Opitz G/BBB Syndrome is a rare genetic condition caused by one of two major types of mutations: MID1 mutation on the short (p) arm of the X chromosome or a mutation of the 22q11.2 gene on the 22nd chromosome. Since it is a genetic disease, it is an inherited condition. However, there is an extremely wide variability in how the disease presents itself.

In terms of prevention, several researchers strongly suggest prenatal testing for at-risk pregnancies if a MID1 mutation has been identified in a family member. Doctors can perform a fetal sex test through chromosome analysis and then screen the DNA for any mutations causing the disease. Knowing that a child may be born with Opitz G/BBB syndrome could help physicians prepare for the child’s needs and the family prepare emotionally. Furthermore, genetic counseling for young adults that are affected, are carriers or are at risk of carrying is strongly suggested, as well (Meroni, Opitz G/BBB syndrome, 2012). Current research suggests that the cause is genetic and no known environmental risk factors have been documented. The only education for prevention suggested is genetic testing for at-risk young adults when a mutation is found or suspected in a family member.

The cause of Goldenhar syndrome is largely unknown. However, it is thought to be multifactorial, although there may be a genetic component, which would account for certain familial patterns. It has been suggested that there is a branchial arch development issue late in the first trimester.

An increase in Goldenhar syndrome in the children of Gulf War veterans has been suggested, but the difference was shown to be statistically insignificant.

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.

Genetic counseling for VWS involves discussion of disease transmission in the autosomal dominant manner and possibilities for penetrance and expression in offspring. Autosomal dominance means affected parents have a 50% chance of passing on their mutated "IRF6" allele to a their child. Furthermore, if a cleft patient has lip pits, he or she has a ten times greater risk of having a child with cleft lip with or without cleft palate than a cleft patient who does not have lip pits. Types of clefting between parents and affected children are significantly associated; however, different types of clefts may occur horizontally and vertically within the same pedigree. In cases where clefting is the only symptom, a complete family history must be taken to ensure the patient does not have non-syndromic clefting.

Prevalence ranges from 1 in 3500 to 5600 live births. Male-female ratio is found to be 3:2.

These lesions usually present in neonates, although they may not come to clinical attention until adulthood (for cosmetic reasons). There is no gender predilection. They are present in approximately 3-6 per 1000 live births.

TCS occurs in about one in 50,000 births in Europe. Worldwide, it is estimated to occur in one in 10,000 to one in 50,000 births.

The aneuploidy is thought to be caused by problems occurring during meiosis, either in the mother or in both the mother and father. Successive nondisjunctions have been observed in the mother of at least one patient.

The features of the syndrome likely arise due to failure of X-inactivation and the presence of multiple X chromosomes from the same parent causing problems with parental imprinting. In theory, X-inactivation should occur and leave only one X chromosome active in each cell. However, failure of this process has been observed in one individual studied. The reason for this is thought to be the presence of an unusually large, and imbalanced, number of X chromosomes interfering with the process.

The disorder can be associated with a number of psychological symptoms, anxiety, depression, social phobia, body image disorders, and patients may be subjected to discrimination, bullying and name calling especially when young. A multi-disciplinary team and parental support should include these issues.

The prevalence has been estimated at 1 in 10,000 births, but exact values are hard to know because some that have the symptoms rarely have Pierre-Robin sequence (without any other associated malformation).

Davis and Barry 1977 tested allele frequencies in domestic cats. Among the 265 cats observed, there were 101 males and 164 females. Only one cat was recorded to have the ectrodactyly abnormality, illustrating this rare disease.

According to M.P. Ferreira, a case of ectrodactyly was found in a two-month-old male mixed Terrier dog. In another study, Carrig and co-workers also reported a series of 14 dogs with this abnormality proving that although ectrodactyly is an uncommon occurrence for dogs, it is not entirely unheard of.

A large number of human gene defects can cause ectrodactyly. The most common mode of inheritance is autosomal dominant with reduced penetrance, while autosomal recessive and X-linked forms occur more rarely. Ectrodactyly can also be caused by a duplication on 10q24. Detailed studies of a number of mouse models for ectrodactyly have also revealed that a failure to maintain median apical ectodermal ridge (AER) signalling can be the main pathogenic mechanism in triggering this abnormality.

A number of factors make the identification of the genetic defects underlying human ectrodactyly a complicated process: the limited number of families linked to each split hand/foot malformation (SHFM) locus, the large number of morphogens involved in limb development, the complex interactions between these morphogens, the involvement of modifier genes, and the presumed involvement of multiple gene or long-range regulatory elements in some cases of ectrodactyly. In the clinical setting these genetic characteristics can become problematic and making predictions of carrier status and severity of the disease impossible to predict.

In 2011, a novel mutation in DLX5 was found to be involved in SHFM.

Ectrodactyly is frequently seen with other congenital anomalies. Syndromes in which ectrodactyly is associated with other abnormalities can occur when two or more genes are affected by a chromosomal rearrangement. Disorders associated with ectrodactyly include Ectrodactyly-Ectodermal Dysplasia-Clefting (EEC) syndrome, which is closely correlated to the ADULT syndrome and Limb-mammary (LMS) syndrome, Ectrodactyly-Cleft Palate (ECP) syndrome, Ectrodactyly-Ectodermal Dysplasia-Macular Dystrophy syndrome, Ectrodactyly-Fibular Aplasia/Hypoplasia (EFA) syndrome, and Ectrodactyly-Polydactyly. More than 50 syndromes and associations involving ectrodactyly are distinguished in the London Dysmorphology Database.

Lip pits may be surgically removed either for aesthetic reasons or discomfort due to inflammation caused by bacterial infections or chronic saliva excretion, though spontaneous shrinkage of the lip pits has occurred in some rare cases. Chronic inflammation has also been reported to cause squamous-cell carcinoma. It is essential to completely remove the entire lip pit canal, as mucoid cysts can develop if mucous glands are not removed. A possible side effect of removing the lip pits is a loose lip muscle. Other conditions associated with VWS, including CL, CP, congenital heart defects, etc. are surgically corrected or otherwise treated as they would be if they were non-syndromic.

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

Since the symptoms caused by this disease are present at birth, there is no “cure.” The best cure that scientists are researching is awareness and genetic testing to determine risk factors and increase knowledgeable family planning. Prevention is the only option at this point in time for a cure.

The diagnosis of PPS has been made in several ethnic groups, including Caucasian, Japanese, and sub-Saharan African. Males and females are equally likely to suffer from the syndrome. Since the disorder is very rare, its incidence rate is difficult to estimate, but is less than 1 in 10,000.

Amniotic banding affects approximately 1 in 1,200 live births. It is also believed to be the cause of 178 in 10,000 miscarriages. Up to 50% of cases have other congenital anomalies including cleft lip, cleft palate, and clubfoot deformity. Hand and finger anomalies occur in up to 80%.

Environmental influences may also cause, or interact with genetics to produce, orofacial clefting. An example of how environmental factors might be linked to genetics comes from research on mutations in the gene "PHF8" that cause cleft lip/palate (see above). It was found that PHF8 encodes for a histone lysine demethylase, and is involved in epigenetic regulation. The catalytic activity of PHF8 depends on molecular oxygen, a fact considered important with respect to reports on increased incidence of cleft lip/palate in mice that have been exposed to hypoxia early during pregnancy. In humans, fetal cleft lip and other congenital abnormalities have also been linked to maternal hypoxia, as caused by e.g. maternal smoking, maternal alcohol abuse or some forms of maternal hypertension treatment. Other environmental factors that have been studied include: seasonal causes (such as pesticide exposure); maternal diet and vitamin intake; retinoids — which are members of the vitamin A family; anticonvulsant drugs; nitrate compounds; organic solvents; parental exposure to lead; alcohol; cigarette use; and a number of other psychoactive drugs (e.g. cocaine, crack cocaine, heroin).

Current research continues to investigate the extent to which folic acid can reduce the incidence of clefting.

The prognosis depends on the location and severity of the constricting bands. Every case is different and multiple bands may be entangled around the fetus.

Bands which wrap around fingers and toes can result in syndactyly or amputations of the digits. In other instances, bands can wrap around limbs causing restriction of movement resulting in clubbed feet. In more severe cases, the bands can constrict the limb causing decreased blood supply and amputation. Amniotic bands can also sometimes attach to the face or neck causing deformities such as cleft lip and palate. If the bands become wrapped around the head or umbilical cord it can be life-threatening for the fetus.

The number of cases of miscarriage that can be attributed to ABS is unknown, although it has been reported that it may be the cause of 178 in 10,000 miscarriages.

Some characteristics of Abruzzo–Erickson syndrome include deafness, protruding ears, coloboma, a cleft palate or palatal rugosity, and short stature.

It was characterized in 1977.

49,XXXXX, also known as pentasomy X, penta X, or XXXXX syndrome, is a chromosomal aneuploidy where females have five X chromosomes rather than the normal two. It is unclear exactly how rare it is, but it appears to affect fewer than 1 in 100,000 women.

When an individual is born with phocomelia due to drugs or pharmaceuticals, it is known as thalidomide syndrome. The symptoms of thalidomide syndrome are defined by absent or shortened limbs; causing flipper hands and feet. According to Anthony J Perri III, and Sylvia Hsu they can additionally receive:

- Palsy disorder of the face

- Ear and eye abnormalities; resulting in limited/complete loss of hearing or sight

- Gastrointestinal and genitourinary tract disorders

- Ingrown genitalia

- Undeveloped/missing lungs

- Distorted digestive tract, heart, kidney

- disorders to the limbs

The infants that were exposed to thalidomide during development phases had a 40% chance of survival. The McMredie-McBride hypothesis explains that the limbs of the infants become malformed as a result of the thalidomide harming the neural tissue—simply because the neural tissue has such a large impact on formation and development of the limbs.

Minor physical anomalies (MPAs) are relatively minor (typically painless and, in themselves, harmless) congenital physical abnormalities consisting of features such as low-set ears, single transverse palmar crease, telecanthus, micrognathism, macrocephaly, hypotonia and furrowed tongue. While MPAs may have a genetic basis, they might also be caused by factors in the fetal environment: anoxia, bleeding, or infection. MPAs have been linked to disorders of pregnancy and are thought by some to be a marker for insults to the fetal neural development towards the end of the first trimester. Thus, in the neurodevelopmental literature, they are seen as indirect indications of inferferences with brain development.

MPAs have been studied in autism, Down syndrome, and in schizophrenia. A 2008 meta-analysis found that MPAs are significantly increased in the autistic population. A 1998 study found that 60% of its schizophrenic sample and 38% of their siblings had 6 or more MPAs (especially in the craniofacial area), while only 5% of the control group showed that many.

The most often cited MPA, high arched palate, is described in articles as a microform of a cleft palate. Cleft palates are partly attributable to hypoxia. The vaulted palate caused by nasal obstruction and consequent mouth breathing, without the lateralising effect of the tongue, can produce hypoxia at night.

Other MPAs are reported only sporadically. Capillary malformation is induced by RASA1 mutation and can be changed by hypoxia. A study in the American Journal of Psychiatry by Trixler et al.: found hemangiomas to be highly significant in schizophrenia. Exotropia is reported as having low correlation and high significance as well. It can be caused by perinatal hypoxia.

Ho–Kaufman–Mcalister syndrome, also known as the Chen-Kung Ho–Kaufman–Mcalister syndrome, is a rare congenital malformation syndrome where infants are born with a cleft palate, micrognathia, Wormian bones, congenital heart disease, dislocated hips, bowed fibulae, preaxial polydactyly of the feet, abnormal skin patterns, and most prominently, missing tibia. The etiology is unknown. Ho–Kaufman–Mcalister syndrome is named after Chen-Kung Ho, R.L. Kaufman, and W.H. Mcalister who first described the syndrome in 1975 at Washington University in St. Louis. It is considered a rare disease by the Office of Rare Diseases (ORD) of the National Institutes of Health (NIH).

According to National Organization for Rare Disorders (NORD): when phocomelia is transmitted [in its familial genetic form] it is seen as an autosomal recessive trait and the mutation is linked to chromosome 8.

A study of Roberts Syndrome, a genetic disorder showing similar symptoms to phocomelia, has shed light on the possible causes. An individual afflicted with Roberts Syndrome will have chromosome copies that do not connect at the centromeres, making them unable to line up accordingly. As a result, the newly made cells contain an excess or reduced number of chromosomes. In both Roberts Syndrome and phocomelia the cells cease to develop, or die, preventing proper development of the limbs, eyes, brain, palate, or other structures.