Roberts syndrome is an extremely rare condition that only affects about 150 reported individuals. Although there have been only about 150 reported cases, the affected group is quite diverse and spread worldwide. Parental consanguinity (parents are closely related) is common with this genetic disorder. The frequency of Roberts syndrome carriers is unknown.

Berdon syndrome, also called Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIH syndrome), is an autosomal recessive fatal genetic disorder affecting newborns. In a 2011 study of 227 children with the syndrome, "the oldest survivor [was] 24 years old." The Ann Arbor News reported a five year old survivor at the end of 2015.

It is more prevalent in females, 7 females to 3 males, and is characterized by constipation and urinary retention, microcolon, giant bladder (megacystis), intestinal hypoperistalis, hydronephrosis, and dilated small bowel. The pathological findings consist of an abundance of ganglion cells in both dilated and narrow areas of the intestine. It is a familial disturbance of unknown cause.

Walter Berdon "et al." in 1976 first described the condition in five female infants, two of whom were sisters. All had marked dilatation of the bladder and some had hydronephrosis and the external appearance of prune belly. The infants also had microcolon and dilated small intestines.

Respiratory complications are often cause of death in early infancy.

Marshall–Smith syndrome is not to be confused with:

- Marshall syndrome (aka.Periodic fever, aphthous stomatitis, pharyngitis and adenitis (PFAPA syndrome, see also: Periodic fever syndrome)

- Sotos (like) syndrome

- Weaver-Smith syndrome (WSS)

The incidence of Fraser syndrome is 0.043 per 10,000 live born infants and 1.1 in 10,000 stillbirths, making it a rare syndrome.

Berdon syndrome is autosomal recessive, which means the defective gene is located on an autosome, and two copies of the gene - one inherited from each parent - are required to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene, but are usually not affected by the disorder.

Several genes are known to be implicated in this syndrome: these include ACTG2, LMOD1, MYH11 and MYLK.

Nevo Syndrome is considered to be a rare disorder. Since its first appearance in 1974, only a handful of cases have been reported. Studies have shown showing similarities between Nevo Syndrome with Ehlers-Danlos syndrome as well as Sotos syndrome. There is an astounding overlap of phenotypic manifestations between Nevo Syndrome and the more frequent Sotos syndrome, which are both caused by the NSD1 deletion. Sotos syndrome is an autosomal dominant condition associated with learning disabilities, a distinctive facial appearance, and overgrowth. Studies have shown an overwhelming occurrence (half of those involved in the study) of Nevo syndrome in those individuals of Middle-Eastern descent.

There is no specific treatment or cure for individuals affected with this type of syndrome, though some of the abnormal physical features may be surgically correctable.

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.

Some people may have some mental slowness, but children with this condition often have good social skills. Some males may have problems with fertility.

The prognosis for patients diagnosed with Timothy syndrome is very poor. Of 17 children analyzed in one study, 10 died at an average age of 2.5 years. Of those that did survive, 3 were diagnosed with autism, one with an autism spectrum disorder, and the last had severe delays in language development. One patient with atypical Timothy syndrome was largely normal with the exception of heart arrhythmia. Likewise, the mother of two Timothy syndrome patients also carried the mutation but lacked any obvious phenotype. In both of these cases, however, the lack of severity of the disorder was due to mosaicism.

Low-set ears are ears with depressed positioning of the pinna two or more standard deviations below the population average.

It can be associated with conditions such as:

- Down's syndrome

- Turner Syndrome

- Noonan syndrome

- Patau syndrome

- DiGeorge syndrome

- Cri du chat syndrome

- Edwards syndrome

- Fragile X syndrome

It is usually bilateral, but can be unilateral in Goldenhar syndrome.

3C syndrome is very rare, occurring in less than 1 birth per million. Because of consanguinity due to a founder effect, it is much more common in a remote First Nations village in Manitoba, where 1 in 9 people carries the recessive gene.

Overall, the estimated prevalence of Stickler syndrome is about 1 in 10,000 people. Stickler syndrome affects 1 in 7,500 to 9,000 newborns.

As the syndrome is due to a chromosomal non-disjunction event, the recurrence risk is not high compared to the general population. There has been no evidence found that indicates non-disjunction occurs more often in a particular family.

Pashayan syndrome also known as Pashayan–Prozansky Syndrome, and blepharo-naso-facial syndrome is a rare syndrome. Facial abnormalities characterise this syndrome as well as malformation of extremities. Specific characteristics would be a bulky, flattened nose, where the face has a mask like appearance and the ears are also malformed.

A subset of Pashayan syndrome has also been described, known as "cerebrofacioarticular syndrome", "Van Maldergem syndrome'" or "Van Maldergem–Wetzburger–Verloes syndrome". Similar symptoms are noted in these cases as in Pashayan syndrome.

Fraser syndrome (also known as Meyer-Schwickerath's syndrome, Fraser-François syndrome, or Ullrich-Feichtiger syndrome) is an autosomal recessive congenital disorder. Fraser syndrome is named for the geneticist George R. Fraser, who first described the syndrome in 1962.

At this time, there are no other phenotypes (observable expressions of a gene) that have been discovered for mutations in the ESCO2 gene.

Nevo Syndrome is an autosomal recessive disorder. Most times in which a child is afflicted with Nevo Syndrome, both their parents are of average height and weight. It is only until after birth when the characteristic physical traits associated with disease are manifested, and the disorder is actually diagnosed. One study showed that despite the increased growth rates, the patient was completely healthy up until age 6, when he was admitted into the hospital. Nevo syndrome is usually associated with early childhood fatality. Children with Nevo Syndrome have a high occurrence of death due to cardiac arrest because their developing hearts cannot keep up with their overgrown body.

Rosselli–Gulienetti syndrome, also known as Zlotogora–Ogur syndrome and Bowen–Armstrong syndrome, is a type of congenital ectodermal dysplasia syndrome. The syndrome is relatively rare and has only been described in a few cases.

Many professionals that are likely to be involved in the treatment of those with Stickler's syndrome, include anesthesiologists, oral and maxillofacial surgeons; craniofacial surgeons; ear, nose, and throat specialists, ophthalmologists, optometrists, audiologists, speech pathologists, physical therapists and rheumatologists.

Scalp–ear–nipple syndrome (also known as "Finlay–Marks syndrome") is a condition associated with aplasia cutis congenita.

In the United States, sarcoidosis has a prevalence of approximately 10 cases per 100,000 whites and 36 cases per 100,000 blacks. Heerfordt syndrome is present in 4.1–5.6% of those with sarcoidosis.

Mutations in the "TBX5" gene cause Holt–Oram syndrome. The "TBX5" gene plays a role in the development of the heart and upper limbs before birth. In particular, this gene appears to be important for the process that divides the developing heart into four chambers (cardiac septation). The "TBX5" gene also appears to play a critical role in regulating the development of bones in the arm and hand. Mutations in this gene probably disrupt the development of the heart and upper limbs, leading to the characteristic features of Holt–Oram syndrome.

Holt–Oram syndrome is considered an autosomal dominant disorder. This means the defective gene is located on an autosome, and only one copy of the gene, inherited from a parent who has the disorder, is sufficient to cause the disorder.

Other cases of Holt–Oram syndrome are sporadic, and result from new mutations in the TBX5 gene that occur in people with no history of the disorder in their family. Holt–Oram syndrome is estimated to affect 1 in 100,000 individuals.In some cases, Holt-Oram has a multiplier effect when passed on generation to generation. An affected child of an affected parent will likely face greater challenges than the parent did. In rare cases, some carriers are unable to reproduce at all due to the severity of the condition.

Turner syndrome occurs in between one in 2000 and one in 5000 females at birth.

Approximately 99 percent of fetuses with Turner syndrome spontaneously terminate during the first trimester. Turner syndrome accounts for about 10 percent of the total number of spontaneous abortions in the United States.