lifespan.

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.

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.

Many features of gerodermia osteodysplastica (GO) and another autosomal recessive form of cutis laxa, wrinkly skin syndrome (WSS, ""), are similar to such an extent that both disorders were believed to be variable phenotypes of a single disorder.

Several delineating factors, however, suggest that gerodermia osteodysplastica and wrinkly skin syndrome are distinct entities, but share the same clinic spectrum.

While the prevailing feature of wrinkly, loose skin is more localized with GO, it is usually systemic, yet eases in severity with age during the course of WSS. Also, as the fontanelles ("soft spots") are usually normal on the heads of infants with GO, they are often enlarged in WSS infants.

While WSS is associated with mutations of genes on chromosomes 2, 5, 7, 11 and 14; GO has been linked to mutations in the protein GORAB. A serum sialotransferrin type 2 pattern, also observed with WSS, is not present in GO patients.

But perhaps the most notable feature, differentiating GO from WSS and similar cutis laxa disorders, is the age-specific metaphyseal peg sometimes found in GO-affected long bone, near the knee. Not appearing until around age 4–5, then disappearing by physeal closure, this oddity of bone is thought to represent a specific genetic marker unique to GO and its effects on bone development.

There is a deficiency of malate in patients because fumarase enzyme can't convert fumarate into it therefore treatment is with oral malic acid which will allow the krebs cycle to continue, and eventually make ATP.

Treatment of cause: Due to the genetic cause, no treatment of the cause is possible.

Treatment of manifestations: routine treatment of ophthalmologic, cardiac, and neurologic findings; speech, occupational, and physical therapies as appropriate; specialized learning programs to meet individual needs; antiepileptic drugs or antipsychotic medications as needed.

Surveillance: routine pediatric care; routine developmental assessments; monitoring of specific identified medical issues.

Nicolaides–Baraitser syndrome (NCBRS) is a rare genetic condition caused by de novo missense mutations in the SMARCA2 gene and has only been reported in less than 100 cases worldwide. NCBRS is a distinct condition and well recognizable once the symptoms have been identified.

The most common symptoms of Nicolaides–Baraitser syndrome are mild to severe developmental delays with absent or limited speech, seizures, short stature, sparse hair, typical facial characteristics, brachydactyly, and prominent finger joints and broad distal phalanges.

Respiratory complications are often cause of death in early infancy.

Marshall–Smith syndrome is not to be confused with:

- Marshall syndrome (aka.Periodic fever, aphthous stomatitis, pharyngitis and adenitis (PFAPA syndrome, see also: Periodic fever syndrome)

- Sotos (like) syndrome

- Weaver-Smith syndrome (WSS)

Pancreatic exocrine insufficiency may be treated through pancreatic enzyme supplementation, while severe skeletal abnormalities may require surgical intervention. Neutropenia may be treated with granulocyte-colony stimulating factor (GCSF) to boost peripheral neutrophil counts. However, there is ongoing and unresolved concern that this drug could contribute to the development of leukemia. Signs of progressive marrow failure may warrant bone marrow transplantation (BMT). This has been used successfully to treat hematological aspects of disease. However, SDS patients have an elevated occurrence of BMT-related adverse events, including graft-versus-host disease (GVHD) and toxicity relating to the pre-transplant conditioning regimen. In the long run, study of the gene that is mutated in SDS should improve understanding of the molecular basis of disease. This, in turn, may lead to novel therapeutic strategies, including gene therapy and other gene- or protein-based approaches.

A 'de novo'-situation appears in about 75% of the cases. In 25% of the cases, one of the parents is carrier of the syndrome, without any effect on the parent. Sometimes adults have mild problems with the syndrome. To find out whether either of the parents carries the syndrome, both parents have to be tested. In several cases, the syndrome was identified with the child, because of an autism disorder or another problem, and later it appeared that the parent was affected as well. In families where both parents have tested negative for the syndrome, chances of a second child with the syndrome are extremely low. If the syndrome was found in the family, chances of a second child with the syndrome are 50%, because the syndrome is autosomal dominant. The effect of the syndrome on the child cannot be predicted.

As of October 2012, Unique, an international rare chromosome disorder group and registry, has 64 genetically-confirmed cases of this deletion worldwide.

The Syndrome can be detected with fluorescence in situ hybridization.

For parents with a child with the syndrome, it is advisable to consult a physician before another pregnancy.

Gerodermia osteodysplastica (GO), also called geroderma osteodysplasticum and Walt Disney dwarfism, is a rare autosomal recessive connective tissue disorder included in the spectrum of cutis laxa syndromes.

Usage of the name "Walt Disney dwarfism" is attributed to the first known case of the disorder, documented in a 1950 journal report, in which the authors described five affected members from a Swiss family as having the physical appearance of dwarves from a Walt Disney film.

The terms "geroderma" or "gerodermia" can be used interchangeably with "osteodysplastica" or "osteodysplasticum", with the term "hereditaria" sometimes appearing at the end.

Typically a coloboma appears oval or comet shaped with round end towards the centre. There may be a few vessels (retinal or choroidal) at the edges. The surface may have irregular depression.

The diagnosis of lissencephaly is usually made at birth or soon after by ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI). However, these results should be interpreted cautiously since even experienced radiologists can misdiagnose polymicrogyria, a different developmental malformation of the brain, as lissencephaly.

Before birth, complex ultrasounds performed routinely during pregnancy may indicate the presence of cerebral abnormality, but this method of diagnosis should be complemented by other methods, such as genetic studies and NMR, and the examination is not recommended as part of routine ultrasound examinations, unless family medical history or other reasons for suspecting brain malformation are present. The earliest point during gestation when it is possible to observe abnormal development of the brain surface is approximately in week 20, although ultrasound examinations in week 25–30 are more common. Up to this time, the fetal brain normally has a smooth appearance. If lissencephaly is suspected, chorionic villus sampling can test for some lissencephaly variants, but only those with a known genetic mutation.

Signs of Rett syndrome that are similar to autism:

Signs of Rett syndrome that are also present in cerebral palsy (regression of the type seen in Rett syndrome would be unusual in cerebral palsy; this confusion could rarely be made):