The disorder is thought to be related to mutations in the PDE3A gene.

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.

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 Primrose syndrome is currently unknown. This condition is extremely rare and seems to spontaneously occur, regardless of family history.

In the case studied by Dalai et al. in 2010, it was found that an abnormally high amount of calcitonin, a hormone secreted by the thyroid gland to stabilize blood calcium levels, was present in the blood serum. This suggests that the thyroid gland is releasing an abnormal amount of calcitonin, resulting in the disruption of calcium level homeostasis. No molecular cause was found, but an expanded microarray analysis of the patient found a 225.5 kb deletion on chromosome 11p between rs12275693 and rs1442927. Whether or not this deletion is related to the syndrome or is a harmless mutation is unknown. The deletion was not present in the patient's mother's DNA sample, but the father's DNA was unavailable.

Hypertension and brachydactyly syndrome (HTNB) also known as Bilginturan syndrome and brachydactyly type E among others is a very rare genetic disorder.

It was first reported in 1973 by N. Bilginturan et al. The estimated prevalence is less than 1 out of 1,000,000.

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 syndrome appears to be inherited in an autosomal dominant fashion.

Molecular analyses suggest that the causative mutations cause a truncation of the protein. These mutations result in the loss of PEST sequence in the protein. This loss is associated with a prolonged half life of the protein.

Mutations in Notch 3 were found to be associated with this syndrome.

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.

Shprintzen–Goldberg syndrome is a multiple anomaly syndrome that has craniosynostosis, multiple abdominal hernias, cognitive impairment, and other skeletal malformations as key features. Several reports have linked the syndrome to a mutation in the "FBN1" gene, but these cases do not resemble those initially described in the medical literature in 1982 by Shprintzen and Goldberg, and Greally et al. in 1998 failed to find a causal link to FBN1. At this time, the cause of Shprintzen–Goldberg syndrome remains uncertain. The syndrome is rare with fewer than 50 cases described in the medical literature to date.

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.

Urban–Rogers–Meyer syndrome, also known as Prader–Willi habitus, osteopenia, and camptodactyly or Urban syndrome, is an extremely rare inherited congenital disorder first described by Urban et al. (1979). It is characterized by genital anomalies, mental retardation, obesity, contractures of fingers, and osteoporosis, though further complications are known.

Spondylo-ocular syndrome is a rare genetic disorder characterised by lesions in the eye and the spine.

The lateral meningocele syndrome is a very rare skeletal disorder with facial anomalies, hypotonia and meningocele-related neurologic dysfunction.

This syndrome is caused by inactivating mutations in the xylosyltransferase (XYLT2) gene. It is inherited in an autosomal recessive manner.

Kosaki overgrowth syndrome (KOGS) is a rare (27 cases reported by 2017) syndrome caused by mutations in the PDGFRB gene.

The common symptoms in all reported cases of primrose syndrome include ossified pinnae, learning disabilities or mental retardation, hearing problems, movement disorders (ataxia, paralysis, and parkinsonism among others (likely due, in part, to calcification of the basal ganglia), a torus palatinus (a neoplasm on the mouth's hard palate), muscle atrophy, and distorted facial features. Other symptoms usually occur, different in each case, but it is unknown whether or not these symptoms are caused by the same disease.

Raine syndrome (RNS), also called osteosclerotic bone dysplasia, is a rare autosomal recessive congenital disorder characterized by craniofacial anomalies including microcephaly, noticeably low set ears, osteosclerosis, a cleft palate, gum hyperplasia, a hypoplastic nose, and eye proptosis. It is considered to be a lethal disease, and usually leads to death within a few hours of birth. However, a recent report describes two studies in which children with Raine Syndrome have lived to 8 and 11 years old, so it is currently proposed that there is a milder expression that the phenotype can take (Simpson 2009).

It was first characterized in 1989 in a report that was published on an infant that had been born with an unknown syndrome, that later came to be called Raine Syndrome.

The current research describes Raine Syndrome as a neonatal osteosclerotic bone dysplasia, indicated by its osteosclerotic symptoms that are seen in those suffering from the disease. It has been found that a mutation in the gene FAM20C is the cause of the Raine Syndrome phenotype. This microdeletion mutation leads to an unusual chromosome 7 arrangement. The milder phenotypes of Raine Syndrome, such as those described in Simpson’s 2007 report, suggest that Raine Syndrome resulting from missense mutations may not be as lethal as the other described mutations (OMIM). This is supported by findings from Fradin et al. (2011), who reported on children with missense mutations to FAM20C and lived to ages 1 and 4 years, relatively much longer than the life spans of the previously reported children. Simpson et al.’s (2007) report states that to date, effected individuals have had chromosome 7 uniparental isodisomy and a 7p telomeric microdeletion. They had abnormal chromosome 7 arrangements, with microdeletions of their D7S2477 and D7S1484 markers (Simpson 2007).

Raine Syndrome appears to be an autosomal recessive disease. There are reports of recurrence in children born of the same parents, and an increased occurrence in children of closely related, genetically similar parents. Individuals with Raine Syndrome were either homozygous or compound heterozygous for the mutation of FAM20C. Also observed have been nonsynonomous mutation and splice-site changes (Simpson et al. 2007).

FAM20C, located on chromosome 7p22.3, is an important molecule in bone development. Studies in mice have demonstrated its importance in the mineralization of bones in teeth in early development (OMIM, Simpson et al. 2007, Wang et al. 2010). FAM20C stands for “family with sequence similarity 20, member C.” It is also commonly referred to as DMP-4. It is a Golgi-enriched fraction casein kinase and an extracellular serine/threonine protein kinase. It is 107,743 bases long, with 10 exons and 584 amino acids (Weizmann Institute of Science).

Malpuech facial clefting syndrome, also called Malpuech syndrome or Gypsy type facial clefting syndrome, is a rare congenital syndrome. It is characterized by facial clefting (any type of cleft in the bones and tissues of the face, including a cleft lip and palate), a appendage (a "human tail"), growth deficiency, intellectual and developmental disability, and abnormalities of the renal system (kidneys) and the male genitalia. Abnormalities of the heart, and other skeletal malformations may also be present. The syndrome was initially described by Guilliaume Malpuech and associates in 1983. It is thought to be genetically related to Juberg-Hayward syndrome. Malpuech syndrome has also been considered as part of a spectrum of congenital genetic disorders associated with similar facial, urogenital and skeletal anomalies. Termed "3MC syndrome", this proposed spectrum includes Malpuech, Michels and Mingarelli-Carnevale (OSA) syndromes. Mutations in the "COLLEC11" and "MASP1" genes are believed to be a cause of these syndromes. The incidence of Malpuech syndrome is unknown. The pattern of inheritance is autosomal recessive, which means a defective (mutated) gene associated with the syndrome is located on an autosome, and the syndrome occurs when two copies of this defective gene are inherited.

Smith Martin Dodd syndrome is a very rare genetic disorder first described by Smith et al. in 1994. It is characterized by small eyes, a diaphragmatic hernia, and Tetralogy of Fallot, a congenital heart defect. The only known case is of a 9-year-old boy with several congenital anomalies including a diaphragmatic hernia, microphthalmia, and Tetralogy of Fallot. It was found that the boy had a reciprocal translocation t(1;15)(q41;q21.2). A congenital diaphragmatic hernia is consistent with chromosome 1q41-q42 deletion syndrome, and the report by Smith et al. suggested that genes involved in the translocation may be important for the development of morphological characteristics, especially those of the eye or heart.

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.

Stimmler syndrome is a rare autosomal recessive congenital disorder first described by Stimmler et al. in 1970. It is characterized by dwarfism, diabetes, a small head, and high levels of alanine in the urine.

Acrocallosal syndrome (also known as ACLS) is a rare autosomal recessive syndrome characterized by corpus callosum agenesis, polydactyly, multiple dysmorphic features, motor and mental retardation, and other symptoms. The syndrome was first described by Albert Schinzel in 1979.

It is associated with "GLI3".

The true prevalence of PMS has not been determined. More than 1200 people have been identified worldwide according the Phelan-McDermid Syndrome Foundation. However, it is believed to be underdiagnosed due to inadequate genetic testing and lack of specific clinical features. It is known to occur with equal frequency in males and females. Studies using chromosomal microarray for diagnosis indicate that at least 0.5% of cases of ASD can be explained by mutations or deletions in the "SHANK3" gene. In addition when ASD is associated with ID, "SHANK3" mutations or deletions have been found in up to 2% of individuals.

In a newborn boy thought to have Fryns syndrome, Clark and Fenner-Gonzales (1989) found mosaicism for a tandem duplication of 1q24-q31.2. They suggested that the gene for this disorder is located in that region. However, de Jong et al. (1989), Krassikoff and Sekhon (1990), and Dean et al. (1991) found possible Fryns syndrome associated with anomalies of chromosome 15, chromosome 6, chromosome 8(human)and chromosome 22, respectively. Thus, these cases may all represent mimics of the mendelian syndrome and have no significance as to the location of the gene for the recessive disorder.

By array CGH, Slavotinek et al. (2005) screened patients with DIH and additional phenotypic anomalies consistent with Fryns syndrome for cryptic chromosomal aberrations. They identified submicroscopic chromosome deletions in 3 probands who had previously been diagnosed with Fryns syndrome and had normal karyotyping with G-banded chromosome analysis. Two female infants were found to have microdeletions involving 15q26.2 (see 142340), and 1 male infant had a deletion in band 8p23.1 (see 222400).

Yim–Ebbin syndrome is a congenital disorder characterized by the absence of arms, a cleft lip and palate, hydrocephalus, and an iris coloboma. It was first described by Yim and Ebbin in 1982, and later by Thomas and Donnai in 1994. In 1996, a third case was reported by Froster et al. who suggested that the three cases were related and represented a distinct syndrome. In 2000, a similar case was reported by Pierri et al.

It is also known as "amelia cleft lip palate hydrocephalus iris coloboma".