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.

Bloom syndrome is diagnosed using any of three tests - the presence of quadriradial (Qr, a four-armed chromatid interchange) in cultured blood lymphocytes, and/or the elevated levels of Sister chromatid exchange in cells of any type, and/or the mutation in the BLM gene. The US Food and Drug Administration (FDA) announced on February 19, 2015 that they have authorized marketing of a direct-to-consumer genetic test from 23andMe. The test is designed to identify healthy individuals who carry a gene that could cause Bloom Syndrome in their offspring.

Most affected people have a stable clinical course but are often transfusion dependent.

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.

A prenatal diagnostic is possible and very reliable when mother is carrier of the syndrome. First, it's necessary to determine the fetus' sex and then study X-chromosomes. In both cases, the probability to transfer the X-chromosome affected to the descendants is 50%. Male descendants who inherit the affected chromosome will express the symptoms of the syndrome, but females who do will be carriers.

Potocki–Shaffer syndrome can be detected through array comparative genomic hybridization (aCGH).

Some symptoms can be managed with drug therapy, surgery and rehabilitation, genetic counselling, and palliative care.

Bloom syndrome has no specific treatment; however, avoiding sun exposure and using sunscreens can help prevent some of the cutaneous changes associated with photo-sensitivity. Efforts to minimize exposure to other known environmental mutagens are also advisable.

A diagnosis can be made on the combination of clinical features. This can then be confirmed by gene sequencing.

MORM syndrome is a genetic disorder obtained through inheritance. The main method for testing individuals showing symptoms of MORM syndrome is sequence analysis of the entire coding region. When performing a sequence analysis of the entire coding region the gene INNP5E is targeted. Sequence analysis is the biotechnological process in which the structure and sequence of DNA, RNA, or protein sequence is determined through the use of technology. The sequence can then be analyzed to determine mutations or abnormalities in that particular region. When testing for MORM syndrome, sequence analysis of the region of the genome which contains the gene INPP5E is targeted and examined to look for mutations.

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.

Lenalidomide has activity in 5q- syndrome and is FDA approved for red blood cell (RBC) transfusion-dependent anemia due to low or intermediate-1 (int-1) risk myelodysplastic syndrome (MDS) associated with chromosome 5q deletion with or without additional cytogenetic abnormalities. There are several possible mechanisms that link the haploinsufficiency molecular lesions with lenalidomide sensitivity.

A review from 2000 stated that life expectancy was reduced because of a tendency to develop cancer relatively early as well as deaths due to infections related to immunodeficiency.

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.

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

There is no treatment for NBS, however in those with agammaglobulinemia, intravenous immunoglobulin may be started. Prophylactic antibiotics are considered to prevent urinary tract infections as those with NBS often have congenital kidney malformations. In the treat of malignancies radiation, alkylating antineoplastic agents, and epipodophyllotoxins are not used, and methotrexate can be used with caution and, the dose should be limited. Bone marrow transplants and hematopoietic stem cells transplants are also considered in the treatment of NBS. The supplementation of Vitamin E is also recommended. A ventriculoperitoneal shunt can be placed in patients with hydrocephaly, and surgical intervention of congenital deformities is also attempted.

Though only definitively diagnosable by genetic sequence testing, including a G band analysis, ATR-16 syndrome may be diagnosed from its constellation of symptoms. It must be distinguished from ATR-X syndrome, a very similar disease caused by a mutation on the X chromosome, and cases of alpha-thalassemia that co-occur with intellectual disabilities with no underlying genetic relationship.

Diagnosis is usually based on clinical findings, although fetal chromosome testing will show trisomy 13. While many of the physical findings are similar to Edwards syndrome there are a few unique traits, such as polydactyly. However, unlike Edwards syndrome and Down syndrome, the quad screen does not provide a reliable means of screening for this disorder. This is due to the variability of the results seen in fetuses with Patau.

The diagnosis of A-T is usually suspected by the combination of neurologic clinical features (ataxia, abnormal control of eye movement, and postural instability) with telangiectasia and sometimes increased infections, and confirmed by specific laboratory abnormalities (elevated alpha-fetoprotein levels, increased chromosomal breakage or cell death of white blood cells after exposure to X-rays, absence of ATM protein in white blood cells, or mutations in each of the person’s ATM genes).

A variety of laboratory abnormalities occur in most people with A-T, allowing for a tentative diagnosis to be made in the presence of typical clinical features. Not all abnormalities are seen in all patients. These abnormalities include:

- Elevated and slowly increasing alpha-fetoprotein levels in serum after 2 years of age

- Immunodeficiency with low levels of immunoglobulins (especially IgA, IgG subclasses, and IgE) and low number of lymphocytes in the blood

- Chromosomal instability (broken pieces of chromosomes)

- Increased sensitivity of cells to x-ray exposure (cells die or develop even more breaks and other damage to chromosomes)

- Cerebellar atrophy on MRI scan

The diagnosis can be confirmed in the laboratory by finding an absence or deficiency of the ATM protein in cultured blood cells, an absence or deficiency of ATM function (kinase assay), or mutations in both copies of the cell’s ATM gene. These more specialized tests are not always needed, but are particularly helpful if a child’s symptoms are atypical.

Treatments for ATR-16 syndrome depend on the symptoms experienced by any individual. Alpha thalassemia is usually self-limiting, but in some cases may require a blood transfusion or chelating treatment.

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.

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.

Emanuel Syndrome can be diagnosed with a karyotype, with FISH, or with a chromosomal microarray analysis. .

Chromosome instability syndromes are a group of inherited conditions associated with chromosomal instability and breakage. They often lead to an increased tendency to develop certain types of malignancies.

The following chromosome instability syndromes are known:

- Ataxia telangiectasia

- Ataxia telangiectasia-like disorder

- Bloom syndrome

- Fanconi anaemia

- Nijmegen breakage syndrome

Emanuel Syndrome does not have a cure, but individual symptoms may be treated. Assessments of individual systems, such as the cardiovascular, gastrointestinal, orthopedic, and neurological may be necessary to determine the extent of impairment and options for treatment.

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.