There is still some discussion on whether FND is sporadic or genetic. The majority of FND cases are sporadic. Yet, some studies describe families with multiple members with FND. Gene mutations are likely to play an important role in the cause. Unfortunately, the genetic cause for most types of FND remains undetermined.

OAFNS is a combination of FND and oculo-auriculo-vertebral spectrum (OAVS).

The diagnosis of OAVS is based on the following facial characteristics: microtia (underdeveloped external ear), preauricular tags, facial asymmetry, mandibular hypoplasia and epibulbar lipodermoids (benign tumor of the eye which consists of adipose and fibrous tissue).

There still remains discussion about the classification and the minimal amount of characteristics. When someone presents with FND and the characteristics of OAVS, the diagnosis OAFNS may be made.

As the incidence of OAFNS is unknown, there are probably a lot of children with mild phenotypes that aren’t being diagnosed as being OAFNS.

The cause of OAFNS is unknown, but there are some theories about the genesis. Autosomal recessive inheritance is suggested because of a case with two affected siblings and a case with consanguineous parents. However, another study shows that it is more plausible that OAFNS is sporadic.

It is known that maternal diabetes plays a role in developing malformations of craniofacial structures and in OAVS. Therefore, it is suggested as a cause of OAFNS. Folate deficiency is also suggested as possible mechanism.

Low-dose CT protocols should be considered in diagnosing children with OAFNS.

Macrostomia, (from the Greek prefix "makro-" meaning "large" and from Greek , "mouth") refers to a mouth that is unusually wide.

Macrostomia is characterized as a physical abnormality that causes clefts to form on the face of affected individuals. These clefts can form on either or both sides of the face, but they are most commonly seen on the right cheek and have a higher rate of occurrence in males. Macrostomia is very irregular and on average occurs only once in every 150,000 to 300,000 live births. It's unusual for macrostomia to occur on its own and it is included as a symptom for many diseases including craniofacial microsomia. The clefts result from improper development and fusion of the mandibular and maxillary processes. The clefts cause problems with facial muscle development. The origin of macrostomia is not yet fully understood it could have multiple causes.

Surgery is needed to prevent the closing of the coronal sutures from damaging brain development. In particular, surgeries for the LeFort III or monobloc midface distraction osteogenesis which detaches the midface or the entire upper face, respectively, from the rest of the skull, are performed in order to reposition them in the correct plane. These surgeries are performed by both plastic and oral and maxillofacial (OMS) surgeons, often in collaboration.

Via a photo shown on a Facebook page, the mother of a child previously diagnosed with this condition recognised the symptoms and reported them to the family involved, resulting in an immediate diagnosis that medical professionals had overlooked in all earlier consultations.

Prosthetic replacement of missing teeth is possible using dental implant technology or dentures. This treatment can be successful in giving patients with anodontia a more aesthetically pleasing appearance. The use of an implant prosthesis in the lower jaw could be recommended for younger patients as it is shown to significantly improve the craniofacial growth, social development and self-image. The study associated with this evidence worked with individuals who had ectodermal dysplasia of varying age groups of up to 11, 11 to 18 and more than 18 years. It was noted that the risk of implant failure was significantly higher in patients younger than 18 years, but there is significant reason to use this methodology of treatment in those older. Overall the use of an implant-prosthesis has a considerable functional, aesthetic and psychological advantage when compared to a conventional denture, in the patients.

There are 4 distinct variations of macrostomia. Classifications are a complete lateral facial cleft, simple macrostomia, macrostomia with diastasis of the facial musculature, and isolated facial musculature diastasis. Each has a different physical appearance with varying levels of severity.

The cleft associated with macrostomia is associated with improper or failed fusion of the mandibular and maxillary processes during embryonic development. This can lead to a variety of abnormalities involving skin, subcutaneous tissue, facial muscles, and the mucous membrane. The severity of each abnormality can vary from minor to severe. Environmental contaminants may play a role in causing macrostomia. Many affected individuals were found in Lagos, an industrial area of Nigeria, where water supplies are known to be contaminated by improper disposal of industrial and domestic waste.

The reported incidence of constriction ring syndrome varies from 1/1200 and 1/15000 live births. The prevalence is equally in male and female.

Fetomaternal factors like prematurity, maternal illnes, low birth weight and maternal drug exposure are predisposing factors for the constriction ring syndrome.

No positive relationship between CRS and genetic inheritance has been reported.

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 incidence of metopic synostosis is roughly between 1:700 and 1:15.000 newborns globally (differs per country). Trigonocephaly is seen more in males than females ranging from 2:1 to 6,5:1. Hereditary relations in metopic synostosis have been found of which 5,5% were well defined syndromic. Maternal age and a birth weight of less than 2500g may also play a role in trigonocephaly. These data are based on estimations and do not give factual information.

Only one article gives valuable and reliable information regarding the incidence of metopic synsostosis in the Netherlands. The incidence in the Netherlands showed an increase from 0.6 (1997) to 1.9 (2007) for every 10.000 live births.

In dentistry, anodontia, also called anodontia vera, is a rare genetic disorder characterized by the congenital absence of all primary or permanent teeth. It is associated with the group of skin and nerve syndromes called the ectodermal dysplasias. Anodontia is usually part of a syndrome and seldom occurs as an isolated entity.

Congenital absence of permanent teeth can present as hypodontia, usually missing 1 or 2 permanent teeth, or oligodontia that is the congenital absence of 6 or more teeth. Congenital absence of all wisdom teeth, or third molars, is relatively common. Anodontia is the congenital absence of teeth and can occur in some or all teeth (partial anodontia or hypodontia), involve two dentitions or only teeth of the permanent dentition (Dorland's 1998). Approximately 1% of the population suffers from oligodontia. Many denominations are attributed to this anomaly: partial anodontia, hypodontia, oligodontia, the congenital absence, anodontia, bilateral aplasia. Anodontia being the term used in controlled vocabulary Medical Subject Headings (MeSH) from MEDLINE which was developed by the United States National Library of Medicine. The congenital absence of at least one permanent tooth is the most common dental anomaly and may contribute to masticator dysfunction, speech impairment, aesthetic problems, and malocclusion (Shapiro and Farrington 1983). Absence of lateral incisors represents a major stereotype. Individuals with this condition are perceived as socially most aggressive compared with people without anodontia (Shaw 1981).

Midline cervical clefts are a rare congenital anomaly resulting from incomplete fusion during embryogenesis of the first and second branchial arches in the ventral midline of the neck. The condition presents as a midline cutaneous defect of the anterior neck with a skin projection or sinus, or as a subcutaneous erythematous fibrous cord. Surgical excision is the preferred treatment.

The incidence of VACTERL association is estimated to be approximately 1 in 10,000 to 1 in 40,000 live-born infants. It is seen more frequently in infants born to diabetic mothers. While most cases are sporadic, there are clearly families who present with multiple involved members.

Patients with abnormal cardiac and kidney function may be more at risk for hemolytic uremic syndrome

The phenomenon of tooth fusion arises through union of two normally separated tooth germs, and depending upon the stage of development of the teeth at the time of union, it may be either complete or incomplete. On some occasions, two independent pulp chambers and root canals can be seen. However, fusion can also be the union of a normal tooth bud to a supernumerary tooth germ. In these cases, the number of teeth is fewer if the anomalous tooth is counted as one tooth. In geminated teeth, division is usually incomplete and results in a large tooth crown that has a single root and a single canal. Both gemination and fusion are prevalent in primary dentition, with incisors being more affected.

Tooth gemination, in contrast to fusion, arises when two teeth develop from one tooth bud. When the anomalous tooth appears to be two separate teeth, it appears that the patient has an extra tooth, although they have a normal number of tooth roots.

Surgical correction is recommended when a constriction ring results in a limb contour deformity, with or without lymphedema.

Sternal clefts are rare congenital malformations that result from defective embryologic fusion of paired mesodermal bands in the ventral midline. They may be associated with other midline defects (as in pentalogy of Cantrell). It may also occur in isolation. Sternal cleft is treated by surgery in early life to avoid fixation leading to immobility.

The prevalence of Klippel–Feil syndrome is unknown due to the fact that there was no study done to determine the true prevalence.

Although the actual occurrence for the KFS syndrome is unknown, it is estimated to occur 1 in 40,000 to 42,000 newborns worldwide. In addition, females seem to be affected slightly more often than males.

Focal facial dermal dysplasia (FFDD) is a rare genetically heterogeneous group of disorders that are characterized by congenital bilateral scar like facial lesions, with or without associated facial anomalies. It is characterized by hairless lesions with fingerprint like puckering of the skin, especially at the temples, due to alternating bands of dermal and epidermal atrophy.

This condition is also known as Brauer syndrome (hereditary symmetrical aplastic nevi of temples, bitemporal aplasia cutis congenita, bitemporal aplasia cutis congenita: OMIM ) and Setleis syndrome (facial ectodermal dysplasia: OMIM ).

Anotia ("no ear") describes a rare congenital deformity that involves the complete absence of the pinna, the outer projected portion of the ear, and narrowing or absence of the ear canal. This contrasts with microtia, in which a small part of the pinna is present. Anotia and microtia may occur unilaterally (only one ear affected) or bilaterally (both ears affected). This deformity results in conductive hearing loss, deafness.

The condition arises from some factor or set of factors present during approximately the 3rd week to 7th week of fetal development. Formation of the sacrum/lower back and corresponding nervous system is usually nearing completion by the 4th week of development. Due to abnormal gastrulation, the mesoderm migration is disturbed. This disturbance results in symptoms varying from minor lesions of the lower vertebrae to more severe symptoms such as complete fusion of the lower limbs. While the exact cause is unknown, it has been speculated that the condition may be associated with certain dietary deficiencies including a lack or insufficient amounts of folic acid.

Sacral agenesis syndrome (agenesis of the lumbar spine, sacrum, and coccyx, and hypoplasia of the lower extremities) is a well-established congenital anomaly associated with maternal diabetes mellitus (not gestational diabetes). However, other causes are presumably involved, as demonstrated by the rare incidence of caudal regression syndrome (1:60,000) compared to diabetes.

The dominant inherited sacral agenesis (also referred to as Currarino syndrome) is very often correlated with a mutation in the Hb9 (also called HlxB9) gene (shown by Sally Ann Lynch, 1995, Nature Genetics).

It may be the cause of sirenomelia ("Mermaid syndrome").

The heterogeneity of the Klippel–Feil syndrome has made it difficult to outline the diagnosis as well as the prognosis classes for this disease. Because of this, it has complicated the exact explanation of the genetic cause of the syndrome.

The prognosis for most individuals with KFS is good if the disorder is treated early on and appropriately. Activities that can injure the neck should be avoided, as it may contribute to further damage. Other diseases associated with the syndrome can be fatal if not treated, or if found too late to be treatable.

Caudal regression syndrome or sacral agenesis (or hypoplasia of the sacrum) is a congenital disorder in which there is abnormal fetal development of the lower spine—the caudal partition of the spine.

It occurs at a rate of approximately one per 25,000 live births.

Type II appears to be due to mutations in the transcription factor TWIST2 on chromosome 2.

Type IV is due to mutations in the Cyp26c1 gene.

Radioulnar synostosis is one of the more common failures of separation of parts of the upper limb. There are two general types: one is characterized by fusion of the radius and ulna at their proximal borders and the other is fused distal to the proximal radial epiphysis. Most cases are sporadic, congenital (due to a defect in longitudinal segmentation at the 7th week of development) and less often post-traumatic, bilateral in 60%, and more common in males. Familial cases in association with autosomal dominant transmission appear to be concentrated in certain geographic regions, such as Sicily.

The condition frequently is not noted until late childhood, as function may be normal, especially in unilateral cases. Increased wrist motion may compensate for the absent forearm motion. It has been suggested that individuals whose forearms are fixed in greater amounts of pronation (over 60 degrees) face more problems with function than those with around 20 degrees of fixation. Pain is generally not a problem, unless radial head dislocation should occur.

Most examples of radioulnar synostosis are isolated (non-syndromic). Syndromes that may be accompanied by radioulnar synostosis include X chromosome polyploidy (e.g., XXXY) and other chromosome disorders (e.g., 4p- syndrome, Williams syndrome), acrofacial dysostosis, Antley–Bixler syndrome, genitopatellar syndrome, Greig cephalopolysyndactyly syndrome, hereditary multiple osteochondromas (hereditary multiple exostoses), limb-body wall complex, and Nievergelt syndrome.

Craniosynostosis (from cranio, cranium; + syn, together; + ostosis relating to bone) is a condition in which one or more of the fibrous sutures in an infant skull prematurely fuses by turning into bone (ossification). Craniosynostosis has following kinds: scaphocephaly, trigonocephaly, plagiocephaly, anterior plagiocephaly, posterior plagiocephaly, brachycephaly, oxycephaly, pansynostosis.