Facial features found in this syndrome include

- dolichocephaly

- hypertelorism

- ptosis

- microretrognathia

- high arched palate

- long flat philtrum

- low set ears

Non facial features of this syndrome include

- hyperextensibility

- hypotonia

- lateral meningoceles

The lateral meningocoles are a common finding in this syndrome. They may be associated with neurological abnormalities and result in bladder dysfunction and neuropathy.

In medicine, a sequence is a series of ordered consequences due to a single cause.

It differs from a syndrome in that seriality is more predictable: if A causes B, and B causes C, and C causes D, then D would not be seen if C is not seen. However, in less formal contexts, the term "syndrome" is sometimes used instead of sequence.

Examples include:

- oligohydramnios sequence (also known as Potter sequence)

- Pierre Robin sequence

- Poland sequence

The failure of the metanephros to develop in cases of BRA and some cases involving unilateral renal agenesis (URA) is due primarily to the failure of the mesonephric duct to produce a ureteric bud capable of inducing the metanephric mesenchyme. The failed induction will thereby cause the subsequent degeneration of the metanephros by apoptosis and other mechanisms. The mesonephric duct(s) of the agenic kidney(s) will also degenerate and fail to connect with the bladder. Therefore, the means by which the fetus produces urine and transports it to the bladder for excretion into the amniotic sac has been severely compromised (in the cases of URA), or completely eliminated (in the cases of BRA). The decreased volume of amniotic fluid causes the growing fetus to become compressed by the mother's uterus. This compression can cause many physical deformities of the fetus, most common of which is Potter facies. Lower extremity anomalies are frequent in these cases, which often presents with clubbed feet and/or bowing of the legs. Sirenomelia, or "Mermaid syndrome" (which occurs approximately in 1:45,000 births) can also present. In fact, nearly all reported cases of sirenomelia also be present with BRA.

Other anomalies of the classic Potter sequence infant include a parrot beak nose, redundant skin, and the most common characteristic of infants with BRA which is a skin fold of tissue extending from the medial canthus across the cheek. The ears are slightly low and pressed against the head making them appear large. The adrenal glands often appear as small oval discs pressed against the posterior abdomen due to the absence of upward renal pressure. The bladder is often small, nondistensible and may be filled with a minute amount of fluid. In males the vas deferens and seminal vesicles may be absent, while in females the uterus and upper vagina may be absent. Other abnormalities include anal atresia, absence of the rectum and sigmoid colon, esophageal and duodenal atresia, and a single umbilical artery. Presence of a diaphragmatic hernia is also common in these fetuses/infants. Additionally, the alveolar sacs of the lungs fail to properly develop as a result of the reduced volume of amniotic fluid. Labor is often induced between 22 and 36 weeks of gestation (however, some of these pregnancies may go to term) and unaborted infants typically survive for only a few minutes to a few hours. These infants will eventually die as either a result of pulmonary hypoplasia or renal failure.

Recognised symptoms up till now are:

- Autism or autistic behaviors

- ADHD

- Learning disability

- Large head

- Dysmorphic facial appearance - mild

- Prominent forehead

- Wide-set eyes (hypertelorism)

- Schizophrenia

- Loose joints

- GERD

- Sleep disturbances

- Sleep Apnea

- Underdeveloped parts of brain - corpus callosum and cerebellar vermis

- Neuroblastoma

- Speech & developmental delays

- Chiari malformation of the brain

- Congenital heart defects

- Hypotonia

It is not clear whether the list of symptoms is complete. Very little information is known about the syndrome. The symptomology may be different among individuals, even in the same family.

Physical Symptoms

- Heart Defects

- Characteristics of Autism

- Genital defects (in males)

- Childhood hypotonia

- Respiratory infections

- Motor Delay

- Renal defects

Behavioural Symptoms

- Passiveness

- Sociability

- Aggression

- Biting, and/or hitting

- Moodiness

- Disliking routine changes

The three most common symptoms of Opitz G/BBB syndrome (both type I & II) are hypertelorism (exceptionally wide-spaced eyes), laryngo-tracheo-esophalgeal defects (including clefts and holes in the palate, larynx, trachea and esophagus) and hypospadias (urinary openings in males not at the tip of the penis) (Meroni, Opitz G/BBB syndrome, 2012). Abnormalities in the larynx, trachea and esophagus can cause significant difficulty breathing and/or swallowing and can result in reoccurring pneumonia and life-threatening situations. Commonly, there may be a gap between the trachea and esophagus, referred to as a laryngeal cleft; which can allow food or fluid to enter the airway and make breathing and eating a difficult task.

Genital abnormalities like a urinary opening under the penis (hypospadias), undescended testes (cryptorchidism), underdeveloped scrotum and a scrotum divided into two lobes (bifid scrotum) can all be commonplace for males with the disease.

Developmental delays of the brain and nervous system are also common in both types I and II of the disease. 50% of people with Opitz G/BBB Syndrome will experience developmental delay and mild intellectual disability. This can impact motor skills, speech and learning capabilities. Some of these instances are likened to autistic spectrum disorders. Close to half of the people with Opitz G/BBB Syndrome also have a cleft lip (hole in the lip opening) and possibly a cleft palate (hole in the roof of the mouth), as well. Less than half of the people diagnosed have heart defects, imperforate anus (obstructed anal opening), and brain defects. Of all the impairments, female carriers of X-linked Type I Opitz G/BBB Syndrome usually only have ocular hypertelorism.

Craniofacial and other features of LFS include: maxillary hypoplasia (underdevelopment of the upper jaw bone), a small mandible (lower jaw bone) and receding chin, a high-arched palate (the roof of the mouth), with crowding and misalignment of the upper teeth; macrocephaly (enlarged skull) with a prominent forehead, hypernasal speech (voice), a long nose with a high, narrow nasal bridge; a deep, short philtrum (the indentation in the upper lip, beneath the nose), low-set ears with some apparent retroversion, hypotonia (decreased muscle tone), pectus excavatum (a malformity of the chest), slightly enlarged to normal testicular size in males, and seizures.

Hypernasal speech, or "hypernasality", is primarily the result of velopharyngeal insufficiency, a sometimes congenital aberration in which the velopharyngeal sphincter allows too much air into the nasal cavity during speech. In LFS, hypernasality may also be caused by failure of the soft palate and uvula to reach the back wall of the pharynx (the interior cavity of the throat where swallowing generally occurs) during speech, a condition that can be associated with a submucosal cleft palate.

LFS is clinically distinguished from other X-linked forms of intellectual disability by the accompanying presence of marfanoid habitus. Marfanoid habitus describes a group of physical features common to Marfan syndrome. Including Marfan syndrome and LFS, marfanoid features of this type have also been observed with several other disorders, one of which is multiple endocrine neoplasia type 2.

In LFS, specific features identified as marfanoid include: a long, narrow face; tall, thin stature; long, slender limbs, fingers and toes (not unlike arachnodactyly) with joint hyperextensibility, shortened halluces (the big toes) and long second toes.

The diagnosis of marfanoid habitus in LFS is often delayed because many of the physical features and characteristics associated with it are usually not evident until adolescence.

Twin anemia-polycythemia sequence, abbreviated as TAPS, is a form of chronic inter-twin transfusion.

Potter sequence is the atypical physical appearance of a baby due to oligohydramnios experienced when in the uterus. It includes clubbed feet, pulmonary hypoplasia and cranial anomalies related to the oligohydramnios. Oligohydramnios is the decrease in amniotic fluid volume sufficient to cause deformations in morphogenesis of the baby.

Oligohydramnios is the cause of Potter sequence but there are many things that can lead to oligohydramnios. It can be caused by renal diseases such as bilateral renal agenesis (BRA), atresia of the ureter or urethra causing obstruction of the urinary tract, polycystic or multicystic kidney diseases, renal hypoplasia, amniotic rupture, toxemia, or uteroplacental insufficiency from maternal hypertension.

The term "Potter sequence" was initially intended to only refer to cases caused by BRA; however, it is now commonly used by many clinicians and researchers to refer to any case that presents with oligohydramnios or anhydramnios regardless of the source of the loss of amniotic fluid.

X-linked type I Opitz G/BBB Syndrome is diagnosed on clinical findings, but those findings can vary greatly: even within the same family. Manifestations of X-linked type I are classified in the frequent/major findings and minor findings that are found in less than 50% of individuals.

The three major findings that suggest a person has X-linked Type I Opitz G/BBB Syndrome:

1. Ocular hypertelorism (~100% cases)

2. Hypospadias (85-90% cases)

3. Laryngotracheoesophageal abnormalities (60-70%)

Minor findings found in less than 50% of individuals:

1. Developmental delay (especially intellectually)

2. Cleft lip/palate

3. Congenital heart defects

4. Imperforate (blocked) anus

5. Brain defects (especially corpus callosum)

In 1989, Hogdall used ultrasonographs to diagnose X-linked Type I Opitz G/BBB Syndrome after 19 weeks of pregnancy, by identifying hypertelorism (widely-spaced eyes) and hypospadias (irregular urinary tract openings in the penis).

There is also molecular genetic testing available to identify mutations leading to Opitz G/BBB Syndrome. X-linked Type I testing must be done on MID1, since this is the only gene that is known to cause Type I Opitz G/BBB Syndrome. Two different tests can be performed: sequence analysis and deletion/duplication analysis. In the sequence analysis a positive result would detect 15-50% of the DNA sequence mutated, while a deletion/duplication positive result would find deletion or duplication of one or more exons of the entire MID1 gene.

Aphalangy, hemivertebrae and urogenital-intestinal dysgenesis is an extremely rare syndrome, described only in three siblings. It associates hypoplasia or aplasia of phalanges of hands and feet, hemivertebrae and various urogenital and/or intestinal abnormalities. Intrafamilial variability is important as one sister had lethal abnormalities (Potter sequence and pulmonary hypoplasia), while her affected brother was in good health with normal psychomotor development at 6 months of age. Prognosis seems to depend mainly on the severity of visceral malformations. Etiology and inheritance remain unknown.

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

Pierre Robin syndrome (abbreviated to PRS, and also known as Pierre Robin sequence, Pierre Robin malformation, Pierre Robin anomaly or Pierre Robin anomalad) is a congenital condition of facial abnormalities in humans. PRS is a sequence, i.e. a chain of certain developmental malformations, one entailing the next. The three main features are cleft palate, retrognathia (abnormal positioning of the jaw or mandible) and glossoptosis (airway obstruction caused by backwards displacement of the tongue base). A genetic cause to PRS was recently identified. Pierre Robin sequence may be caused by genetic anomalies at chromosomes 2, 11, or 17.

PRS is characterized by an unusually small mandible (micrognathia), posterior displacement or retraction of the tongue (glossoptosis), and upper airway obstruction. Incomplete closure of the roof of the mouth (cleft palate) is present in the majority of patients, and is commonly U-shaped.

People with the combination of Duane anomaly and radial ray malformations may have a variety of other signs and symptoms. These features include:

- Unusually shaped ears

- Hearing loss

- Heart and kidney defects

- A distinctive facial appearance

- An inward- and downward-turning foot (a clubfoot)

- Fused vertebrae.

Infants with Catel–Manzke syndrome have an extra (supernumerary), irregularly shaped bone known as a Hyperphalangy located between the first bone of the index finger (proximal phalanx) and the corresponding bone within the body of the hand (second metacarpal). As a result, the index fingers may be fixed in an abnormally bent position (clinodactyly). In some rare cases, additional abnormalities of the hands may also be present. Due to the presence of micrognathia, glossoptosis, and cleft palate, affected infants may have feeding and breathing difficulties; growth deficiency; consistent middle ear infections (otitis media); and other complications.

In addition, some infants with the syndrome may have structural abnormalities of the heart that are present at birth (congenital heart defects). The range and severity of symptoms and findings may vary from case to case. Catel–Manzke syndrome usually appears to occur randomly, for unknown sporadic reasons.

The most common and defining features of BGS are craniosynostosis and radial ray deficiency. The observations of these features allow for a diagnosis of BGS to be made, as these symptoms characterize the syndrome. Craniosynostosis involves the pre-mature fusion of bones in the skull. The coronal craniosynostosis that is commonly seen in patients with BGS results in the fusion of the skull along the coronal suture. Because of the changes in how the bones of the skull are connected together, people with BGS will have an abnormally shaped head, known as brachycephaly. Features commonly seen in those with coronal craniosynostosis are bulging eyes, shallow eye pockets, and a prominent forehead. Radial ray deficiency is another clinical characteristic of those with BGS, and results in the under-development (hypoplasia) or the absence (aplasia) of the bones in the arms and the hands. These bones include the radius, the carpal bones associated with the radius and the thumb. Oligodactyly can also result from radial ray deficiency, meaning that someone with BGS may have fewer than five fingers. Radial ray deficiency that is associated with syndromes (such as BGS) occurs bi-laterally, affecting both arms.

Some of the other clinical characteristics sometimes associated with this disorder are growth retardation and poikiloderma. Although the presentation of BGS may differ between individuals, these characteristics are often observed. People with BGS may have stunted growth, short stature and misshapen kneecaps. Poikiloderma may also be present in people with this syndrome, meaning that their skin may have regions of hyperpigmentation and hypopigmentation, or regions where the skin is missing (atrophy).

This is characterized by hand and arm abnormalities. The following are specific characteristics:

- Malformed or absent (aplasia) thumb

- A thumb that looks more like a finger

- Partial or complete absence of a radius

- Shortening and radial deviation of the forearms

- Triphalangeal thumb

- Duplication of the thumb (preaxial polydactyly)

For individuals with MORM syndrome, symptoms do not appear until about one year into the child’s life span. From conception to birth, individuals with MORM syndrome appear asymptotic with no abnormal characteristics. Vision is negatively affected within the first year of life, particularly night vision. Individuals with MORM syndrome experience decreased visual acuity meaning their ability to see distinct sharp lines decreases. Vision quality continues to deteriorate until age three. Any further reduction in vision acuity is not observed until the individual is between the ages thirty to forty. Delayed sentence processing and intellectual disability is associated with individuals with MORM syndrome, primarily observed at age four. Individuals continue to develop and grow until they are five to twelve years old. During this age bracket, truncal obesity can develop. Truncal obesity is a term used to describe the build up of fat around ones trunk or torso as opposed to the persons extremities. Males enter puberty at around age twelve and develop normally except for their sex organ. The males penis will remain at the prepubescent size resulting in a micropenis. The life span of individuals with MORM syndrome is unclear as well as the fertility of these individuals.

This is much more common, but is not usually of any major health consequence, as long as the other kidney is healthy.

It may be associated with an increased incidence of Müllerian duct abnormalities, which are abnormalities of the development of the female reproductive tract and can be a cause of infertility, blocked menstrual flow (hematocolpos), increased need for Caesarean sections, or other problems. Herlyn-Werner-Wunderlich syndrome is one such syndrome in which unilaterial renal agenesis is combined with a blind hemivagina and uterus didelphys. Up to 40% of women with a urogenital tract anomaly also have an associated renal tract anomaly.

Adults with unilateral renal agenesis have considerably higher chances of hypertension (high blood pressure). People with this condition are advised to approach contact sports with caution.

The odds of a person being born with unilateral renal agenesis are approximately 1 in 750.

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.

Affected individuals commonly suffer from photophobia, nystagmus and achromatopsia. Other symptoms affecting vision may include night vision difficulties; optic disc pallor; narrow vessels; macular atrophy with pigment mottling; peripheral deep white dot deposits or retinal pigment epithelium (RPE) alterations in the inferonasal retina; decreased foveal and retinal thickness; attenuation of retinal lamination; hyperreflectivity in the choroids (due to RPE and choriocapillaris atrophy); impairment of color vision; and progressive loss of vision with advancing age.

In line with ameleogenesis imperfecta, affected members may display teeth yellow-brown in colour, dysplastic, presenting numerous caries; reduced enamel layer prone to posteruptive failure; and abnormality of morphology involving dentine.

1q21.1 duplication syndrome or 1q21.1 (recurrent) microduplication is a rare aberration of chromosome 1.

In a common situation a human cell has one pair of identical chromosomes on chromosome 1. With the 1q21.1 duplication syndrome one chromosome of the pair is over complete, because a part of the sequence of the chromosome is duplicated twice or more. In 1q21.1, the '1' stands for chromosome 1, the 'q' stands for the long arm of the chromosome and '21.1' stands for the part of the long arm in which the duplication is situated.

Next to the duplication syndrome, there is also a 1q21.1 deletion syndrome. While there are two or three copies of a similar part of the DNA on a particular spot with the duplication syndrome, there is a part of the DNA missing with the deletion syndrome on the same spot. Literature refers to both the deletion and the duplication as the 1q21.1 copy-number variations (CNV).

The CNV leads to a very variable phenotype and the manifestations in individuals are quite variable. Some people who have the syndrome can function in a normal way, while others have symptoms of mental retardation and various physical anomalies.

Different stages of TAPS are identified using the criteria as shown in the following tables.