Fragile X syndrome is the most translated neurodevelopmental disorder under study. The increased understanding of the molecular mechanisms of disease in FXS has led to the development of therapies targeting the affected pathways. Evidence from mouse models shows that mGluR5 antagonists (blockers) can rescue dendritic spine abnormalities and seizures, as well as cognitive and behavioral problems, and may show promise in the treatment of FXS. Two new drugs, AFQ-056 (mavoglurant) and dipraglurant, as well as the repurposed drug fenobam are currently undergoing human trials for the treatment of FXS. There is also early evidence for the efficacy of arbaclofen, a GABA agonist, in improving social withdrawal in individuals with FXS and ASD.

In addition, there is evidence from mouse models that minocycline, an antibiotic used for the treatment of acne, rescues abnormalities of the dendrites. An open trial in humans has shown promising results, although there is currently no evidence from controlled trials to support its use.

The first complete DNA sequence of the repeat expansion in someone with the full mutation was generated by scientists in 2012 using SMRT sequencing.

A 2013 review stated that life expectancy for FXS was 12 years lower than the general population and that the causes of death were similar to those found for the general population.

X-linked intellectual disability (previously known as X-linked mental retardation) refers to forms of intellectual disability which are specifically associated with X-linked recessive inheritance.

As with most X-linked disorders, males are more heavily affected than females. Females with one affected X chromosome and one normal X chromosome tend to have milder symptoms.

Unlike many other types of intellectual disability, the genetics of these conditions are relatively well understood. It has been estimated there are ~200 genes involved in this syndrome; of these ~100 have been identified.

X-linked intellectual disability accounts for ~16% of all cases of intellectual disability in males.

Nutrition disorders and nutritional deficits may cause neurodevelopmental disorders, such as spina bifida, and the rarely occurring anencephaly, both of which are neural tube defects with malformation and dysfunction of the nervous system and its supporting structures, leading to serious physical disability and emotional sequelae. The most common nutritional cause of neural tube defects is folic acid deficiency in the mother, a B vitamin usually found in fruits, vegetables, whole grains, and milk products. (Neural tube defects are also caused by medications and other environmental causes, many of which interfere with folate metabolism, thus they are considered to have multifactorial causes.) Another deficiency, iodine deficiency, produces a spectrum of neurodevelopmental disorders ranging from mild emotional disturbance to severe mental retardation. (see also cretinism)

Excesses in both maternal and infant diets may cause disorders as well, with foods or food supplements proving toxic in large amounts. For instance in 1973 K.L. Jones and D.W. Smith of the University of Washington Medical School in Seattle found a pattern of "craniofacial, limb, and cardiovascular defects associated with prenatal onset growth deficiency and developmental delay" in children of alcoholic mothers, now called fetal alcohol syndrome, It has significant symptom overlap with several other entirely unrelated neurodevelopmental disorders. It has been discovered that iron supplementation in baby formula can be linked to lowered I.Q. and other neurodevelopmental delays.

Neurodevelopmental disorders are in their multitude associated with widely varying degrees of difficulty, depending on which there are different degrees of mental, emotional, physical, and economic consequences for individuals, and in turn families, groups and society.

Mental retardation and microcephaly with pontine and cerebellar hypoplasia (MICPCH), also known as Mental retardation, X-linked, syndromic, Najm type (MRXSNA), is a rare genetic disorder of infants characterised by intellectual disability and pontocerebellar hypoplasia.

The disorder is associated with a mutation in the "CASK" gene which is transmitted in an X-linked manner. As with the vast majority of genetic disorders, there is no known cure to MICPCH.

The following values seem to be aberrant in children with CASK gene defects: lactate, pyruvate, 2-ketoglutarate, adipic acid and suberic acid, which seems to backup the proposal that CASK affects mitochondrial function. It is also speculated that phosphoinositide 3-kinase in the inositol metabolism is impacted in the disease, causing folic acid metabolization problems.

Several X-linked syndromes include intellectual disability as part of the presentation. These include:

- Coffin–Lowry syndrome

- MASA syndrome

- MECP2 duplication syndrome

- X-linked alpha thalassemia mental retardation syndrome

- mental retardation and microcephaly with pontine and cerebellar hypoplasia

The prognosis of this condition in childhood usually has a stable outcome, whereas in neonatal is almost always fatal, according to Jurecka, et al.

There is no known cure for Ehlers–Danlos syndrome. Treatment is palliative. Close monitoring of the cardiovascular system, physiotherapy, occupational therapy, and orthopedic instruments (e.g., wheelchairs, bracing, casting) may be helpful. This can help with stabilizing the joints and prevent injury. Orthopedic instruments are helpful for the prevention of further joint damage, especially for long distances, although it is advised that individuals not become entirely dependent on them until there are no other options for mobility. One should avoid activities that cause the joint to lock or overextend.

A physician may prescribe casting to stabilize joints. Physicians may refer a patient to an orthotist for orthotic treatment (bracing). Physicians may also consult a physical and/or occupational therapist to help strengthen muscles and to teach people how to properly use and preserve their joints.

There are different types of physiotherapy. Aquatic therapy promotes muscular development and coordination. With manual therapy, the joint will be gently mobilized within the range of motion and/or manipulations.

If conservative therapy is not helpful, surgical repair of joints may be necessary. Medication to decrease pain or manage cardiac, digestive, or other related conditions may be prescribed. To decrease bruising and improve wound healing, some patients have responded to ascorbic acid (vitamin C). Special precautions are often taken by medical care workers because of the sheer amount of complications that tend to arise in EDS patients. In Vascular EDS, signs of chest or abdominal pain are to be considered trauma situations.

In general, medical intervention is limited to symptomatic therapy. Before pregnancy, patients with EDS should have genetic counseling and familiarize themselves with the risks to their own bodies that pregnancy poses. Children with EDS should be provided with information about the disorder so they can understand why contact sports and other physically stressful activities should be avoided. Children should be taught early on that demonstrating the unusual positions they can maintain due to loose joints should not be done as this may cause early degeneration of the joints. Patients may find it hard to cope with the drawbacks of the disease. In this case, emotional support and behavioral and psychological therapy can be useful. Support groups can be immensely helpful for patients dealing with major lifestyle changes and poor health. Family members, teachers, and friends should be informed about EDS so they can accept and assist the child.

There are no life-threatening complications after the perinatal period (around the time of birth) and the skin conditions persist but to a lesser degree of severity. Individuals have a favourable prognosis as symptoms can be managed and past the infancy stage are not life-threatening. The red skin edema improves after a three-week period but the ichthyosis scaling persists. Asthma has been recorded in some cases later on in the individual's life and sign of atopic dermatitis persist, follicular hyperkeratosis and small amounts of scaling at the scalp that goes on into adulthood but otherwise the individual continues a healthy life.

The progression of symptoms varies widely between each case of FXTAS; the onset of symptoms may be gradual, with progression of the disease spanning multiple years or decades. Alternatively, symptoms may progress rapidly.

FXTAS has shown strong age-dependent penetrance, afflicting older permutation carriers with greater prevalence. Male carriers, age 50 and above have a 30% chance of acquiring FXTAS, while male carriers, age 75 and above, have a 75% chance of developing FXTAS. While initially described to affect male carriers, female carriers of the FMR1 gene mutation have also been found to develop FXTAS. However, due to X-inactivation, female carriers are much less likely to develop classic ataxia and tremor signs for FXTAS, instead demonstrating symptoms such as fibromyalgia, thyroid disease, hypertension, and seizures.

The instability of joints, leading to (sub)luxations and joint pain, often require surgical intervention in patients with Ehlers–Danlos syndrome. Instability of almost all joints can happen but appear most often in the lower and upper extremities, with the wrist, fingers, shoulder, knee, hip, and ankle being most common.

Common surgical procedures are joint debridement, tendon replacements, capsulorraphy, and arthroplasty. Studies have shown that after surgery, degree of stabilization, pain reduction, and patient satisfaction can improve, but surgery does not guarantee an optimal result: Patients and surgeons report being dissatisfied with the results. Consensus is that conservative treatment is more effective than surgery, particularly since patients have extra risks of surgical complications due to the disease. Three basic surgical problems arise due to EDS: the strength of the tissues is decreased, which makes the tissue less suitable for surgery; the fragility of the blood vessels can cause problems during surgery; and wound healing is often delayed or incomplete. If considering surgical intervention, it would be prudent to seek care from a surgeon with extensive knowledge and experience in treating patients with EDS and joint hypermobility issues.

Studies have shown that local anesthetics, arterial catheters and central venous catheters cause a higher risk in haematoma formation in patients with Ehlers–Danlos syndrome. Ehlers–Danlos syndrome patients also show a resistance to local anaesthetics. Resistance to Xylocaine and Bupivacaine is not uncommon, and Carbocaine tends to work better in EDS patents. Special recommendations for anesthesia in EDS patients are prepared by orphananesthesia and deal with all aspects of anesthesia for people with EDS. Detailed recommendations for anesthesia and perioperative care of patients with EDS should be used to improve patient safety.

Surgery with Ehlers–Danlos patients requires careful tissue handling and a longer immobilization afterward.

The infant is intubated post delivery to stabilize the respiratory problems experienced. Often the skin condition becomes less severe resolving itself to flaky dry skin as the individual grows. No intervention is usually required and the condition becomes less severe as the patient grows. The dry skin symptoms can be managed with topical ointments or creams and the individual remains otherwise healthy.

The medical management of FXTAS aims to reduce the level of disability and minimize symptoms. Presently, there are many gaps in the research on the management of FXTAS, as the disorder was first described in the literature in 2001. There is no treatment modality aimed at reversing the pathogenesis of FXTAS. However, there are a variety of drug therapies that are being utilized in the management of FXTAS symptoms, although there is a lack of randomized control trials assessing the efficacy these therapies and support is limited to anecdotal evidence. Therefore, many of the treatments are based on what has been helpful in disorders with similar clinical presentations.

There is no cure for FXTAS. Current treatment includes medications for alleviating symptoms of tremor, ataxia, mood changes, anxiety, cognitive decline, dementia, neuropathic pain, or fibromyalgia. Neurological rehabilitation has not been studied for patients with FXTAS but should also be considered as a possible form of therapy. Additionally, occupational and physical therapy may help to improve performance of functional tasks.

There is currently no specific treatment available for either of these so-called progeroid syndromes. With this in mind, what is most important when making a differential diagnosis with them is based on the prognosis, which appears to be far better in acrogeria.

Treatment of adenylosuccinate lyase deficiency can be done via epilepsy management with anticonvulsive drugs.Additionally the following options include:

- D-ribose and uridine administration

- Ketogenic diet

- S-adenosyl-l-methionine

As of June 2014 (the latest update on HFM in GeneReviews) a total of 32 families had been reported with a clinical diagnosis of HFM of which there was genotypic confirmation in 24 families. Since then, another two confirmed cases have been reported and an additional case was reported based on a clinical diagnosis alone. Most cases emerge from consanguineous parents with homozygous mutations. There are three instances of HFM from non-consanguineous parents in which there were heterozygous mutations. HFM cases are worldwide with mostly private mutations. However, a number of families of Puerto Rican ancestry have been reported with a common pathogenic variant at a splice receptor site resulting in the deletion of exon 3 and the absence of transport function. A subsequent population-based study of newborn infants in Puerto Rico identified the presence of the same variant on the island. Most of the pathogenic variants result in a complete loss of the PCFT protein or point mutations that result in the complete loss of function. However, residual function can be detected with some of the point mutants.

Acrogeria is extremely rare, with only about 40 cases having been reported in the medical literature, since 1941.

Because HFM is a rare disorder, there are no studies that define its optimal treatment. Correction of the systemic folate deficiency, with the normalization of folate blood levels, is easily achieved with high doses of oral folates or much smaller doses of parenteral folate. This will rapidly correct the anemia, immune deficiency and GI signs. The challenge is to achieve adequate treatment of the neurological component of HFM. It is essential that the folate dose is sufficiently high to achieve CSF folate levels as close as possible to the normal range for the age of the child. This requires close monitoring of the CSF folate level. The physiological folate is 5-methyltetrahydrofolate but the oral formulation available is insufficient for treatment of this disorder and a parenteral form is not available. The optimal folate at this time is 5-formyltetrahydrofolate which, after administration, is converted to 5-methyltetrahydrofolate. The racemic mixture of 5-formyltetrahydrofolate (leucovorin) is generally available; the active S-isomer, levoleucovorin, may be obtained as well. Parenteral administration is the optimal treatment if that is possible. Folic acid should not be used for the treatment of HFM. Folic acid is not a physiological folate. It binds tightly to, and may impede, FRα-mediated endocytosis which plays an important role in the transport of folates across the choroid plexus into the CSF (see above). For a further consideration of treatment see GeneReviews.

Animal studies have shown that administration of the drugs vinblastine, streptonigrin, triparano, sulfonamide, tetracycline, antihistamines, and antitumor agents to pregnant mothers have resulted in offspring born with iniencephaly. The drug clomiphene, a drug commonly used for ovulation stimulation in fertility treatments, has also been seen to be associated with iniencephaly.

Studies suggest that prenatal care for mothers during their pregnancies can prevent congenital amputation. Knowing environmental and genetic risks is also important. Heavy exposure to chemicals, smoking, alcohol, poor diet, or engaging in any other teratogenic activities while pregnant can increase the risk of having a child born with a congenital amputation. Folic acid is a multivitamin that has been found to reduce birth defects.

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.

Whether MTHFR deficiency has any effect at all on all-cause mortality is unclear. One Dutch study showed that the MTHFR mutation was more prevalent in younger individuals (36% relative to 30%), and found that elderly men with MTHFR had an elevated mortality rate, attributable to cancer. Among women, however, no difference in life expectancy was seen. More recently, however, a meta-analysis has shown that overall cancer rates are barely increased with an odds ratio of 1.07, which suggests that an impact on mortality from cancer is small or zero.

It is a organophosphate insecticide which acts on the nervous system of insects by inhibiting acetylcholinesterase but are moderately toxic to humans. But it is known have developmental effects appear in fetuses and children even at very small doses. It has been shown to cause abnormal reflexes in neonates, poorer mental development in 2 and 3 year olds, poorer verbal IQ in 3 ½ and 5 year old and pervasive developmental disorder in 2, 3 and 3 ½ year olds.

Standard of care for treatment of CPT II deficiency commonly involves limitations on prolonged strenuous activity and the following dietary stipulations:

- The medium-chain fatty acid triheptanoin appears to be an effective therapy for adult-onset CPT II deficiency.

- Restriction of lipid intake

- Avoidance of fasting situations

- Dietary modifications including replacement of long-chain with medium-chain triglycerides supplemented with L-carnitine