Tests are either conducted at birth, or later in early childhood via: fluorescence in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA), array comparative genomic hybridization (aCGH), and EHMT1 sequencing.

FISH is a screening test that uses multicolour probes or comparative genomic hybridization to find any chromosome irregularities in a genome. It can be used for gene mapping, detecting aneuploidy, locating tumours etc. The multicolour probes attach to a certain DNA fragment. MLPA is a test that finds and records DNA copy change numbers through the use of PCR. MLPA can be used to detect tumours in the glial cells of the brain, as well as chromosomal abnormalities. Array-based comparative genomic hybridization (aCGH) tracks chromosome deletions and or amplifications using fluorescent dyes on genomic sequences of DNA samples. The DNA samples (which are 25-80 base pairs in length) are then placed on slides to be observed under microscope. Lastly, EHMT1 sequencing is a process in which a single-strand of DNA from the EHMT1 gene is removed, and DNA polymerase is added in order to synthesize complementary strands. In turn, this allows scientists to map out a person's DNA sequence allowing for a diagnosis to be made.

1. Clinical Genetics and Genetic Testing

Genetic testing is necessary to confirm the diagnosis of PMS. A prototypical terminal deletion of 22q13 can be uncovered by karyotype analysis, but many terminal and interstitial deletions are too small to detect with this method. Chromosomal microarray should be ordered in children with suspected developmental delays or ASD. Most cases will be identified by microarray; however, small variations in genes might be missed. The falling cost for whole exome sequencing may replace DNA microarray technology for candidate gene evaluation. Biological parents should be tested with fluorescence "in situ" hybridization (FISH) to rule out balanced translocations or inversions. Balanced translocation in a parent increases the risk for recurrence and heritability within families (figure 3).

Clinical genetic evaluations and dysmorphology exams should be done to evaluate growth, pubertal development, dysmorphic features (table 1) and screen for organ defects (table 2)

2. Cognitive and Behavioral Assessment

All patients should undergo comprehensive developmental, cognitive and behavioral assessments by clinicians with experience in developmental disorders. Cognitive evaluation should be tailored for individuals with significant language and developmental delays. All patients should be referred for specialized speech/language, occupational and physical therapy evaluations.

3. Neurological Management

Individuals with PMS should be followed by a pediatric neurologist regularly to monitor motor development, coordination and gait, as well as conditions that might be associated with hypotonia. Head circumference should be performed routinely up until 36 months. Given the high rate of seizure disorders (up to 41% of patients) reported in the literature in patients with PMS and its overall negative impact on development, an overnight video EEG should be considered early to rule out seizure activity. In addition, a baseline structural brain MRI should be considered to rule out the presence of structural abnormalities.

4. Nephrology

All patients should have a baseline renal and bladder ultrasonography and a voiding cystourethrogram should be considered to rule out structural and functional abnormalities. Renal abnormalities are reported in up to 38% of patients with PMS. Vesicouretral reflux, hydronephrosis, renal agenesis, dysplasic kidney, polycystic kidney and recurrent urinary tract infections have all been reported in patients with PMS.

5. Cardiology

Congenital heart defects (CHD) are reported in samples of children with PMS with varying frequency (up to 25%)(29,36). The most common CHD include tricuspid valve regurgitation, atrial septal defects and patent ductus arteriousus. Cardiac evaluation, including echocardiography and electrocardiogram, should be considered.

6. Gastroenterology

Gastrointestinal symptoms are common in individuals with PMS. Gastroesophageal reflux, constipation, diarrhea and cyclic vomiting are frequently described.

Table 3: Clinical Assessment Recommendations in Phelan McDermid Syndrome.

Diagnosis of 22q11.2 deletion syndrome can be difficult due to the number of potential symptoms and the variation in phenotypes between individuals. It is suspected in patients with one or more signs of the deletion. In these cases a diagnosis of 22q11.2DS is confirmed by observation of a deletion of part of the long arm (q) of chromosome 22, region 1, band 1, sub-band 2. Genetic analysis is normally performed using fluorescence "in situ" hybridization (FISH), which is able to detect microdeletions that standard karyotyping (e.g. G-banding) miss. Newer methods of analysis include Multiplex ligation-dependent probe amplification assay (MLPA) and quantitative polymerase chain reaction (qPCR), both of which can detect atypical deletions in 22q11.2 that are not detected by FISH. qPCR analysis is also quicker than FISH, which can have a turn around of 3 to 14 days.

A 2008 study of a new high-definition MLPA probe developed to detect copy number variation at 37 points on chromosome 22q found it to be as reliable as FISH in detecting normal 22q11.2 deletions. It was also able to detect smaller atypical deletions that are easily missed using FISH. These factors, along with the lower expense and easier testing mean that this MLPA probe could replace FISH in clinical testing.

Genetic testing using BACs-on-Beads has been successful in detecting deletions consistent with 22q11.2DS during prenatal testing. Array-comparative genomic hybridization (array-CGH) uses a large number of probes embossed in a chip to screen the entire genome for deletions or duplications. It can be used in post and pre-natal diagnosis of 22q11.2.

Fewer than 5% of individuals with clinical symptoms of the 22q11.2 deletion syndrome have normal routine cytogenetic studies and negative FISH testing. In these cases, atypical deletions are the cause. Some cases of 22q11.2 deletion syndrome have defects in other chromosomes, notably a deletion in chromosome region 10p14.

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.

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.

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.

Due to its recent discovery, there are currently no existing treatments for Kleefstra syndrome.

While no cure for MDS is available yet, many complications associated with this condition can be treated, and a great deal can be done to support or compensate for functional disabilities. Because of the diversity of the symptoms, it can be necessary to see a number of different specialists and undergo various examinations, including:

- Developmental evaluation

- Cardiologists evaluation

- Otolaryngology

- Treatment of seizures

- Urologic evaluation

- Genetic counseling-balanced chromosomal translocation should be excluded in a parents with an affected child are planning another pregnancy, so parents with affected children should visit a genetic counselor.

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 the variability of this disease is so great and the way that it reveals itself could be multi-faceted; once diagnosed, a multidisciplinary team is recommended to treat the disease and should include a craniofacial surgeon, ophthalmologist, pediatrician, pediatric urologist, cardiologist, pulmonologist, speech pathologist, and a medical geneticist. Several important steps must be followed, as well.

- Past medical history

- Physical examination with special attention to size and measurements of facial features, palate, heart, genitourinary system and lower respiratory system

- Eye evaluation

- Hypospadias assessment by urologist

- Laryngoscopy and chest x-ray for difficulties with breathing/swallowing

- Cleft lip/palate assessment by craniofacial surgeon

- Assessment of standard age developmental and intellectual abilities

- Anal position assessment

- Echocardiogram

- Cranial imaging

Many surgical repairs may be needed, as assessed by professionals. Furthermore, special education therapies and psychoemotional therapies may be required, as well. In some cases, antireflux drugs can be prescribed until risk of breathing and swallowing disorders are removed. Genetic counseling is highly advised to help explain who else in the family may be at risk for the disease and to help guide family planning decisions in the future.

Because of its wide variability in which defects will occur, there is no known mortality rate specifically for the disease. However, the leading cause of death for people with Opitz G/BBB syndrome is due to infant death caused by aspiration due to esophageal, pharyngeal or laryngeal defects.

Fortunately, to date there are no factors that can increase the expression of symptoms of this disease. All abnormalities and symptoms are present at birth.

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.

Suspicion of a chromosome abnormality is typically raised due to the presence of developmental delays or birth defects. Diagnosis of 18p- 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 of chorionic villus sampling.

Since the symptoms caused by this disease are present at birth, there is no “cure.” The best cure that scientists are researching is awareness and genetic testing to determine risk factors and increase knowledgeable family planning. Prevention is the only option at this point in time for a cure.

Diagnosis is based on the distinctive cry and accompanying physical problems. These common symptoms are quite easily observed in infants. Affected children are typically diagnosed by a doctor or nurse at birth. Genetic counseling and genetic testing may be offered to families with individuals who have cri du chat syndrome. Prenatally the deletion of the cri du chat related region in the p arm of chromosome 5 can be detected from amniotic fluid or chorionic villi samples with BACs-on-Beads technology. G-banded karyotype of a carrier is also useful. Children may be treated by speech, physical and occupational therapists. Heart abnormalities often require surgical correction.

SMS is usually confirmed by blood tests called chromosome (cytogenetic) analysis and utilize a technique called FISH (fluorescent in situ hybridization). The characteristic micro-deletion was sometimes overlooked in a standard FISH test, leading to a number of people with the symptoms of SMS with negative results.

The recent development of the FISH for 17p11.2 deletion test has allowed more accurate detection of this deletion. However, further testing is required for variations of Smith–Magenis syndrome that are caused by a mutation of the "RAI1" gene as opposed to a deletion.

Children with SMS are often given psychiatric diagnoses such as autism, attention deficit/hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), attention deficit disorder (ADD) and/or mood disorders.

At present, treatment for 18p- 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 18p- undergo routine screenings for hearing and vision problems.

Techniques used to diagnose this disorder are fluorescence in situ hybridization (FISH) and microarrays. FISH uses fluorescent dyes to visualize sections under a microscope, but some changes are too small to see. Microarray comparative genomic hybridization (array CGH) shows changes in small amounts DNA on chromosomes.

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 is based on clinical findings and can be confirmed by cytogenetic testing, when the deletion is in an average of 5 Mb (millions of base pairs). Nowadays is a common practice to run an aCHG (array chromosome hybridization genome) study on peripheral blood of the patient, in order to limit the extent of the loss of the genomic area, and the deleted genes.

The following should be taken into account when pronouncing a diagnosis for this condition:

Although 1p36 Deletion Syndrome can be debilitating in many ways, patients do respond to various treatments and therapies. These include the following:

American Sign Language: Because few individuals with Monosomy 1p36 develop complex speech, an alternate form of communication is critical to development. Most patients can learn basic signs to communicate their needs and wants. This also appears to reduce frustration and may reduce self-injurious tendencies. Children with hearing loss will often qualify for locally sponsored sign language classes.

Music Therapy: Music has been shown to aid children with 1p36 deletion in various developmental areas. It serves as an excellent auditory stimulus and can teach listening skills. Songs with actions help the child to develop coordination and motor skills.

Physical Therapy: Due to low muscle tone, patients with 1p36 Deletions take a great deal of time to learn to roll over, sit up, crawl and walk. However, regular physical therapy has shown to shorten the length of time needed to achieve each of those developmental milestones.

Occupational Therapy can be helpful to help children with oral motor and feeding difficulties (including dysphagia and transitioning to solid foods) as well as developmental delays in motor, social and sensory domains.

Treatment of cause: Due to the genetic cause, no treatment of the cause is possible.

Treatment of manifestations: routine treatment of ophthalmologic, cardiac, and neurologic findings; speech, occupational, and physical therapies as appropriate; specialized learning programs to meet individual needs; antiepileptic drugs or antipsychotic medications as needed.

Surveillance: routine pediatric care; routine developmental assessments; monitoring of specific identified medical issues.

At present, treatment for proximal 18q- is symptomatic, meaning that the focus is on treating the signs and symptoms of the condition as they arise.

There has been no treatment discovered for Jacobsen Syndrome until now but the Symptoms can be treated. 56% of children with Jacobsen Syndrome have congenital heart problems to keep them in check a baseline evaluation can be made by a paediatric cardiologist by carrying out an electrocardiogram or echocardiogram. Any problems that are found can be treated then.

Almost all affected children are born with a bleeding disorder, monthly CBT may help ease the problem. Consecutively Platelet transfusion and ddAVP can be carried out. Medication that interferes with platelet count should be avoided and oral contraceptive therapy may be considered for women with heavy bleeding during menses.

Children affected with Jacobsen Syndrome have severe to Moderate intellectual disabilities and cognitive impairment. An evaluation by a neuropsychologist or a behaviour specialist like a Psychiatrist or Psychologist can be performed, including brain imaging like MRI or ERP. Then as deemed appropriate intervention programs can be carried through. Music therapy is very beneficial for language development. According to the age, befitting vision and hearing test can aid in fixing problems related cognition. For problems related to behaviour like ADHD, medication or therapy would be required but a combination of both is more effective. An ophthalmologist should be consulted to treat the eye defects. Play and interactive games encourage the child to speak. Habilitiation in children should begin at an early age. A habilitation team includes professionals with special expertise in how disability affects everyday life, health and development. The entire family is supported to help the affected children and their families adjust better.

22q11.2 deletion syndrome was estimated to affect between one in 2000 and one in 4000 live births. This estimate is based on major birth defects and may be an underestimate, because some individuals with the deletion have few symptoms and may not have been formally diagnosed. It is one of the most common causes of mental retardation due to a genetic deletion syndrome.

The prevalence of 22q11.2DS has been expected to rise because of multiple reasons: (1) Thanks to surgical and medical advances, an increasing number of people are surviving heart defects associated with the syndrome. These individuals are in turn having children. The chances of a 22q11.2DS patient having an affected child is 50% for each pregnancy; (2) Parents who have affected children, but who were unaware of their own genetic conditions, are now being diagnosed as genetic testing become available; (3) Molecular genetics techniques such as FISH (fluorescence in situ hybridization) have limitations and have not been able to detect all 22q11.2 deletions. Newer technologies have been able to detect these atypical deletions.

Recently, the syndrome has been estimated to affect up to one in 2000 live births. Testing for 22q11.2DS in over 9500 pregnancies revealed a prevalence rate of 1/992.