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.

Y chromosome microdeletion is currently diagnosed by extracting DNA from leukocytes in a man's blood sample, mixing it with some of the about 300 known genetic markers for sequence-tagged sites (STS) on the Y chromosome, and then using polymerase chain reaction amplification and gel electrophoresis in order to test whether the DNA sequence corresponding to the selected markers is present in the DNA.

Such procedures can test only the integrity of a tiny part of the overall 23 million base pair long Y chromosome, therefore the sensitivity of such tests depends on the choice and number of markers used. Present diagnostic techniques can only discover certain types of deletions and mutations on a chromosome and give therefore no complete picture of genetic causes of infertility. They can only demonstrate the presence of some defects, but not the absence of any possible genetic defect on the chromosome.

The gold standard test for genetic mutation, namely complete DNA sequencing of a patient's Y chromosome, is still far too expensive for use in epidemiologic research or even clinical diagnostics.

Microdeletions in the Y chromosome have been found at a much higher rate in infertile men than in fertile controls and the correlation found may still go up as improved genetic testing techniques for the Y chromosome are developed.

Much study has been focused upon the "azoospermia factor locus" (AZF), at Yq11. A specific partial deletion of AZFc called "gr/gr deletion" is significantly associated with male infertility among Caucasians in Europe and the Western Pacific region.

Additional genes associated with spermatogenesis in men and reduced fertility upon Y chromosome deletions include RBM, DAZ, SPGY, and TSPY.

Suspicion of a chromosome abnormality is typically raised due to the presence of developmental delays or birth defects. Diagnosis of ring 18 is usually made via 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 via amniocentesis or chorionic villus sampling.

Most individuals with this condition do not survive beyond childhood. Individuals with MDS usually die in infancy and therefore do not live to the age where they can reproduce and transmit MDS to their offspring.

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

The brain is usually grossly abnormal in outline when someone is diagnosed with Miller–Dieker syndrome. Only a few shallow sulci and shallow Sylvian fissures are seen; this takes on an hourglass or figure-8 appearance on the axial imaging. The thickness and measurement for a person without MDS is 3–4 mm. With MDS, a person's cortex is measured at 12–20 mm.

13q deletion syndrome can only be definitively diagnosed by genetic analysis, which can be done prenatally or after birth. Increased nuchal translucency in a first-trimester ultrasound may indicate the presence of 13q deletion.

Although LFS is usually suspected when intellectual disability and marfanoid habitus are observed together in a patient, the diagnosis of LFS can be confirmed by the presence of the p.N1007S missense mutation in the "MED12" gene.

Diagnosing Jacobsen Syndrome can be difficult in some cases because it is a rare chromosomal disorder. There are a variety of tests that can be carried out like karyotype, cardiac echocardiogram, a renal sonogram, a platelet count, blood count, a brain imaging study. Genetic testing can be carried out for diagnosis. In which chromosomes are stained to give a barcode like appearance and studied under the microscope which reveals the broken and deleted genes. It can also be diagnosed early in the prenatal stage if there are any abnormalities seen in the ultrasound. A simple assessment of the symptoms can be done to diagnose the Syndrome. A thorough physical examination could be carried out to assess the symptoms.

In the differential diagnosis of LFS, another disorder that exhibits some features and symptoms of LFS and is also associated with a missense mutation of "MED12" is Opitz-Kaveggia syndrome (FGS). Common features shared by both LFS and FGS include X-linked intellectual disability, hyperactivity, macrocephaly, corpus callosum agenesis and hypotonia. Notable features of FGS that have not been reported with LFS include excessive talkativness, consistent strength in socialization skills, imperforate anus (occlusion of the anus) and ocular hypertelorism (extremely wide-set eyes).

Whereas LFS is associated with missense mutation p.N1007S, FGS is associated with missense mutation p.R961W. As both disorders originate from an identical type of mutation in the same gene, while exhibiting similar, yet distinct characteristics; LFS and FGS are considered to be allelic. In the context of "MED12", this suggests that the phenotype of each disorder is related to the way in which their respective mutations alter the "MED12" sequence and its function.

Ring chromosome 14 syndrome is extremely rare, the true rate of occurrence is unknown (as it is "less than" 1 per 1,000,000), but there are at least 50 documented cases in the literature.

Diagnosis is achieved by examining the structure of the chromosomes through karyotyping; while once born, one can do the following to ascertain a diagnosis of the condition:

- MRI

- EEG

The ring 20 abnormality may be limited to as few as 5% of cells, so a screen for chromosomal mosaicism is critical. Newer array technology will not detect the ring chromosome and the standard metaphase chromosome analysis has been recommended. A karyotype analysis examining at least 50 cells should be requested to properly detect mosaicism.

Diagnosis of 48, XXXY is usually done by a standard karyotype. A karyotype is a chromosomal analysis in which a full set of chromosomes can be seen for an individual. The presence of the additional 2 X chromosomes on the karyotype are indicative of XXXY syndrome.

Another way to diagnosis 48, XXXY is by chromosomal microarray showing the presence of extra X chromosomes. Chromosomal microarray (CMA) is used to detect extra or missing chromosomal segments or whole chromosomes. CMA uses microchip-based testing to analyze many pieces of DNA. Males with 48, XXXY are diagnosed anywhere from before birth to adulthood as a result of the range in the severity of symptoms. The age range at diagnosis is likely due to the fact that XXXY is a rare syndrome, and does not cause as extreme phenotypes as other variants of Klinefelter syndrome (such as XXXXY).

Diagnostic testing could also be done via blood samples. Elevated levels of follicle stimulating hormone, luteinizing hormone, and low levels of testosterone can be indicative of this syndrome.

Identification of 45,X/46,XY karyotype has significant clinical implications due to known effects on growth, hormonal balance, gonadal development and histology. 45,X/46,XY is diagnosed by examining the chromosomes in a blood sample.

The age of diagnosis varies depending on manifestations of disease prompting reason for cytogenetic testing. Many patients are diagnosed prenatally due to fetal factors (increased nuchal fold, or abnormal levels of serum), maternal age or abnormal ultrasounds, while others will be diagnosed postnatal due to external genital malformation. It is not uncommon for patients to be diagnosed later in life due to short stature or delayed puberty, or a combination of both.

45,X/46,XY mosaicism can be detected prenatally through amniocentesis however, it was determined that the proportion of 45,X cells in the amniotic fluid cannot predict any phenotypic outcomes, often making prenatal genetic counselling difficult.

Due to the wide range of genetic disorders that are presently known, diagnosis of a genetic disorder is widely varied and dependent of the disorder. Most genetic disorders are diagnosed at birth or during early childhood, however some, such as Huntington's disease, can escape detection until the patient is well into adulthood.

The basic aspects of a genetic disorder rests on the inheritance of genetic material. With an in depth family history, it is possible to anticipate possible disorders in children which direct medical professionals to specific tests depending on the disorder and allow parents the chance to prepare for potential lifestyle changes, anticipate the possibility of stillbirth, or contemplate termination. Prenatal diagnosis can detect the presence of characteristic abnormalities in fetal development through ultrasound, or detect the presence of characteristic substances via invasive procedures which involve inserting probes or needles into the uterus such as in amniocentesis.

Patients have an essentially normal life expectancy but require regular medical follow-up.

Not all genetic disorders directly result in death, however there are no known cures for genetic disorders. Many genetic disorders affect stages of development such as Down syndrome. While others result in purely physical symptoms such as muscular dystrophy. Other disorders, such as Huntington's disease show no signs until adulthood. During the active time of a genetic disorder, patients mostly rely on maintaining or slowing the degradation of quality of life and maintain patient autonomy. This includes physical therapy, pain management, and may include a selection of alternative medicine programs.

A karyotype is done to diagnose XXYY syndrome. Treatment consists of medications, behavioral therapies and intensive community support.

Although there is no cure for 13q deletion syndrome, symptoms can be managed, usually with the involvement of a neurologist, rehabilitation physician, occupational therapist, physiotherapist, psychotherapist, nutritionist, special education professional, and/or speech therapist. If the affected child's growth is particularly slow, growth hormone treatment can be used to augment growth. Plastic surgeries can repair cleft palates, and surgical repair or monitoring by a pediatric cardiologist can manage cardiac defects. Some skeletal, neurological, genitourinary, gastrointestinal, and ophthalmic abnormalities can be definitively treated with surgery. Endocrine abnormalities can often be managed medically. Special educators, speech and occupational therapists, and physiotherapists can help a child develop skills in and out of school.

47,XYY syndrome is not usually diagnosed until learning issues are present. The syndrome is diagnosed in an increasing number of children prenatally by amniocentesis and chorionic villus sampling in order to obtain a chromosome karyotype, where the abnormality can be observed.

It is estimated that only 15–20% of children with 47,XYY syndrome are diagnosed within their lifetime. Of these, approximately 30% are diagnosed prenatally. For the rest of those diagnosed after childbirth, around half are diagnosed during childhood or adolescence due to developmental delays or learning difficulties. The rest are diagnosed for a variety of reasons including a small percentage due to fertility problems (5%).

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.

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.