Children with Pfeiffer syndrome types 2 and 3 "have a higher risk for neurodevelopmental disorders and a reduced life expectancy" than children with Pfeiffer syndrome type 1, but if treated, favorable outcomes are possible. In severe cases, respiratory and neurological complications often lead to early death.

Currently there are only around 26 people in the world that are known to have this rare condition. Inheritance is thought to be X-linked recessive.

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.

The key problem is the early fusion of the skull, which can be corrected by a series of surgical procedures, often within the first three months after birth. Later surgeries are necessary to correct respiratory and facial deformities.

The prognosis varies widely from case to case, depending on the severity of the symptoms. However, almost all people reported with Aicardi syndrome to date have experienced developmental delay of a significant degree, typically resulting in mild to moderate to profound intellectual disability. The age range of the individuals reported with Aicardi syndrome is from birth to the mid 40s.

There is no cure for this syndrome.

Worldwide prevalence of Aicardi Syndrome is estimated at several thousand, with approximately 900 cases reported in the United States.

Acrocephalosyndactylia (or acrocephalosyndactyly) is the common presentation of craniosynostosis and syndactyly.

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.

Catel–Manzke syndrome is a rare genetic disorder characterized by distinctive abnormalities of the index fingers; the classic features of Pierre Robin syndrome; occasionally with additional physical findings. "Pierre Robin syndrome" refers to a sequence of abnormalities that may occur as a distinct syndrome or as part of another underlying disorder. Pierre Robin syndrome is characterized by an unusually small jaw (micrognathia), downward displacement or retraction of the tongue (glossoptosis), and incomplete closure of the roof of the mouth (cleft palate). It is also linked to hyper mobility syndrome.

It has several different types:

- type 1 - Apert syndrome

- type 2 - Crouzon syndrome

- type 3 - Saethre-Chotzen syndrome

- type 5 - Pfeiffer syndrome

A related term, "acrocephalopolysyndactyly" (ACPS), refers to the inclusion of polydactyly to the presentation. It also has multiple types:

- type 1 - Noack syndrome; now classified with Pfeiffer syndrome

- type 2 - Carpenter syndrome

- type 3 - Sakati-Nyhan-Tisdale syndrome

- type 4 - Goodman syndrome; now classified with Carpenter syndrome

- type 5 - Pfeiffer syndrome

It has been suggested that the distinction between "acrocephalosyndactyly" versus "acrocephalopolysyndactyly" should be abandoned.

By 1990, 65 patients had been reported in the literature, with no sex or ethnic preference notable. Some individuals present with minimal malformation; rarely patients have died during infancy as a result of severe central nervous system involvement or respiratory complications. Several syndromes are related to the Freeman–Sheldon syndrome spectrum, but more information is required before undertaking such nosological delineation.

Schimmelpenning syndrome appears to be sporadic rather than inherited, in almost all cases. It is thought to result from genetic mosaicism, possibly an autosomal dominant mutation arising after conception and present only in a subpopulation of cells. The earlier in embryological development such a mutation occurs, the more extensive the nevi are likely to be and the greater the likelihood of other organ system involvement.

There are little data on prognosis. Rarely, some patients have died in infancy from respiratory failure; otherwise, life expectancy is considered to be normal.

The cause of this condition is unknown but evidence of familial inheritance and sporadic genetic mutation has been linked to cases of FHS. Two possibly familial cases have been reported—one in a mother and son, and the other in a mother and daughter. This suggests an autosomal dominant inheritance but additional cases need to be investigated to establish this. Another report has suggested that the inheritance may be autosomal recessive. In all of these cases, however, the mothers and children were not similarly affected, suggesting a variable clinical expression of the syndrome.

In a study published by the "American Journal of Human Genetics" in 2012, exome sequencing was used to investigate a group of unrelated individuals with classic features of FHS and identified heterozygous mutations in SRCAP as causative of this disorder. Each reported mutation was truncating (nonsense or frameshift) and occurred between codons 2,407 and 2,517 in exon 34, resulting in the loss of three C-terminal AT-hook motifs. SRCAP encodes a SNF2-related chromatin-remodeling ATPase that is a coactivator for CREB-binding protein (or CBP), which is the major cause of Rubinstein–Taybi syndrome. This disrupted interaction between the proteins most likely explains the clinical overlap between FHS and RTS.

- SRCAP has been shown to transduce signals of nuclear (steroid) hormone receptors and Notch pathways, showing that it plays diverse roles in gene expression.

- SRCAP contains several functional domains (SNF2 like ATPase, an N-terminal HSA domain, and three C-terminal AT-hook DNA-binding motifs).

- The CBP interaction domain of SRCAP is located centrally.

Thus, the mechanism of disease in FHS is suspected to be dominant-negative (or antimorphic) due to the mutation in the final exon that results in the loss of the major transactivation function of SRCAP (or loss of one or more critical domains). All of the patients that carried the mutation also had obvious physical symptoms (i.e., prominent nose, delayed bone age, and short stature). Those who tested negative for the mutation often had dysmorphic facial features distinct from classical FHS, as well as a formal diagnosis of autism.

Schimmelpenning syndrome is a neurocutaneous condition characterized by one or more sebaceous nevi, usually appearing on the face or scalp, associated with anomalies of the central nervous system, ocular system, skeletal system, cardiovascular system, and genitourinary system.

Synonyms include: "Linear nevus sebaceous syndrome (LNSS)", "Schimmelpenning-Feuerstein-Mims syndrome", "Feuerstein-Mims syndrome", "sebaceous nevus syndrome", "Solomon syndrome", and "Jadassohn's nevus phakomatosis". "Nevus" is sometimes spelled "naevus" and "sebaceous" may also be spelled "sebaceus". "Epidermal nevus syndrome" is sometimes used as a synonym, but more often as a broader term referring to Schimmelpenning syndrome in addition to nevus comedonicus syndrome, CHILD syndrome, Becker's nevus syndrome, and phakomatosis pigmentokeratotica.

The classic Schimmelpenning syndrome diagnosis comprises a triad of sebaceous nevi, seizures, and mental retardation. The condition was first reported by Gustav Schimmelpenning in 1957 and independently reported by Feuerstein and Mims in 1962.

There are no cures for FHS. Close monitoring of growth in the first few years is essential, as well as annual general health screening and tests listed below. An FHS diagnosis will affect the individual and those there to support them.

Managing symptoms and features of FHS involves maintaining a close watch on the patient's physical as well as mental health. This would include:

- Sequencing of SRCAP exons 31–34 in all suspected cases

- Complete assessments of auditory and visual systems

- Renal and urinary tract ultrasound

- Orthopedic assessment of hip dysplasia and clavicle abnormalities

- Neurologic assessment if there is a suspicion of seizures

- Dental hygiene to prevent cavities and to monitor for malocclusion

- Evaluation for growth hormone deficiency at baseline, to be repeated if loss of growth velocity occurs

- Monitoring of bone age and pubertal timing in case of precocious puberty

- Psychoeducational assessments corrected for deficiencies in expressive language and sensory issues

- Monitoring of behavioral disturbances and provision of early intervention

- Counseling for families regarding recurrence risk and the offspring of individuals with FHS

Special education programs and vocational training to address developmental disabilities are highly recommended, as well as communication rehabilitation with sign language or alternative means of communication. Behavior management strategies could also include referrals to behavior specialists or psychologists for help. For those concerned, genetic counseling can be sought for issues related to testing of at-risk relatives.

Omphalocele has been described in two patients with Apert syndrome by Herman T.E. et al. (USA, 2010) and by Ercoli G. et al. (Argentina, 2014). An omphalocele is a birth defect in which an intestine or other abdominal organs are outside of the body of an infant because of a hole in the bellybutton area. However, the association between omphalocele and Apert syndrome is not confirmed yet, so additional studies are necessary.

The exact cause of the condition is unknown. In some cases, close family members may share this condition. In other cases, no other related persons have this condition. The scientific name for the condition is syndactyly, although this term covers both webbed fingers and webbed toes. Syndactyly occurs when apoptosis or programmed cell death during gestation is absent or incomplete. Webbed toes occur most commonly in the following circumstances:

- Syndactyly or Familial Syndactyly

- Down syndrome

It is also associated with a number of rare conditions, notably:

- Aarskog–Scott syndrome

- Acrocallosal syndrome

- Apert's syndrome

- Bardet-Biedl syndrome

- Carpenter syndrome

- Cornelia de Lange syndrome

- Edwards syndrome

- Jackson–Weiss syndrome

- Fetal hydantoin syndrome

- Miller syndrome

- Pfeiffer syndrome

- Smith-Lemli-Opitz syndrome

- Timothy syndrome

- Ectodermal Dysplasia

- Klippel-Feil Syndrome

Acrocephalosyndactyly may be an autosomal dominant disorder. Males and females are affected equally; however research is yet to determine an exact cause. Nonetheless, almost all cases are sporadic, signifying fresh mutations or environmental insult to the genome. The offspring of a parent with Apert syndrome has a 50% chance of inheriting the condition. In 1995, A.O.M. Wilkie published a paper showing evidence that acrocephalosyndactyly is caused by a defect on the fibroblast growth factor receptor 2 gene, on chromosome 10.

Apert syndrome is an autosomal dominant disorder; approximately two-thirds of the cases are due to a C to G mutation at the position 755 in the FGFR2 gene, which causes a Ser to Trp change in the protein. This is a male-specific mutation hotspot: in a study of 57 cases, the mutation always occurred on the paternally derived allele. On the basis of the observed birth prevalence of the disease (1 in 70,000), the apparent rate of C to G mutations at this site is about .00005, which is 200- to 800-fold higher than the usual rate for mutations at CG dinucleotides. Moreover, the incidence rises sharply with the age of the father. Goriely et al. (2003) analyzed the allelic distribution of mutations in sperm samples from men of different ages and concluded that the simplest explanation for the data is that the C to G mutation gives the cell an advantage in the male germline.

It is still not very clear why people with Apert Syndrome have both craniosynostosis and syndactyly. There has been one study that suggests it has something to do with the expression of three isoforms of FGFR2, the gene with the point mutations that causes the syndrome in 98% of the patients.

KGFR, keratinocyte growth factor receptor, is an isoform active in the metaphysis and interphalangeal joints. FGFR1 is an isoform active in the diaphysis. FGFR2-Bek is active in the metaphysis, as well as the diaphysis, but also in the interdigital mesenchyme. The point mutation increases the ligand-dependent activation of FGFR2, and thus of its isoforms. This means that FGFR2 loses its specificity, causing binding of FGFs that normally do not bind to the receptor. Since FGF suppresses apoptosis, the interdigital mesenchyme is maintained. FGF also increases replication and differentiation of osteoblasts, thus early fusion of several sutures of the skull. This may explain why both symptoms are always found in Apert Syndrome.

Studies of the life expectancy of patients with Alport syndrome are rare, but one 2012 study of 456 male patients from across Europe who received a kidney transplant found that they had somewhat increased life expectancy compared to matched controls (the controls were "randomly selected from the same age, year, and modality categories").

Very few risk factors for choanal atresia have been identified. While causes are unknown, both genetic and environmental triggers are suspected. One study suggests that chemicals that act as endocrine disrupters may put an unborn infant at risk. A 2012 epidemiological study looked at atrazine, a commonly used herbicide in the U.S., and found that women who lived in counties in Texas with the highest levels of this chemical being used to treat agricultural crops were 80 times more likely to give birth to infants with choanal atresia or stenosis compared to women who lived in the counties with the lowest levels. Another epidemiological report in 2010 found even higher associations between increased incidents of choanal atresia and exposure to second-hand-smoke, coffee consumption, high maternal zinc and B-12 intake and exposure to anti-infective urinary tract medications.

Webbed toes in humans are a purely cosmetic condition. This condition does not impair the ability to perform any activity, including walking, running, or swimming. Depending on the severity and structure of the webbing, there can be some minor consequences.

People with more severe webbed toes may have a slight disadvantage for activities that benefit from prehensile toes, due to the toes being unable to split or move laterally. Although not scientifically proven, some believe that this condition can possibly allow for a slight advantage, specifically, in athletics. Considering your big toe is a main source for balance, having your second and third toe webbed could virtually be seen as having two big toes. Thus, allowing for better balance in athletics such as running or dance.

Psychological stress may arise from the fear of negative reactions to this condition from people who do not have webbed toes, particularly in severe cases where the nails are stuck visibly close together. Many people with webbed toes can physically feel the toes touching under the fused skin, which can cause psychological discomfort. This is due to the nerves of each toe fully developing and independent muscles working. In other cases where the toes are partially webbed, the webbing holds the separate tips of the toes against one another and prevents the muscles from spreading the toes apart, causing the toes and sometimes nails to press together.

However a disadvantage would be a difficulty in wearing flip-flops or other such footwear in warm countries. People with webbed toes may be unable to wear Toe socks or Vibram FiveFingers shoes. Difficulty navigating rough terrain barefoot, such as rocks at a beach is also common. In some cases the toes grow at different lengths causing the toes to buckle or bend and many people with severe webbed toes experience cramping in these toes due to the muscles and ligaments being strained.

In regard to the epidemiology of multicystic dysplasia kidney, the incidence of MCDK is estimated to be 1 in every 4,000 live births, making it rare in terms of the general population.

Approximately 4% of the general population have an elongated styloid process, and of these about 4% give rise to the symptoms of Eagle syndrome. Therefore, the incidence of stylohyoid syndrome may be about 0.16%.

Patients with this syndrome tend to be between 30 and 50 years of age but it has been recorded in teenagers and in patients > 75 years old. It is more common in women, with a male:female ratio ~ 1:2.

The cause of acrogeria is still not well determined. This disorder is thought to be inherited as an autosomal recessive genetic trait. However, the mode of genetic inheritance is not accurately known. It has been considered autosomal dominant and autosomal recessive, though most reported cases own a positive family background.

Mutations in the COL3A1 gene, located at chromosome 2q31–q32, have been reported in varied phenotypes, including acrogeria and vascular rupture in Ehlers-Danlos' syndrome (more especially type IV).

In the fibroblast culture, a reduction of RNA messenger cells in collagen types I and II was found, as well as reduced life expectancy of the fibroblasts most prematurely showing morphological alterations typical of aging.

This seems perfectly compatible with the patients' aged phenotype.