Say–Neger syndrome is a rare X-linked genetic disorder that is mostly characterized as developmental delay. It is one of the rare causes of short stature. It is closely related with trigonocephaly (a misshapen forehead due to premature fusion of bones in the skull). People with Say–Meyer syndrome have impaired growth, deficits in motor skills development and mental state.

It is suggested that it is from a X-linked transmission.

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.

Encephaloceles occur rarely, at a rate of one per 5,000 live births worldwide. Encephaloceles of the back of the head are more common in Europe and North America, while encephaloceles on the front of the head more frequently occur in Southeast Asia, Africa, Malaysia, and Russia. Ethnic, genetic, and environmental factors, as well as parental age, can all affect the likelihood of encephaloceles. The condition can occur in families with a family history of spina bifida.

The growth retardation dates from the intrauterine period (development in the uterus.) The long-term developmental growth and outcome is not known, but the early childhood development is known, which is said to be moderately delayed. Craniosynostosis is usually rare among the X-Linked Intellectual Disability Syndromes, but when it is present, it affects the metopic structure (forehead).

Brain trauma in the developing human is a common cause (over 400,000 injuries per year in the US alone, without clear information as to how many produce developmental sequellae) of neurodevelopmental syndromes. It may be subdivided into two major categories, congenital injury (including injury resulting from otherwise uncomplicated premature birth) and injury occurring in infancy or childhood. Common causes of congenital injury are asphyxia (obstruction of the trachea), hypoxia (lack of oxygen to the brain) and the mechanical trauma of the birth process itself.

Current research is focusing on clearly defining the phenotype associated with tetrasomy 18p and identifying which genes cause medical and developmental problems when present in four copies.

Microlissencephaly is listed in Orphanet database as a rare disease. There is no much information available about the epidemiology of microlissencepahly in literature. A PhD thesis has estimated the prevalence of microlissencepahly in South–Eastern Hungary between July 1992 and June 2006 to be a case every 91,000 live births (0.11:10,000).

The prognosis is poor; affected individuals are either stillborn or die shortly after birth. The longest survival reported in literature is of 134 days.

This syndrome is transmitted as an autosomal recessive disorder and there is a risk for recurrence of 25% in future pregnancies.

All reported cases of tetrasomy 18p have some degree of intellectual disability. Most individuals score in the moderate range of intellectual disability based on standardized testing.

Adducted thumb syndrome recessive form is a rare disease affecting multiple systems causing malformations of the palate, thumbs, and upper limbs. The name Christian syndrome derives from Joe. C. Christian, the first person to describe the condition. Inheritance is believed to be autosomal recessive, caused by mutation in the CHST14 (carbohydrate sulfotransferase 14) gene.

The mechanism of rhizomelic chondrodysplasia punctata in the case of "type 1" of this condition one finds that peroxisome objective is PEX7, in peroxisome assembly.There are 3 pathways that "count on" PEX7 and are:

Genitopatellar Syndrome is an autosomal dominant inheritance where the mutation in the KAT6B causes the syndrome. The KAT6B gene is responsible for making an enzyme called histone acetyltransferase which functions in regulating and making of histone which are proteins that attach to DNA and give the chromosomes their shape. The function of histone acetyltransferase produced from KAT6B is unknown but it is considered as a regulator of early developments. There is little known about how the mutation in the KAT6B causes the syndrome but researchers suspects that the mutations occur near the end of the KAT6B gene and causes it to produce shortened acetyltransferase enzyme. The shortened enzyme alters the regulation of other genes. On the other hand, the mutation of KAT6B leading to the specific features of genitopatellar syndrome is still not surely proven.

This condition is a consequence of mutations in the PEX7 gene, GNPAT gene (which is located on chromosome 1) and AGPS gene, the condition is acquired in a autosomal recessive manner.

1p36 deletion syndrome (also known as monosomy 1p36) is a congenital genetic disorder characterized by moderate to severe intellectual disability, delayed growth, hypotonia, seizures, limited speech ability, malformations, hearing and vision impairment, and distinct facial features. The symptoms may vary, depending on the exact location of the chromosomal deletion.

The condition is caused by a genetic deletion (loss of a segment of DNA) on the outermost band on the short arm (p) of chromosome 1. It is one of the most common deletion syndromes. It is estimated that the syndrome occurs in one in every 5,000 to 10,000 births. Knowledge of the disorder has increased a great deal over the last decade, mainly because more patients have been accurately diagnosed and described in international medical literature.

Microlissencephaly (MLIS) is a rare congenital brain disorder that combines severe microcephaly (small head) with lissencephaly (smooth brain surface due to absent sulci and gyri). Microlissencephaly is a heterogeneous disorder i.e. it has many different causes and a variable clinical course. Microlissencephaly is a malformation of cortical development (MCD) that occurs due to failure of neuronal migration between the third and fifth month of gestation as well as stem cell population abnormalities. Numerous genes have been found to be associated with microlissencephaly, however, the pathophysiology is still not completely understood.

The combination of lissencephaly with severe congenital microcephaly is designated as microlissencephaly only when the cortex is abnormally thick. If such combination exists with a normal cortical thickness (2.5 to 3 mm), it is known as "microcephaly with simplified gyral pattern" (MSGP). Both MLIS and MSGP have a much more severe clinical course than microcephaly alone. They are inherited in autosomal recessive manner. Prior to 2000, the term “microlissencephaly” was used to designate both MLIS and MSGP.

Although the epidemiologic data indicate that all variants of normal growth are twice as common in boys as in girls, referrals for short stature reflect an even more divergent sex ratio. This likely reflects greater concern about males who are shorter than their peers or who have delayed sexual development.

No racial bias has been identified. Patterns of growth consistent with CDGP occur in infants as young as 3–6 months. However, individuals often do not seek medical attention until puberty, when lack of sexual development becomes a concern and discrepancy in height from peers is magnified by the delay in pubertal growth spurt.

Life expectancy for individuals with hypochondroplasia is normal; the maximum height is about 147 cm or 4.8 ft.

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.

The collecting system is the structure that collects urine directly from the kidney tissue and routes it by way of the ureter to the bladder. Structural renal abnormalities are rare in both sexes.

CDGP is not associated with increased mortality because it is a variant of normal growth rather than a disease. However, in some affected individuals, it can be associated with significant psychological stress, resulting in poor self-image and social withdrawal. In recent years, researchers have also found that individuals with CDGP may be at increased risk for reduced bone mass in adulthood because of the delay in sex steroid influence on bone accrual during adolescence.

Recovery is difficult to predict prior to surgery, and depends on the type of brain tissue involved and location of the encephaloceles. If surgery is successful, and developmental delays have not occurred, a patient can develop normally. Where neurologic and developmental damage has occurred, the specialists will focus on minimizing both mental and physical disabilities.

In general, when the bulging material consists of primarily cerebrospinal fluid, a complete recovery can occur. When a large amount of brain tissue is present in the encephaloceles, there is a higher chance of perioperative complication.

Genitopatellar syndrome is a rare disorder with characteristic craniofacial features, congenital flexion contractures of the lower limbs, absent or abnormal patellae, urogenital anomalies, and severe psychomotor retardation.

In 2012, it was shown that mutations in the gene KAT6B cause the syndrome.

In terms of cause this disorder is transmitted as an autosomal dominant trait affecting the "FGFR3" gene on chromosome 4p16.3, there is currently no cure for this condition.

Nicolaides–Baraitser syndrome (NCBRS) is a rare genetic condition caused by de novo missense mutations in the SMARCA2 gene and has only been reported in less than 100 cases worldwide. NCBRS is a distinct condition and well recognizable once the symptoms have been identified.

Many types of dwarfism are currently impossible to prevent because they are genetically caused. Genetic conditions that cause dwarfism may be identified with genetic testing, by screening for the specific variations that result in the condition. However, due to the number of causes of dwarfism, it may be impossible to determine definitively if a child will be born with dwarfism.

Dwarfism resulting from malnutrition or a hormonal abnormality may be treated with an appropriate diet or hormonal therapy. Growth hormone deficiency may be remedied via injections of human growth hormone (HGH) during early life.