A diagnosis of beta-mannosidosis is suspected based on the persons clinical presentation. Urine testing to identify abnormal oligosaccharides is a useful screening test, and enzymatic analysis or molecular testing can be used for confirmation.

Diagnostic techniques for this condition can be done to offer a DDx, via lectin histochemistry to distinguish between α-mannosidosis and beta-mannosidosis.

Patients who develop PSH after traumatic injury have longer hospitalization and longer durations in intensive care in cases where ICU treatment is necessary. Patients often are more vulnerable to infections and spend longer times on ventilators, which can lead to an increased risk of various lung diseases. PSH does not affect mortality rate, but it increases the amount of time it takes a patient to recover from injury, compared to patients with similar injuries who do not develop PSH episodes. It often takes patients who develop PSH longer to reach similar levels of the brain activity seen in patients who do not develop PSH, although PSH patients do eventually reach these same levels.

Diagnosing PSH can be very difficult due to the lack of common terminology in circulation and a lack of diagnostic criteria. Different systems for diagnosis have been proposed, but a universal system has not been embraced. One example of a proposed system of diagnosis requires observation confirmation for four of the six following symptoms: fever greater than 38.3 degrees Celsius, tachycardia classified as a heart rate of 120 bpm or higher, hypertension classified as a systolic pressure higher than 160 mmHg or a pulse pressure higher than 80 mmHg, tachypnea classified as respiration rate higher than 30 breaths per minute, excess sweating, and severe dystonia. Ruling out other diseases or syndromes that show similar symptoms is imperative to diagnosis as well. Sepsis, encephalitis, neuroleptic malignant syndrome,

malignant hyperthermia, lethal catatonia, spinal cord injury (not associated with PSH), seizures, and hydrocephalus (this can be associated with PSH) are examples of diagnoses that should be considered due to the manifestation of similar symptoms before confirming a diagnosis of PSH. PSH has no simple radiological features that can be observed or detected on a scan.

A prenatal diagnosis was made by Kleijer et al. in 1979 by measuring beta-galactosidase and neuraminidase activities in cultured amniotic fluid cells.

Onset of adult GM1 is between ages 3 and 30.

Symptoms include muscle atrophy, neurological complications that are less severe and progress at a slower rate than in other forms of the disorder, corneal clouding in some patients, and dystonia (sustained muscle contractions that cause twisting and repetitive movements or abnormal postures). Angiokeratomas may develop on the lower part of the trunk of the body. Most patients have a normal size liver and spleen.

Prenatal diagnosis is possible by measurement of Acid Beta Galactosidase in cultured amniotic cells.

Genetic testing methods such as fluorescence in situ hybridization (FISH) and chromosomal microarray are available for diagnosing Dup15q syndrome and similar genetic disorders.

With the increase in genetic testing availability, more often duplications outside of the 15q11.2-13.1 region are being diagnosed. The global chromosome 15q11.2-13.1 duplication syndrome specific groups only provide medical information and research for chromosome 15q11.2-13.1 duplication syndrome and not the outlying 15q duplications.

It is associated with cathepsin A.This disease is due to mutations in the CTSA gene which encodes the protective protein/cathepsin A (PPCA). This in turn leads to a secondary deficiency of beta-galactosidase (GLB1) and neuraminidase 1 (NEU1).There are three distinct CTSA isoforms.

The most commonly effective treatment is clonazepam, which leads to the increased efficacy of another inhibitory neurotransmitter, GABA. There are anecdotal reports of the use of Levetiracetam in genetic and acquired hyperekplexia. During attacks of hypertonia and apnea, the limbs and head may be flexed towards the trunk in order to dissipate the symptoms. This is named the Vigevano maneuver after the doctor who invented it.

The GM1 gangliosidoses (or GM1 gangliosidos"i"s) are caused by a deficiency of beta-galactosidase, with resulting abnormal storage of acidic lipid materials in cells of the central and peripheral nervous systems, but particularly in the nerve cells.

GM1 Gangliosidoses are inherited, autosomal recessive sphingolipidoses, resulting from marked deficiency of Acid Beta Galactosidase.

Recent studies have explored the connection between DβH deficiency, Droxidopa treatment, and the effect on orthostatic tolerance and glucose homeostasis. It was found that Droxidopa increased acute and late glucose-stimulated insulin secretion and improved patients' insulin sensitivity. However, the use of Droxidopa was found to only produce "modest changes in glucose homeostasis" overall. This shows that treatment modalities other than Droxidopa should be pursued as possible adjuncts for the hyperinsulinemia seen in DβH deficiency.

Patients with Dup15q syndrome feature a distinctive electroencephalography (EEG) signature or biomarker in the form of high amplitude spontaneous beta frequency (12–30 Hz) oscillations. This EEG signature was first noted as a qualitative pattern in clinical EEG readings and was later described quantitatively by researchers at the UCLA and their collaborators within the network of national Dup15q clinics. This group of researchers found that beta activity in children with Dup15q syndrome is significantly greater than that observed in (1) healthy, typically developing children of the same age and (2) children of the same age and IQ with autism not caused by a known genetic disorder (i.e., nonsyndromic ASD). The EEG signature appears almost identical to beta oscillations induced by benzodiazepine drugs that modulate GABA receptors, suggesting that the signature is driven by overexpression of duplicated GABA receptor genes "GABRA5", "GABRB3", and "GABRG3". Treatment monitoring and identification of molecular disease mechanisms may be facilitated by this biomarker.

This is a form of dysautonomia but differentiated from familial dysautonomia by a lack of familial dysautonomic symptoms such as loss of sense of pain and smell. While L-threo-DOPS has been described as being "very effective for restoring noradrenergic tone and correcting postural hypotension, response to treatment is variable and the long-term and functional outcome is unknown."

Researchers have put together retrospective data collections in order to better under the progression of this orphan disease. Most studies show a perinatal period marked by inadequacy of the ANS to control blood pressure, blood sugar, and body temperature. The experiences of orthostatic hypotension, exercise intolerance, and "traumatic morbidity related to falls and syncope" have been documented later in lives of people with this condition. To provide a basis for improving the understanding of the epidemiology, genotype/phenotype correlation, outcome of these diseases, their impact on the quality of life of patients, and for evaluating diagnostic and therapeutic strategies, a patient registry was established by the non-commercial International Working Group on Neurotransmitter Related Disorders (iNTD).

Hyperekplexia ("exaggerated surprise") is a neurologic disorder classically characterised by pronounced startle responses to tactile or acoustic stimuli and hypertonia. The hypertonia may be predominantly truncal, attenuated during sleep and less prominent after a year of age. Classic hyperekplexia is caused by genetic mutations in a number of different genes, all of which play an important role in glycine neurotransmission. Glycine is used by the central nervous system as an inhibitory neurotransmitter. Hyperekplexia is generally classified as a genetic disease, but some disorders can mimic the exaggerated startle of hyperekplexia.

Dahlberg Borer Newcomer syndrome is a rare autosomal X-linked recessive genetic condition characterized by a prolapse of the bicuspid valve, progressive kidney failure, congenital lymphedema, hypoparathyroidism, and very short end bones of fingers. Treatment for this condition is based on its symptoms. These treatments may include manual lymphatic drainage, consumption of beta blockers or anticoagulants for the bicuspid valve prolapse and vitamin D or calcium carbonate tablets for the hypoparathyroidism.

This condition is also known as Lymphedema hypoparathyroidism syndrome, Hypoparathyroidism lymphedema syndrome, and simply Dahlberg syndrome.

GM2-gangliosidosis, AB variant is a rare, autosomal recessive metabolic disorder that causes progressive destruction of nerve cells in the brain and spinal cord. It has a similar pathology to Sandhoff disease and Tay-Sachs disease. The three diseases are classified together as the GM2 gangliosidoses, because each disease represents a distinct molecular point of failure in the activation of the same enzyme, beta-hexosaminidase. AB variant is caused by a failure in the gene that makes an enzyme cofactor for beta-hexosaminidase, called the GM2 activator.

Genetic testing is available for symptomatic individuals and asymptomatic relatives.

Diabetes mellitus is characterized by recurrent or persistent hyperglycemia, and is diagnosed by demonstrating any one of the following:

- Fasting plasma glucose level at or above 7.0 mmol/L (126 mg/dL).

- Plasma glucose at or above 11.1 mmol/L (200 mg/dL) two hours after a 75 g oral glucose load as in a glucose tolerance test.

- Symptoms of hyperglycemia and casual plasma glucose at or above 11.1 mmol/L (200 mg/dL).

- Glycated hemoglobin (hemoglobin A1C) at or above 48 mmol/mol (≥ 6.5 DCCT %). (This criterion was recommended by the American Diabetes Association in 2010, although it has yet to be adopted by the WHO.)

About a quarter of people with new type 1 diabetes have developed some degree of diabetic ketoacidosis (a type of metabolic acidosis which is caused by high concentrations of ketone bodies, formed by the breakdown of fatty acids and the deamination of amino acids) by the time the diabetes is recognized. The diagnosis of other types of diabetes is usually made in other ways. These include ordinary health screening, detection of hyperglycemia during other medical investigations, and secondary symptoms such as vision changes or unexplained fatigue. Diabetes is often detected when a person suffers a problem that may be caused by diabetes, such as a heart attack, stroke, neuropathy, poor wound healing or a foot ulcer, certain eye problems, certain fungal infections, or delivering a baby with macrosomia or hypoglycemia (low blood sugar).

A positive result, in the absence of unequivocal hyperglycemia, should be confirmed by a repeat of any of the above-listed methods on a different day. Most physicians prefer to measure a fasting glucose level because of the ease of measurement and the considerable time commitment of formal glucose tolerance testing, which takes two hours to complete and offers no prognostic advantage over the fasting test. According to the current definition, two fasting glucose measurements above 126 mg/dL (7.0 mmol/L) is considered diagnostic for diabetes mellitus.

In type 1, pancreatic beta cells in the islets of Langerhans are destroyed, decreasing endogenous insulin production. This distinguishes type 1's origin from type 2. Type 2 diabetes is characterized by insulin resistance, while type 1 diabetes is characterized by insulin deficiency, generally without insulin resistance. Another hallmark of type 1 diabetes is islet autoreactivity, which is generally measured by the presence of autoantibodies directed towards the beta cells.

The appearance of diabetes-related autoantibodies has been shown to be able to predict the appearance of diabetes type 1 before any hyperglycemia arises, the main ones being islet cell autoantibodies, insulin autoantibodies, autoantibodies targeting the 65-kDa isoform of glutamic acid decarboxylase (GAD), autoantibodies targeting the phosphatase-related IA-2 molecule, and zinc transporter autoantibodies (ZnT8). By definition, the diagnosis of diabetes type 1 can be made first at the appearance of clinical symptoms and/or signs, but the emergence of autoantibodies may itself be termed "latent autoimmune diabetes". Not everyone with autoantibodies progresses to diabetes type 1, but the risk increases with the number of antibody types, with three to four antibody types giving a risk of progressing to diabetes type 1 of 60%–100%. The time interval from emergence of autoantibodies to clinically diagnosable diabetes can be a few months in infants and young children, but in some people it may take years – in some cases more than 10 years. Islet cell autoantibodies are detected by conventional immunofluorescence, while the rest are measured with specific radiobinding assays.

There are no known ways of preventing LADA type 1 diabetes, though some researchers believe it could be stopped at a very early stage if a diagnosis is made prior to the body's destruction of its beta cells.

Brittle asthma is a type of asthma distinguishable from other forms by recurrent, severe attacks.

There are two subtypes divided by symptoms: Type 1 and Type 2, depending on the stability of the patient's maximum speed of expiration, or peak expiratory flow rate (PEFR). Type 1 is characterized by sustained, chronic variability of PEFR, while type 2 is distinguished by sudden unpredictable drops in PEFR where asthma symptoms are otherwise well controlled and the function of the lungs is not substantially impaired.

Brittle asthma is one of the "unstable" subtypes of "difficult asthma", a term used to characterize the less than 5% of asthma cases that do not respond to maximal inhaled treatment, including high doses of corticosteroids combined with additional therapies such as long-acting beta-2 agonists.

Psychedelics such as LSD-25 and psilocybin-containing mushrooms demonstrate very rapid tachyphylaxis. In other words, one may be unable to 'trip' two days in a row. Some people are able to 'trip' by taking up to three times the dosage, yet some users may not be able to negate tachyphylaxis at all until a period of days has gone by.

Mutations in the GM2A gene cause GM2-gangliosidosis, AB variant. This condition is inherited in an autosomal recessive pattern.

The GM2A gene provides instructions for making a protein called the GM2 activator. This protein is required for the normal function of beta-hexosaminidase A, a critical enzyme in the nervous system that breaks down a lipid called GM2 ganglioside. If mutations in both alleles at this locus disrupt the activity of the GM2 activator, beta-hexosaminidase A cannot perform its normal function. As a result, gangliosides accumulate in the central nervous system until they interfere with normal biological processes. Progressive damage caused by buildup of gangliosides leads to the destruction of nerve cells.

GM2-gangliosidosis, AB variant is extremely rare. In contrast with both Tay-Sachs disease and Sandhoff disease, in which many mutant polymorphic alleles have been discovered, including pseudodeficiency alleles, very few GM2A mutations have been reported. When AB variant is reported, in often occurs with consanguineous parents or in genetically isolated populations.

GM2A is expressed in many tissues, and the GM2 activator protein has been reported to have other cellular functions. Because AB variant is so rarely diagnosed, it is likely that most mutations of GM2A are fatal at the embryionic or fetal stage of development in homozygotes and genetic compounds, and thus are never observed clinically.

Glutamic acid decarboxylase autoantibodies (GADA), islet cell autoantibodies (ICA), insulinoma-associated (IA-2) autoantibodies, and zinc transporter autoantibodies (ZnT8) are all associated with LADA; GADAs are commonly found in cases of diabetes mellitus type 1.

The presence of Islet Cell Complement Fixing Autoantibodies also aids in a differential diagnosis between LADA and type 2 diabetes. Persons with LADA often test positive for ICA, whereas type 2 diabetics only seldom do.

Persons with LADA usually test positive for Glutamic acid decarboxylase antibodies, whereas in type 1 diabetes these antibodies are more commonly seen in adults rather than in children. In addition to being useful in making an early diagnosis for type 1 diabetes mellitus, GAD antibodies tests are used for differential diagnosis between LADA and type 2 diabetes and may also be used for differential diagnosis of gestational diabetes, risk prediction in immediate family members for type 1, as well as a tool to monitor prognosis of the clinical progression of type 1 diabetes.

In a patient fully withdrawn from opioids, going back to an intermittent schedule or maintenance dosing protocol, a fraction of the old tolerance level will rapidly develop, usually starting two days after therapy is resumed and, in general, leveling off after day 7. Whether this is caused directly by opioid receptors modified in the past or affecting a change in some metabolic set-point is unclear. Increasing the dose will usually restore efficacy; relatively rapid opioid rotation may also be of use if the increase in tolerance continues.