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.

Medical management of children with Trisomy 13 is planned on a case-by-case basis and depends on the individual circumstances of the patient. Treatment of Patau syndrome focuses on the particular physical problems with which each child is born. Many infants have difficulty surviving the first few days or weeks due to severe neurological problems or complex heart defects. Surgery may be necessary to repair heart defects or cleft lip and cleft palate. Physical, occupational, and speech therapy will help individuals with Patau syndrome reach their full developmental potential. Surviving children are described as happy and parents report that they enrich their lives. The cited study grouped Edwards syndrome, which is sometimes survivable beyond toddlerhood, along with Patau, hence the median age of 4 at the time of data collection.

There is no known cure for microcephaly. Treatment is symptomatic and supportive.

Currently, the most common form of treatment for SLOS involves dietary cholesterol supplementation. Anecdotal reports indicate that this has some benefits; it may result in increased growth, lower irritability, improved sociability, less self-injurious behaviour, less tactile defensiveness, fewer infections, more muscle tone, less photosensitivity and fewer autistic behaviours. Cholesterol supplementation begins at a dose of 40–50 mg/kg/day, increasing as needed. It is administered either through consuming foods high in cholesterol (eggs, cream, liver), or as purified food grade cholesterol. Younger children and infants may require tube feeding. However, dietary cholesterol does not reduce the levels of 7DHC, cannot cross the blood–brain barrier, and does not appear to improve developmental outcomes. One empirical study found that cholesterol supplementation did not improve developmental delay, regardless of the age at which it began. This is likely because most developmental delays stem from malformations of the brain, which dietary cholesterol cannot ameliorate due to its inability to cross the blood–brain barrier.

HMG-CoA reductase inhibitors have been examined as treatment for SLOS. Given that this catalyzes the rate-limiting step in cholesterol synthesis, inhibiting it would reduce the buildup of toxic metabolites such as 7DHC. Simvastatin is a known inhibitor of HMG-CoA reductase, and most importantly is able to cross the blood–brain barrier. It has been reported to decrease the levels of 7DHC, as well as increase the levels of cholesterol. The increased cholesterol levels are due to simvastatin's effect on the expression of different genes. Simvastatin increases the expression of "DHCR7", likely leading to increased activity of DHCR7. It has also been shown to increase the expression of other genes involved in cholesterol synthesis and uptake. However, these benefits are dependent on the amount of residual cholesterol synthesis. Because some individuals possess less severe mutations and demonstrate some amount of DCHR7 activity, these people benefit the most from simvastatin therapy as they still have a partially functioning enzyme. For individuals that show no residual DCHR7 activity, such as those homozygous for null alleles or mutations, simvastatin therapy may actually be toxic. This highlights the importance of identifying the specific genotype of the SLOS patient before administering treatment. It is still unknown if simvastatin will improve the behavioural or learning deficits in SLOS.

Treatment of 3-M syndrome is aimed at the specific symptoms presented in each individual. With the various symptoms of this disorder being properly managed and affected individuals having normal mental development, 3-M syndrome is not a life - threatening condition and individuals are able to lead a near normal life with normal life expectancy.

Treatment may involve the coordinated efforts of many healthcare professionals, such as pediatricians, orthopedists, dentists and/or other specialists depending on the symptoms.

- Possible management options for short stature are surgical bone lengthening or growth hormone therapy.

- Orthopedic techniques and surgery may be used to treat certain skeletal abnormalities.

- Plastic surgery may also be performed on individuals to help correct certain cranio-facial anomalies.

- Individuals with dental abnormalities may undergo corrective procedures such as braces or oral surgeries.

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.

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.

Most fetuses with triploidy do not survive to birth, and those that do usually pass within days. As there is no treatment for Triploidy, palliative care is given if a baby survives to birth. If Triploidy is diagnosed during the pregnancy, termination is often offered as an option due to the additional health risks for the mother (preeclampsia, a life-threatening condition, or choriocarcinoma, a type of cancer). Should a mother decide to carry until term or until a spontaneous miscarriage occurs, doctors will monitor her closely in case either condition develops.

Mosaic triploidy has an improved prognosis, but affected individuals have moderate to severe cognitive disabilities.

Pregnant mothers are advised to take folic acid supplements to reduce risk of iniencephaly by up to 70%. Pregnant mothers are also advised not to take antiepileptic drugs, diuretics, antihistamines, and sulfa drugs, all of which have been associated with increased risk for neural tube defects.

Affected individuals have a somewhat shortened lifespan. The maximum described lifespan is 67 years. Adults with 13q deletion syndrome often need support services to maintain their activities of daily living, including adult day care services or housing services.

There is no standard treatment for hydranencephaly. Treatment is symptomatic and supportive. Hydrocephalus may be treated with surgical treatment of a shunt, which often grants a much better prognosis and greater quality of life.

The prognosis for children with hydranencephaly is generally quite poor. Death often occurs in the first year of life, but other children may live several years.

Medical text identifies that hydranencephalic children simply have only their brain stem function remaining, thus leaving formal treatment options as symptomatic and supportive. Severe hydrocephalus causing macrocephaly, a larger than average head circumference, can easily be managed by placement of a shunt and often displays a misdiagnosis of another lesser variation of cephalic condition due to the blanketing nature of hydrocephalus. Plagiocephaly, the asymmetrical distortion of the skull, is another typical associated condition that is easily managed through positioning and strengthening exercises to prevent torticollis, a constant spasm or extreme tightening of the neck muscles.

Because newborns can breathe only through their nose, the main goal of postnatal treatment is to establish a proper airway. Primary surgical treatment of FND can already be performed at the age of 6 months, but most surgeons wait for the children to reach the age of 6 to 8 years. This decision is made because then the neurocranium and orbits have developed to 90% of their eventual form. Furthermore, the dental placement in the jaw has been finalized around this age.

Since newborns with iniencephaly so rarely survive past childbirth, a standard treatment does not exist.

Patients with PDE do not respond to anticonvulsant medications, but seizures rapidly cease with therapeutic intravenous doses of Vitamin B6 and remission from seizures are often maintained on daily therapeutic doses of Vitamin B6. An optimal dose has not yet been established, but doses of 50–100 mg/day or 15–30 mg/kg/day have been proposed. Importantly, excessive doses of vitamin B6 can result in irreversible neurological damage, and therefore several guidelines recommend 500 mg per day as the maximal daily dose.

Despite remission of seizure activity with vitamin B6 supplementation, intellectual disability is frequently seen in patients with PDE. Because the affected enzyme antiquitin is involved in the cerebral lysine degradation pathway, lysine restriction as an additional treatment modality has recently been explored. Studies have been published which demonstrate potential for improved biomarkers, development, and behavior in patients treated with lysine restriction in addition to pyridoxine supplementation. In trial, lysine restriction of 70–100 mg/kg/day in children less than 1 year of age, 45–80 mg/kg/day in children between 1–7 years of age, and 20–45 mg/kg/day in children older than 7 years of age were prescribed. Despite the potential of additional benefit from lysine restriction, vitamin B6 supplementation remains the main-stay of treatment given lack of studies thus far demonstrating the safety and efficacy of lysine restriction for this purpose.

Structural nasal deformities are corrected during or shortly after the facial bipartition surgery. In this procedure, bone grafts are used to reconstruct the nasal bridge. However, a second procedure is often needed after the development of the nose has been finalized (at the age of 14 years or even later).

Secondary rhinoplasty is based mainly on a nasal augmentation, since it has been proven better to add tissue to the nose than to remove tissue. This is caused by the minimal capacity of contraction of the nasal skin after surgery.

In rhinoplasty, the use of autografts (tissue from the same person as the surgery is performed on) is preferred. However, this is often made impossible by the relative damage done by previous surgery. In those cases, bone tissue from the skull or the ribs is used. However, this may give rise to serious complications such as fractures, resorption of the bone, or a flattened nasofacial angle.

To prevent these complications, an implant made out of alloplastic material could be considered. Implants take less surgery time, are limitlessly available and may have more favorable characteristics than autografts. However, possible risks are rejection, infection, migration of the implant, or unpredictable changes in the physical appearance in the long term.

At the age of skeletal maturity, orthognathic surgery may be needed because of the often hypoplastic maxilla. Skeletal maturity is usually reached around the age of 13 to 16. Orthognathic surgery engages in diagnosing and treating disorders of the face and teeth- and jaw position.

Currently, research is focusing on identifying the role of the genes on 18p in causing the signs and symptoms associated with deletions of 18p. This will ultimately enable predictive genotyping.

TGIF-Mutations and deletions of this gene have been associated with holoprosencephaly. Penetrance is incomplete, meaning that a deletion of one copy of this gene is not in and of itself sufficient to cause holoprosencephaly. Ten to fifteen percent of people with 18p- have holoprosencephaly, suggesting that other genetic and environmental facts play a role in the etiology of holoprosencephaly in these individuals.

More than 80% of children with Patau syndrome die within the first year of life. Children with the mosaic variation are usually affected to a lesser extent. In a retrospective Canadian study of 174 children with trisomy 13, median survival time was 12.5 days. One and ten year survival was 19.8% and 12.9% respectively.

HPE is not a condition in which the brain deteriorates over time. Although serious seizure disorders, autonomic dysfunction, complicated endocrine disorders and other life-threatening conditions may sometimes be associated with HPE, the mere presence of HPE does not mean that these serious problems will occur or develop over time without any previous indication or warning. These abnormalities are usually recognized shortly after birth or early in life and only occur if areas of the brain controlling those functions are fused, malformed or absent.

Prognosis is dependent upon the degree of fusion and malformation of the brain, as well as other health complications that may be present.

The more severe forms of encephalopathy are usually fatal. This disorder consists of a spectrum of defects, malformations and associated abnormalities. Disability is based upon the degree in which the brain is affected. Moderate to severe defects may cause mental retardation, spastic quadriparesis, athetoid movements, endocrine disorders, epilepsy and other serious conditions; mild brain defects may only cause learning or behavior problems with few motor impairments.

Seizures may develop over time with the highest risk before 2 years of age and the onset of puberty. Most are managed with one medication or a combination of medications. Typically, seizures that are difficult to control appear soon after birth, requiring more aggressive medication combinations/doses.

Most children with HPE are at risk of having elevated blood sodium levels during moderate-severe illnesses, that alter fluid intake/output, even if they have no previous diagnosis of diabetes insipidus or hypernatremia.

MRI will help with the diagnosis of structural abnormality of the brain. Genetic testing may also be pursued.

Vestronidase alfa-vjbk (Mepsevii) is the only drug approved by U.S. Food and Drug Administration for the treatment of pediatric and adult patients.

Ethmocephaly is a type of cephalic disorder caused by holoprosencephaly. Ethmocephaly is the least common facial anomaly. It consists of a proboscis separating narrow-set eyes with an absent nose and microphthalmia (abnormal smallness of one or both eyes). Cebocephaly, another facial anomaly, is characterized by a small, flattened nose with a single nostril situated below incomplete or underdeveloped closely set eyes.

The least severe in the spectrum of facial anomalies is the median cleft lip, also called premaxillary agenesis.

Although the causes of most cases of holoprosencephaly remain unknown, some may be due to dominant or chromosome causes. Such chromosomal anomalies as trisomy 13 and trisomy 18 have been found in association with holoprosencephaly, or other neural tube defects. Genetic counseling and genetic testing, such as amniocentesis, is usually offered during a pregnancy if holoprosencephaly is detected. The recurrence risk depends on the underlying cause. If no cause is identified and the fetal chromosomes are normal, the chance to have another pregnancy affected with holoprosencephaly is about 6%.

There is no treatment for holoprosencephaly and the prognosis for individuals with the disorder is poor. Most of those who survive show no significant developmental gains. For children who survive, treatment is symptomatic. It is possible that improved management of diabetic pregnancies may help prevent holoprosencephaly, however there is no means of primary prevention.

Numerous possible risk factors have been identified, including gestational diabetes, transplacental infections (the "TORCH complex"), first trimester bleeding, and a history of miscarriage. As well, the disorder is found twice as often in female babies. However, there appears to be no correlation between HPE and maternal age.

There is evidence of a correlation between HPE and the use of various drugs classified as being potentially unsafe for pregnant and lactating mothers. These include insulin, birth control pills, aspirin, lithium, thorazine, retinoic acid, and anticonvulsants. There is also a correlation between alcohol consumption and HPE, along with nicotine, the toxins in cigarettes and toxins in cigarette smoke when used during pregnancy.

Plasma and cerebrospinal fluid levels of pipecolic acid are frequently elevated in patients with PDE, though it is a non-specific biomarker. α-aminodipic semialdehyde is elevated in urine and plasma and is a more specific biomarker for PDE. Improvements in these biomarkers have been reported with the implementation of a lysine-restricted diet. Initial studies evaluating the safety and efficacy of lysine restriction evaluated developmental and cognitive outcomes by age-appropriate tests and parental observations.

Recent research has been focused on studying large series of cases of 3-M syndrome to allow scientists to obtain more information behind the genes involved in the development of this disorder. Knowing more about the underlying mechanism can reveal new possibilities for treatment and prevention of genetic disorders like 3-M syndrome.

- One study looks at 33 cases of 3M syndrome, 23 of these cases were identified as CUL7 mutations: 12 being homozygotes and 11 being heterozygotes. This new research shows genetic heterogeneity in 3M syndrome, in contrast to the clinical homogeneity. Additional studies are still ongoing and will lead to the understanding of this new information.

- This study provides more insight on the three genes involved in 3M syndrome and how they interact with each other in normal development. It lead to the discovery that the CUL7, OBS1, and CCDC8 form a complex that functions to maintain microtubule and genomic integrity.