The symptoms of Klinefelter syndrome are often variable; therefore, a karyotype analysis should be ordered when small testes, infertility, gynecomastia, long legs/arms, developmental delay, speech/language deficits, learning disabilities/academic issues and/or behavioral issues are present in an individual. The differential diagnosis for the Klinefelter syndrome can include the following conditions: fragile X syndrome, Kallmann syndrome and Marfan syndrome. The cause of hypogonadism can be attributed to many other different medical conditions.

There have been some reports of individuals with Klinefelter syndrome who also have other chromosome abnormalities, such as Down syndrome.

About 10% of Klinefelter cases are found by prenatal diagnosis. The first clinical features may appear in early childhood or, more frequently, during puberty, such as lack of secondary sexual characteristics and aspermatogenesis. Despite the presence of small testes, only a quarter of the affected males are recognized as having Klinefelter syndrome at puberty. Another quarter receive their diagnosis in late adulthood. About 64% of affected individuals are never recognized. Often the diagnosis is made incidentally as a result of examinations and medical visits for reasons not linked to the condition.

The standard diagnostic method is the analysis of the chromosomes' karyotype on lymphocytes. In the past, the observation of the Barr body was common practice as well. To confirm mosaicism, it is also possible to analyze the karyotype using dermal fibroblasts or testicular tissue.

Other methods may be: research of high serum levels of gonadotropins (follicle-stimulating hormone and luteinizing hormone), presence of azoospermia, determination of the sex chromatin, and prenatally via chorionic villus sampling or amniocentesis. A 2002 literature review of elective abortion rates found that approximately 58% of pregnancies in the United States with a diagnosis of Klinefelter syndrome were terminated.

In general, idic(15) occurs de novo but the parents must be karyotyped to make sure it is not inherited, mostly because this will affect the course of genetic counseling given to the family. If the abnormality is found prenatally and one of the parents harbour the marker, the child has a chance of not carrying the mutation. Further tests should however be done to prove the marker has not been rearranged while being inherited. This information is also necessary for counseling of future pregnancies. Each family is unique and should therefore be handled individually.

The extra chromosome in people with idic(15) can be easily detected through chromosome analysis (karyotyping). Additional tests are usually required. FISH (Fluorescent in situ hybridization) is used to confirm the diagnosis by distinguishing idic(15) from other supernumerary marker chromosomes. Array CGH can be used to determine the gene content and magnitude of copy number variation so that the clinical picture can be foreseen.

Interstitial duplications of chromosome 15 can be more difficult to detect on a routine chromosome analysis but are clearly identifiable using a 15q FISH study. Families should always discuss the results of chromosome and FISH studies with a genetic counselor or other genetics professionals to ensure accurate interpretation.

Edwards syndrome occurs in about one in 5,000 live births, but more conceptions are affected by the syndrome because the majority of those diagnosed with the condition prenatally will not survive to birth. Although women in their 20s and early 30s may conceive babies with Edwards syndrome, the risk of conceiving a child with it increases with a woman's age. The average maternal age for conceiving a child with this disorder is 32½.

Pre-implantation genetic diagnosis (PGD or PIGD) is a technique used to identify genetically normal embryos and is useful for couples who have a family history of genetic disorders. This is an option for people choosing to procreate through IVF. PGD is considered difficult due to it being both time consuming and having success rates only comparable to routine IVF.

Blastomere biopsy is a technique in which blastomeres are removed from the zona pellucida. It is commonly used to detect aneuploidy. Genetic analysis is conducted once the procedure is complete. Additional studies are needed to assess the risk associated with the procedure.

Patients are usually managed by a multidisciplinary team including surgeons, gynecologists, and dermatologists because of the complex nature of this disorder. Follow-up for the increased risk of breast cancer risk includes monthly breast self-examination, annual breast examination, and mammography at age 30 or five years earlier than the youngest age of breast cancer in the family. The magnitude of the risk of breast cancer justifies routine screening with breast MRI as per published guidelines.

In 2008/2009, 495 diagnoses of Edwards syndrome (trisomy 18) were made in England and Wales, 92% of which were made prenatally, resulting in 339 abortions, 49 stillbirths/miscarriages/fetal deaths, 72 unknown outcomes, and 35 live births. Because about 3% of cases with unknown outcomes are likely to result in a live birth, the total number of live births is estimated to be 37 (2008/09 data are provisional). Major causes of death include apnea and heart abnormalities. It is impossible to predict an exact prognosis during pregnancy or the neonatal period. Half of the infants with this condition do not survive beyond the first week of life. The median lifespan is five to 15 days. About 8-12% of infants survive longer than 1 year. One percent of children live to age 10, though a retrospective Canadian study of 254 children with trisomy 18 demonstrated ten year survival of 9.8%.

There is an association between taking aspirin for viral illnesses and the development of Reye syndrome, but no animal model of Reye syndrome has been developed in which aspirin causes the condition.

The serious symptoms of Reye syndrome appear to result from damage to cellular mitochondria, at least in the liver, and there are a number of ways that aspirin could cause or exacerbate mitochondrial damage. A potential increased risk of developing Reye syndrome is one of the main reasons that aspirin has not been recommended for use in children and teenagers, the age group for which the risk of lasting serious effects is highest.

No research has found a definitive cause of Reye syndrome, and association with aspirin has been shown through epidemiological studies. The diagnosis of "Reye Syndrome" greatly decreased in the 1980s, when genetic testing for inborn errors of metabolism was becoming available in developed countries. A retrospective study of 49 survivors of cases diagnosed as "Reye's Syndrome" showed that the majority of the surviving patients had various metabolic disorders, particularly a fatty-acid oxidation disorder medium-chain acyl-CoA dehydrogenase deficiency.

In some countries, oral mouthcare product Bonjela (not the form specifically designed for teething) has labeling cautioning against its use in children, given its salicylate content. There have been no cases of Reye syndrome following its use, and the measure is a precaution. Other medications containing salicylates are often similarly labeled as a precaution.

The Centers for Disease Control and Prevention (CDC), the U.S. Surgeon General, the American Academy of Pediatrics (AAP) and the Food and Drug Administration (FDA) recommend that aspirin and combination products containing aspirin not be given to children under 19 years of age during episodes of fever-causing illnesses. Hence, in the United States, it is advised that the opinion of a doctor or pharmacist should be obtained before anyone under 19 years of age is given any medication containing aspirin (also known on some medicine labels as acetylsalicylate, salicylate, acetylsalicylic acid, ASA, or salicylic acid).

Current advice in the United Kingdom by the Committee on Safety of Medicines is that aspirin should not be given to those under the age of 16 years, unless specifically indicated in Kawasaki disease or in the prevention of blood clot formation.

As its name indicates, a person with the syndrome has one Y chromosome and four X chromosomes on the 23rd pair, thus having 49 chromosomes rather than the normal 46. As with most categories of aneuploidy disorders, 49,XXXXY syndrome is often accompanied by intellectual disability. It can be considered a form of 47, XXY Klinefelter syndrome, or a variant of it.

It is genetic but not hereditary. This means that while the genes of the parents cause the syndrome, there is a small chance of more than one child having the syndrome. The probability of inheriting the disease is about 1%.

The individuals with this syndrome are males, but 49, XXXXX also exists with similar characteristics.

Documented cases of Reye syndrome in adults are rare. The recovery of adults with the syndrome is generally complete, with liver and brain function returning to normal within two weeks of onset. In children, however, mild to severe permanent brain damage is possible, especially in infants. Over thirty percent of the cases reported in the United States from 1981 through 1997 resulted in fatality.

At present, treatment for distal 18q- is symptomatic, meaning the focus is on treating the signs and symptoms of the conditions as they arise. To ensure early diagnosis and treatment, people with distal 18q- are suggested to undergo routine screenings for thyroid, hearing, and vision problems.

Suspicion of a chromosome abnormality is typically raised due to the presence of developmental delays or birth defects. Diagnosis of distal 18q- is usually made from a blood sample. A routine chromosome analysis, or karyotype, is usually used to make the initial diagnosis, although it may also be made by microarray analysis. Increasingly, microarray analysis is also being used to clarify breakpoints. Prenatal diagnosis is possible using amniocentesis or chorionic villus sampling.

Because Cowden syndrome can be difficult to diagnose, the exact prevalence is unknown; however, it probably occurs in at least 1 in 200,000 people.

A 2010 review of 211 patients (21 from one center, and the remaining 190 from the external literature) studied the risks for cancer and Lhermitte-Duclos disease in Cowden syndrome patients.

The cumulative lifetime (age 70 years) risks were 89% for any cancer diagnosis (95% confidence interval (CI) = 80%,95%), breast cancer [female] 81% (CI = 66%,90%), LDD 32% (CI = 19%,49%), thyroid cancer 21% (CI = 14%,29%), endometrial cancer 19% (CI = 10%,32%) and renal cancer 15% (CI = 6%,32%). A previously unreported increased lifetime risk for colorectal cancer was identified (16%, CI = 8%,24%). Male CS patients had fewer cancers diagnosed than female patients and often had cancers not classically associated with CS.

49,XXXXY syndrome is an extremely rare aneuploidic sex chromosomal abnormality. It occurs in approximately 1 out of 85,000 to 100,000 males.

The aneuploidy is thought to be caused by problems occurring during meiosis, either in the mother or in both the mother and father. Successive nondisjunctions have been observed in the mother of at least one patient.

The features of the syndrome likely arise due to failure of X-inactivation and the presence of multiple X chromosomes from the same parent causing problems with parental imprinting. In theory, X-inactivation should occur and leave only one X chromosome active in each cell. However, failure of this process has been observed in one individual studied. The reason for this is thought to be the presence of an unusually large, and imbalanced, number of X chromosomes interfering with the process.

49,XXXXX, also known as pentasomy X, penta X, or XXXXX syndrome, is a chromosomal aneuploidy where females have five X chromosomes rather than the normal two. It is unclear exactly how rare it is, but it appears to affect fewer than 1 in 100,000 women.

Diagnosis requires a neurological examination and neuroimaging can be helpful.

BVVL can be differentially diagnosed from similar conditions like Fazio-Londe syndrome and amyotrophic lateral sclerosis, in that those two conditions don't involve sensorineural hearing loss, while BVVL, Madras motor neuron disease, Nathalie syndrome, and Boltshauser syndrome do. Nathalie syndrome does not involve lower cranial nerve symptoms, so it can be excluded if those are present. If there is evidence of lower motor neuron involvement, Boltshauser syndrome can be excluded. Finally, if there is a family history of the condition, then BVVL is more likely than MMND, as MMND tends to be sporadic.

Genetic testing is able to identify genetic mutations underying BVVL.

The clinical course of BVVL can vary from one patient to another. There have been cases with progressive deterioration, deterioration followed by periods of stabilization, and deterioration with abrupt periods of increasing severity.

The syndrome has previously been considered to have a high mortality rate but the initial response of most patients to the Riboflavin protocol are very encouraging and seem to indicate a significantly improved life expectancy could be achievable. There are three documented cases of BVVL where the patient died within the first five years of the disease. On the contrary, most patients have survived more than 10 years after the onset of their first symptom, and several cases have survived 20–30 years after the onset of their first symptom.

Families with multiple cases of BVVL and, more generally, multiple cases of infantile progressive bulbar palsy can show variability in age of disease onset and survival. Dipti and Childs described such a situation in which a family had five children that had Infantile PBP. In this family, three siblings showed sensorineural deafness and other symptoms of BVVL at an older age. The other two siblings showed symptoms of Fazio-Londe disease and died before the age of two.

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).

Azoospermia is usually detected in the course of an infertility investigation. It is established on the basis of two semen analysis evaluations done at separate occasions (when the seminal specimen after centrifugation shows no sperm under the microscope) and requires a further work-up.

The investigation includes a history, a physical examination including a thorough evaluation of the scrotum and testes, laboratory tests, and possibly imaging. History includes the general health, sexual health, past fertility, libido, and sexual activity. Past exposure to a number of agents needs to be queried including medical agents like hormone/steroid therapy, antibiotics, 5-ASA inhibitors (sulfasalazine), alpha-blockers, 5 alpha-reductase inhibitors, chemotherapeutic agents, pesticides, recreational drugs (marijuana, excessive alcohol), and heat exposure of the testes. A history of surgical procedures of the genital system needs to be elicited. The family history needs to be assessed to look for genetic abnormalities.

Congenital absence of the vas deferens may be detectable on physical examination and can be confirmed by a transrectal ultrasound (TRUS). If confirmed genetic testing for cystic fibrosis is in order. Transrectal ultrasound can also assess azoospermia caused by obstruction, or anomalies related to obstruction of the ejaculatory duct, such as abnormalities within the duct itself, a median cyst of the prostate (indicating a need for cyst aspiration), or an impairment of the seminal vesicles to become enlarged or emptied.

Retrograde ejaculation is diagnosed by examining a postejaculatory urine for presence of sperm after making it alkaline and centifuging it.

Low levels of LH and FSH with low or normal testosterone levels are indicative of pretesticular problems, while high levels of gonadotropins indicate testicular problems. However, often this distinction is not clear and the differentiation between obstructive versus non-obstructive azoospermia may require a testicular biopsy. On the other hand, "In azoospermic men with a normal ejaculate volume, FSH serum level greater than two times the upper limit of the normal range is reliably diagnostic of dysfunctional spermatogenesis and, when found, a diagnostic testicular biopsy is usually unnecessary, although no consensus exists in this matter." But also, extremely high levels of FSH (>45 ID/mL) have been correlated with successful microdissection testicular sperm extraction.

Serum inhibin-B weakly indicates presence of sperm cells in the testes, raising chances for successfully achieving pregnancy through testicular sperm extraction (TESE), although the association is not very substantial, having a sensitivity of 0.65 (95% confidence interval [CI]: 0.56–0.74) and a specificity of 0.83 (CI: 0.64–0.93) for prediction the presence of sperm in the testes in non-obstructive azoospermia.

Seminal plasma proteins TEX101 and ECM1 were recently proposed for the differential diagnosis of azoospermia forms and subtypes, and for prediction of TESE outcome. Mount Sinai Hospital, Canada started clinical trial to test this hypothesis in 2016.

It is recommended that men primary hypopituitarism may be linked to a genetic cause, a genetic evaluation is indicated in men with azoospermia due to primary hypopituitarism. Azoospermic men with testicular failure are advised to undergo karyotype and Y-micro-deletion testing.

When surgery is indicated, the choice of treatment is based on the classification. Table 4 shows the treatment of cleft hand divided into the classification of Manske and Halikis.

Techniques described by Ueba, Miura and Komada and the procedure of Snow-Littler are guidelines; since clinical and anatomical presentation within the types differ, the actual treatment is based on the individual abnormality.

Table 4: Treatment based on the classification of Manske and Halikis

The timing of surgical interventions is debatable. Parents have to decide about their child in a very vulnerable time of their parenthood. Indications for early treatment are progressive deformities, such as syndactyly between index and thumb or transverse bones between the digital rays. Other surgical interventions are less urgent and can wait for 1 or 2 years.