MdDS is diagnosed several ways, one being by the symptoms: in particular, the "constant rocking, swaying feeling" and the abatement of this feeling when in motion again and as a matter of exclusion. There are no definitive tests that confirm MdDS, only tests that rule out other conditions. Tests include hearing and balance, and MdDS is generally diagnosed by either a neurologist or an ear nose & throat specialist.

At least one clinical trial on readaptation of the vestibulo-ocular reflex undertaken by Dr Mingjia Dai from Mount Sinai Hospital in New York City has produced results for a significant percentage of patients who have participated in the program.

Dai has developed an intervention that provided improvement in symptoms for 70% of the patients in the clinical trial phase. The protocol involves a physical manipulation of the patient intended to readapt the vestibulo-ocular reflex. While the program is no longer in the research phase, Dai continues to accept patients. According to Dai, "success" is measured as a 50% reduction of symptoms.

Recent research reveals a very small percentage of MdDS cases may be related to optokinetic nystagmus (OKN).

Diagnosis of Harlequin syndrome is made when the individual has consistent signs and symptoms of the condition, therefore, it is made by clinical observation. In addition, a neurologist or primary care physician may require an MRI test to rule out similar disorders such as Horner's syndrome, Adie's syndrome, and Ross' syndrome. In an MRI, a radiologist may observe areas near brain or spinal cord for lesions, or any damage to the nerve endings. It is also important that the clinician rules out traumatic causes by performing autonomic function tests. Such tests includes the following: tilt table test, orthostatic blood pressure measurement, head-up test, valsalva maneuver, thermoregulatory sweat test, tendon reflex test, and electrocardiography (ECG). CT scan of the heart and lungs may also be performed to rule out a structural underlying lesion. The medical history of the individual should be carefully noted.

One possible cause of Harlequin syndrome is a lesion to the preganglionic or postganglionic cervical sympathetic fibers and parasympathetic neurons of the ciliary ganglion. It is also believed that torsion (twisting) of the thoracic spine can cause blockage of the anterior radicular artery leading to Harlequin syndrome. The sympathetic deficit on the denervated side causes the flushing of the opposite side to appear more pronounced. It is unclear whether or not the response of the undamaged side was normal or excessive, but it is believed that it could be a result of the body attempting to compensate for the damaged side and maintain homeostasis.

Since the cause and mechanism of Harlequin syndrome is still unknown, there is no way to prevent this syndrome.

Diagnosis can be made by EEG. In case of epileptic spasms, EEG shows typical patterns.

Occasionally the syndrome is referred to as "idiopathic" West syndrome, when a cause cannot be determined. Important diagnostic criteria are:

- Regular development until the onset of the attacks or before the beginning of the therapy

- no pathological findings in neurological or neuroradiological studies

- no evidence of a trigger for the spasms

Those are becoming rare due to modern medicine.

Carrier testing for Roberts syndrome requires prior identification of the disease-causing mutation in the family. Carriers for the disorder are heterozygotes due to the autosomal recessive nature of the disease. Carriers are also not at risk for contracting Roberts syndrome themselves. A prenatal diagnosis of Roberts syndrome requires an ultrasound examination paired with cytogenetic testing or prior identification of the disease-causing ESCO2 mutations in the family.

Cytogenetic preparations that have been stained by either Giemsa or C-banding techniques will show two characteristic chromosomal abnormalities. The first chromosomal abnormality is called premature centromere separation (PCS) and is the most likely pathogenic mechanism for Roberts syndrome. Chromosomes that have PCS will have their centromeres separate during metaphase rather than anaphase (one phase earlier than normal chromosomes). The second chromosomal abnormality is called heterochromatin repulsion (HR). Chromosomes that have HR experience separation of the heterochromatic regions during metaphase. Chromosomes with these two abnormalities will display a "railroad track" appearance because of the absence of primary constriction and repulsion at the heterochromatic regions. The heterochromatic regions are the areas near the centromeres and nucleolar organizers. Carrier status cannot be determined by cytogenetic testing. Other common findings of cytogenetic testing on Roberts syndrome patients are listed below.

- Aneuploidy- the occurrence of one or more extra or missing chromosomes

- Micronucleation- nucleus is smaller than normal

- Multilobulated Nuclei- the nucleus has more than one lobe

Screening generally only takes place among those displaying several of the symptoms of ABCD, but a study on a large group of institutionalized deaf people in Columbia revealed that 5.38% of them were Waardenburg patients. Because of its rarity, none of the patients were diagnosed with ABCD (Waardenburg Type IV). Nothing can be done to prevent the disease.

In terms of the diagnosis of Romano–Ward syndrome the following is done to ascertain the condition(the "Schwartz Score" helps in so doing):

- Exercise test

- ECG

- Family history

Diagnosis depends on the clinical scenario. However, karyotyping is an essential test for diagnosis.

The occurrence of WS has been reported to be one in 45,000 in Europe. The diagnosis can be made prenatally by ultrasound due to the phenotype displaying pigmentary disturbances, facial abnormalities, and other developmental defects. After birth, the diagnosis is initially made symptomatically and can be confirmed through genetic testing. If the diagnosis is not made early enough, complications can arise from

Hirschsprung's disease.

Pleurothotonus, commonly known as Pisa syndrome, is a rare neurological disorder which occurs due to prolonged exposure to antipsychotic drugs (which may also be referred to as neuroleptics). It is characterized by dystonia, and abnormal and sustained involuntary muscle contraction. This may cause twisting or jerking movements of the body or a body part. Although Pisa syndrome develops most commonly in those undergoing long-term treatment with antipsychotics, it has been reported less frequently in patients receiving other medications, such as an acetylcholinesterase inhibitor. However, it has also been seen in those with other diseases causing neurodegeneration and in those who are not receiving any medication (idiopathic Pisa syndrome). The characteristic development of Pisa syndrome consists of two types of dystonia: acute dystonia and tardive dystonia (also known as tardive dyskinesia). The underlying pathology of drug-induced Pisa syndrome is very complex, and development may be due to an underlying dopaminergic-cholinergic imbalance, or serotonergic/noradrenergic dysfunction.

Diagnosis is made based on features as well as by the very early onset of serious eye and ear disease. Because Marshall syndrome is an autosomal dominant hereditary disease, physicians can also note the characteristic appearance of the biological parent of the child. There are no tests for Stickler syndrome or Marshall syndrome. Some families with Stickler syndrome have been shown to have mutations in the Type II collagen gene on chromosome 1. However, other families do not show the linkage to the collagen gene. It is an area of active research, also the genetic testing being expensive supports that the diagnosis is made depending on the features.

There are two lines of treatment for Pisa syndrome. The first line entails discontinuation or reduction in dose of the antipsychotic drug(s). The second line of treatment is an anticholinergic medication. A pharmacological therapy for Pisa syndrome caused by prolonged use of antipsychotic drugs has not been established yet.

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

In the United States, sarcoidosis has a prevalence of approximately 10 cases per 100,000 whites and 36 cases per 100,000 blacks. Heerfordt syndrome is present in 4.1–5.6% of those with sarcoidosis.

If a contracture is less than 30 degrees, it may not interfere with normal functioning. The common treatment is splinting and occupational therapy. Surgery is the last option for most cases as the result may not be satisfactory.

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)

In terms of diagnosis for this condition, the following methods/tests are available:

- Endoscopic

- CT scan

- Serum endocrine autoantibody screen

- Histologic test

There is no medical treatment for either syndrome but there are some recommendations that can help with prevention or early identification of some of the problems. Children with either syndrome should have their hearing tested, and adults should be aware that the hearing loss may not develop until the adult years. Yearly visits to an ophthalmologist or other eye care professional who has been informed of the diagnosis of Stickler or Marshall syndrome is important for all affected individuals. Children should have the opportunity to have myopia corrected as early as possible, and treatment for cataracts or detached retinas may be more effective with early identification. Support for the joints is especially important during sports, and some recommend that contact sports should be avoided by those who have very loose joints.

Diagnosis involves consideration of physical features and genetic testing. Presence of split uvula is a differentiating characteristic from Marfan Syndrome, as well as the severity of the heart defects. Loeys-Dietz Syndrome patients have more severe heart involvement and it is advised that they be treated for enlarged aorta earlier due to the increased risk of early rupture in Loeys-Dietz patients. Because different people express different combinations of symptoms and the syndrome was identified in 2005, many doctors may not be aware of its existence, although clinical guidelines were released in 2014-2015. Dr. Harold Dietz, Dr. Bart Loeys, and Dr. Kenneth Zahka are considered experts in this condition.

Diagnosis of oculocerebrorenal syndrome can be done via genetic testing Among the different investigations that can de done are:

- Urinalysis

- MRI

- Blood test

It is suggested that the diagnostic criteria for Malpuech syndrome should include cleft lip and/or palate, typical associated facial features, and at least two of the following: urogenital anomalies, caudal appendage, and growth or developmental delay.

Due to the relatively high rate of hearing impairment found with the disorder, it too may be considered in the diagnosis. Another congenital disorder, Wolf-Hirschhorn (Pitt-Rogers-Danks) syndrome, shares Malpuech features in its diagnostic criteria. Because of this lacking differentiation, karyotyping (microscopic analysis of the chromosomes of an individual) can be employed to distinguish the two. Whereas deletions in the short arm of chromosome 4 would be revealed with Wolf-Hirschhorn, a karyotype without this aberration present would favor a Malpuech syndrome diagnosis. Also, the karyotype of an individual with Malpuech syndrome alone will be normal.