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A supplemental system of phenotypic grading that uses seven classes instead of the traditional three was proposed by pediatric endocrinologist Charmian A. Quigley et al. in 1995. The first six grades of the scale, grades 1 through 6, are differentiated by the degree of genital masculinization; grade 1 is indicated when the external genitalia is fully masculinized, grade 6 is indicated when the external genitalia is fully feminized, and grades 2 through 5 quantify four degrees of increasingly feminized genitalia that lie in the interim. Grade 7 is indistinguishable from grade 6 until puberty, and is thereafter differentiated by the presence of secondary terminal hair; grade 6 is indicated when secondary terminal hair is present, whereas grade 7 is indicated when it is absent. The Quigley scale can be used in conjunction with the traditional three classes of AIS to provide additional information regarding the degree of genital masculinization, and is particularly useful when the diagnosis is PAIS.
Partial androgen insensitivity syndrome is diagnosed when the degree of androgen insensitivity in an individual with a 46,XY karyotype is great enough to partially prevent the masculinization of the genitalia, but is not great enough to completely prevent genital masculinization. This includes any phenotype resulting from androgen insensitivity where the genitalia is partially, but not completely masculinized. Genital ambiguities are frequently detected during clinical examination at birth, and consequently, a PAIS diagnosis can be made during infancy as part of a differential diagnostic workup.
Pubertal undervirilization is common, including gynecomastia, decreased secondary terminal hair, and / or a high pitched voice. The phallic structure ranges from a penis with varying degrees of diminished size and hypospadias to a slightly enlarged clitoris. Wolffian structures (the epididymides, vasa deferentia, and seminal vesicles) are typically partially or fully developed. The prostate is typically small or impalpable. Müllerian remnants are rare, but have been reported.
The gonads in individuals with PAIS are testes, regardless of phenotype; during the embryonic stage of development, testes form in an androgen-independent process that occurs due to the influence of the SRY gene on the Y chromosome. Cryptorchidism is common, and carries with it a 50% risk of germ cell malignancy. If the testes are located intrascrotally, there may still be significant risk of germ cell malignancy; studies have not yet been published to assess this risk.
Predominantly male phenotypes vary in the degree of genital undermasculinization to include micropenis, chordee, scrotum, and / or pseudovaginal perineoscrotal hypospadias. Impotence may be fairly common, depending on phenotypic features; in one study of 15 males with PAIS, 80% of those interviewed indicated that they had some degree of impotence. Anejaculation appears to occur somewhat independently of impotence; some men are still able to ejaculate despite impotence, and others without erectile difficulties cannot. Predominantly female phenotypes include a variable degree of labial fusion and clitoromegaly. Ambiguous phenotypic states include a phallic structure that is intermediate between a clitoris and a penis, and a single perineal orifice that connects to both the urethra and the vagina (i.e. urogenital sinus). At birth, it may not be possible to immediately differentiate the external genitalia of individuals with PAIS as being either male or female, although the majority of individuals with PAIS are raised male.
Given the wide diversity of phenotypes associated with PAIS, the diagnosis is often further specified by assessing genital masculinization. Grades 2 through 5 of the Quigley scale quantify four degrees of increasingly feminized genitalia that correspond to PAIS.
Grade 2, the mildest form of PAIS, presents with a predominantly male phenotype that presents with minor signs of undermasculinized genitalia, such as isolated hypospadias, which can be severe. Hypospadias may manifest with a partially formed channel from the urethral opening to the glans. Until recently, it was thought that isolated micropenis was not a manifestation of PAIS. However, in 2010, two cases of PAIS manifesting with isolated micropenis were documented.
Grade 3, the most common phenotypic form of PAIS, features a predominantly male phenotype that is more severely undermasculinized, and typically presents with micropenis and pseudovaginal perineoscrotal hypospadias with scrotum.
Grade 4 presents with a gender ambiguous phenotype, including a phallic structure that is intermediate between a clitoris and a penis. The urethra typically opens into a common channel with the vagina (i.e. urogenital sinus).
Grade 5, the form of PAIS with the greatest degree of androgen insensitivity, presents with a mostly female phenotype, including separate urethral and vaginal orifices, but also shows signs of slight masculinization including mild clitoromegaly and / or partial labial fusion.
Previously, it was erroneously thought that individuals with PAIS were always infertile; at least one case report has been published that describes fertile men that fit the criteria for grade 2 PAIS (micropenis, penile hypospadias, and gynecomastia).
Spinal and bulbar muscular atrophy (SBMA), also known as Kennedy's disease, is a severe neurodegenerative syndrome that is associated with a particular mutation of the androgen receptor's polyglutamine tract called a trinucleotide repeat expansion. SBMA results when the length of the polyglutamine tract exceeds 40 repetitions.
Although technically a variant of MAIS, SBMA's presentation is not typical of androgen insensitivity; symptoms do not occur until adulthood and include neuromuscular defects as well as signs of androgen inaction. Neuromuscular symptoms include progressive proximal muscle weakness, atrophy, and fasciculations. Symptoms of androgen insensitivity experienced by men with SBMA are also progressive and include testicular atrophy, severe oligospermia or azoospermia, gynecomastia, and feminized skin changes despite elevated androgen levels. Disease onset, which usually affects the proximal musculature first, occurs in the third to fifth decades of life, and is often preceded by muscular cramps on exertion, tremor of the hands, and elevated muscle creatine kinase. SBMA is often misdiagnosed as amyotrophic lateral sclerosis (ALS) (also known as Lou Gehrig's disease).
The symptoms of SBMA are thought to be brought about by two simultaneous pathways involving the toxic misfolding of proteins and loss of AR functionality. The polyglutamine tract in affected pedigrees tends to increase in length over generations, a phenomenon known as "anticipation", leading to an increase in the severity of the disease as well as a decrease in the age of onset for each subsequent generation of a family affected by SBMA.
Individuals with mild (or minimal) androgen insensitivity syndrome (grade 1 on the Quigley scale) are born phenotypically male, with fully masculinized genitalia; this category of androgen insensitivity is diagnosed when the degree of androgen insensitivity in an individual with a 46,XY karyotype is great enough to impair virilization or spermatogenesis, but is not great enough to impair normal male genital development. MAIS is the mildest and least known form of androgen insensitivity syndrome.
The existence of a variant of androgen insensitivity that solely affected spermatogenesis was theoretical at first. Cases of phenotypically normal males with isolated spermatogenic defect due to AR mutation were first detected as the result of male infertility evaluations. Until then, early evidence in support of the existence of MAIS was limited to cases involving a mild defect in virilization, although some of these early cases made allowances for some degree of impairment of genital masculinization, such as hypospadias or micropenis. It is estimated that 2-3% of infertile men have AR gene mutations.
Examples of MAIS phenotypes include isolated infertility (oligospermia or azoospermia), mild gynecomastia in young adulthood, decreased secondary terminal hair, high pitched voice, or minor hypospadias repair in childhood. The external male genitalia (penis, scrotum, and urethra) are otherwise normal in individuals with MAIS. Internal genitalia, including Wolffian structures (the epididymides, vasa deferentia, and seminal vesicles) and the prostate, is also normal, although the bitesticular volume of infertile men (both with and without MAIS) is diminished; male infertility is associated with reduced bitesticular volume, varicocele, retractile testes, low ejaculate volume, male accessory gland infections (MAGI), and mumps orchitis. The incidence of these features in infertile men with MAIS is similar to that of infertile men without MAIS. MAIS is not associated with Müllerian remnants.
All forms of androgen insensitivity are associated with infertility, though exceptions have been reported for both the mild and partial forms.
PAIS is associated with a 50% risk of germ cell malignancy when the testes are undescended. If the testes are located intrascrotally, there may still be significant risk of germ cell malignancy; studies have not yet been published to assess this risk. Some men with PAIS may experience sexual dysfunction including impotence and anejaculation. A few AR mutations that cause PAIS are also associated with prostate and breast cancers.
Vaginal hypoplasia, a relatively frequent finding in CAIS and some forms of PAIS, is associated with sexual difficulties including vaginal penetration difficulties and dyspareunia.
At least one study indicates that individuals with an intersex condition may be more prone to psychological difficulties, due at least in part to parental attitudes and behaviors, and concludes that preventative long-term psychological counseling for parents as well as for affected individuals should be initiated at the time of diagnosis.
Lifespan is not thought to be affected by AIS.
As babies and children, XXY males may have weaker muscles and reduced strength. As they grow older, they tend to become taller than average. They may have less muscle control and coordination than other boys of their age.
During puberty, the physical traits of the syndrome become more evident; because these boys do not produce as much testosterone as other boys, they have a less muscular body, less facial and body hair, and broader hips. As teens, XXY males may develop breast tissue and also have weaker bones, and a lower energy level than other males.
By adulthood, XXY males look similar to males without the condition, although they are often taller. In adults, possible characteristics vary widely and include little to no sign of affectedness, a , youthful build and facial appearance, or a rounded body type with some degree of gynecomastia (increased breast tissue). Gynecomastia is present to some extent in about a third of affected individuals, a slightly higher percentage than in the XY population. About 10% of XXY males have gynecomastia noticeable enough that they may choose to have cosmetic surgery.
Affected males are often infertile, or may have reduced fertility. Advanced reproductive assistance is sometimes possible.
The term "hypogonadism" in XXY symptoms is often misinterpreted to mean "small testicles" when it means decreased testicular hormone/endocrine function. Because of this (primary) hypogonadism, individuals will often have a low serum testosterone level but high serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels. Despite this misunderstanding of the term, however, it is true that XXY men may also have microorchidism (i.e., small testicles).
The testicle size of affected males are usually less than 2 cm in length (and always shorter than 3.5 cm), 1 cm in width and 4 ml in volume.
XXY males are also more likely than other men to have certain health problems that typically affect females, such as autoimmune disorders, breast cancer, venous thromboembolic disease, and osteoporosis. In contrast to these potentially increased risks, it is currently thought that rare X-linked recessive conditions occur less frequently in XXY males than in normal XY males, since these conditions are transmitted by genes on the X chromosome, and people with two X chromosomes are typically only carriers rather than affected by these X-linked recessive conditions.
Some degree of language learning or reading impairment may be present, and neuropsychological testing often reveals deficits in executive functions, although these deficits can often be overcome through early intervention. There may also be delays in motor development which can be addressed through occupational therapy and physical therapy. XXY males may sit up, crawl, and walk later than other infants; they may also struggle in school, both academically and with sports.
Spermatogenesis arrest is a complex process of interruption in the differentiation of germinal cells of specific cellular type, which elicits an altered spermatozoa formation. Spermatogenic arrest is usually due to genetic factors resulting in irreversible azoospermia. However some cases may be consecutive to hormonal, thermic, or toxic factors and may be reversible either spontaneously or after a specific treatment.
The testicle or testis is the male reproductive gland in all animals, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testosterone. Testosterone release is controlled by the anterior pituitary luteinizing hormone; whereas sperm production is controlled both by the anterior pituitary follicle-stimulating hormone and gonadal testosterone.
Many men who were born with undescended testes have reduced fertility, even after orchiopexy in infancy. The reduction with unilateral cryptorchidism is subtle, with a reported infertility rate of about 10%, compared with about 6% reported by the same study for the general population of adult men.
The fertility reduction after orchiopexy for bilateral cryptorchidism is more marked, about 38%, or 6 times that of the general population. The basis for the universal recommendation for early surgery is research showing degeneration of spermatogenic tissue and reduced spermatogonia counts after the second year of life in undescended testes. The degree to which this is prevented or improved by early orchiopexy is still uncertain.
There is a small body of research on the psychology of cryptorchidism, that attempts to determine whether this condition can cause lasting psychological problems. The psychological research on cryptorchism consists of only a few case reports and small studies. This research also has serious methodological problems: major variables are completely uncontrolled, such as the small physical stature of many cryptorchid boys, and the psychological effects of corrective surgery.
Existing research indicates that boys with undescended testicles do not tend to be gender-disordered, effeminate, or pre-homosexual. A disturbed self-image forms only when the family dynamics are destructive to developing male self-esteem. Such pathogenic attitudes were found in parents who focused on the boy’s genital defect as a sign of his presumed effeminacy. However, when the cryptorchism is surgically corrected a healthy masculinity becomes possible. The basic sexual normality of these boys was confirmed in a small retrospective study that tested adolescent boys several years after their condition was surgically repaired. They had developed into fairly well-adjusted teenagers without special sexual or gender problems, and with no distinctive traits of psychopathological relevance.
Testicular enlargement is an unspecific sign of various testicular diseases, and can be defined as a testicular size of more than 5 cm (long axis) x 3 cm (short axis).
Blue balls is a slang term for a temporary fluid congestion in the testicles and prostate region caused by prolonged sexual arousal.
Testicular prostheses are available to mimic the appearance and feel of one or both testicles, when absent as from injury or as treatment in association to gender dysphoria. There have also been some instances of their implantation in dogs.
Symptoms for Alström syndrome generally appear during infancy with great variability in age. Some of the symptoms include:
- Heart failure (Dilated cardiomyopathy) in over 60% of cases, usually within the first few weeks after birth, but sometimes the onset is in adolescence or adulthood.
- Light sensitivity and vision problems (Cone-rod dystrophy) in all cases, usually within 15 months of birth and progressively worsening until about 20 years of age
- Delays in early, developmental milestones in 50% of cases, learning disabilities in about 30% of cases
- Obesity in 100% of cases, apparent by 5 years of age, but often apparent in infancy (Alström infants usually have normal birth weights, and by adolescence, weights tend to be in the high-normal to normal range)
- Nystagmus (usually affects the children) one of the first symptoms to occur which causes involuntary rapid eye movement.
- Heart failure (Dilated cardiomyopathy) in over 60% of cases, usually within the first few weeks after birth, but sometimes the onset is in adolescence or adulthood.(chronic)
- Mild to moderate bilateral sensorineural hearing loss.
- Type 2 diabetes usually occurs in early childhood.
- Hyperinsulinemia/ insulin resistance—development of high level of insulin in blood.
- Steatosis (fatty liver) and elevated transaminases (liver enzymes) often develop in childhood and can progress in some patients to cirrhosis and liver failure.
- Endocrine dysfunctions may occur where the patient may experience an under or over active thyroid gland, weak growth hormone, increased androgen in females, and low testosterone in males.
- Slowly progressive kidney failure can occur in the second to fourth decade of life.
Tricho-hepato-enteric syndrome is one particular form of intractable diarrhea of infancy, presenting typically in the first month of life. These babies were usually born small for their age and continue to experience failure to thrive, usually with a final short stature. Typical facial features include prominent forehead and cheeks, a broad nasal root and widely spaced eyes (hypertelorism). Their hairs are woolly, easily removed and poorly pigmented. Liver disease is mainly present as cirrhosis or fibrosis, and staining might reveal high iron content of the liver cells (consistent with hemochromatosis). Most evaluated patients had some degree of decrease in intelligence.
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.
The main consequence of impaired ciliary function is reduced or absent mucus clearance from the lungs, and susceptibility to chronic recurrent respiratory infections, including sinusitis, bronchitis, pneumonia, and otitis media. Progressive damage to the respiratory system is common, including progressive bronchiectasis beginning in early childhood, and sinus disease (sometimes becoming severe in adults). However, diagnosis is often missed early in life despite the characteristic signs and symptoms. In males, immotility of sperm can lead to infertility, although conception remains possible through the use of in vitro fertilization and, as well as this, there have been reported cases where sperm were able to move. Trials have also shown that there is a marked reduction in fertility in female sufferers of Kartagener's Syndrome due to dysfunction of the oviductal cilia.
Many affected individuals experience hearing loss and show symptoms of otitis media which demonstrate variable responsiveness to the insertion of myringotomy tubes or grommets. Some patients have a poor sense of smell, which is believed to accompany high mucus production in the sinuses (although others report normal - or even acute - sensitivity to smell and taste). Clinical progression of the disease is variable, with lung transplantation required in severe cases. Susceptibility to infections can be drastically reduced by an early diagnosis. Treatment with various chest physiotherapy techniques has been observed to reduce the incidence of lung infection and to slow the progression of bronchiectasis dramatically. Aggressive treatment of sinus disease beginning at an early age is believed to slow long-term sinus damage (although this has not yet been adequately documented). Aggressive measures to enhance clearance of mucus, prevent respiratory infections, and treat bacterial superinfections have been observed to slow lung-disease progression. Although the true incidence of the disease is unknown, it is estimated to be 1 in 32,000,
although the actual incidence may be as high as 1 in 15,000.
Jalili syndrome is a genetic disorder characterized by the combination of cone-rod dystrophy of the retina and amelogenesis imperfecta. It was characterized in 1988 by Dr. I. K. Jalili and Dr. N. J. D. Smith, following the examination of 29 members of an inbred, Arab family living within the Gaza Strip.
Alström syndrome, also called Alstrom-Halgren syndrome, is a rare genetic disorder caused by mutations in the gene ALMS1. It is among the rarest genetic disorders in the world, as currently it has only 266 reported cases in medical literature and over 501 known cases in 47 countries. It was first described by Carl-Henry Alström in Sweden in 1959. Alstrom syndrome is sometimes confused with Bardet-Biedl syndrome, which has similar symptoms. Bardet-Biedl syndrome tends to have later onset in its symptoms. The likelihood of two carrier parents both passing the gene and therefore having a child affected by the syndrome is 25% with each pregnancy. The likelihood of having a child who is only a carrier of the gene is 50% with each pregnancy. The likelihood of a child receiving normal genes from both parents and being considered to be "genetically" normal is 25%. The risk for carrying the gene is equivalent for both males and females.
"Alström syndrome (AS) is a rare autosomal recessive disease characterized by multiorgan dysfunction. The key features are childhood obesity, blindness due to congenital retinal dystrophy, and sensorineural hearing loss. Associated endocrinologic features include hyperinsulinemia, early-onset type 2 diabetes, and hypertriglyceridemia."
Thus, AS shares several features with the common metabolic syndrome, namely obesity, hyperinsulinemia, and hypertriglyceridemia. Mutations in the ALMS1 gene have been found to be causative for AS with a total of 79 disease-causing mutations having been described." Prevalence estimates have ranged from 1 in 10,000 to fewer than 1 in 1,000,000 individuals in the general population.
Tricho-hepato-enteric syndrome (THE), also known as syndromic or phenotypic diarrhea, is an extremely rare congenital bowel disorder which manifests itself as intractable diarrhea in infants with intrauterine growth retardation, hair and facial abnormalities. Many also have liver disease and abnormalities of the immune system. The associated malabsorption leads to malnutrition and failure to thrive.
It is thought to be a genetic disorder with an autosomal recessive inheritance pattern, although responsible genes have not been found and the exact cause remains unknown. Prognosis is poor; many patients die before the age of 5 (mainly from infections or cirrhosis), although most patients nowadays survive with intravenous feeding (parenteral nutrition).
CCD causes persistent secretory diarrhea. In a fetus, it leads to polyhydramnios and premature birth. Immediately after birth, it leads to dehydration, hypoelectrolytemia, hyperbilirubinemia, abdominal distention, and failure to thrive.
Primary ciliary dyskinesia (PCD), also called immotile ciliary syndrome or Kartagener syndrome, is a rare, ciliopathic, autosomal recessive genetic disorder that causes defects in the action of cilia lining the respiratory tract (lower and upper, sinuses, Eustachian tube, middle ear), fallopian tube, and flagella of sperm cells. The phrase "immotile ciliary syndrome" is no longer favored as the cilia do have movement, but are merely inefficient or unsynchronized.
Respiratory epithelial motile cilia, which resemble microscopic "hairs" (although structurally and biologically unrelated to hair), are complex organelles that beat synchronously in the respiratory tract, moving mucus toward the throat. Normally, cilia beat 7 to 22 times per second, and any impairment can result in poor mucociliary clearance, with subsequent upper and lower respiratory infection. Cilia also are involved in other biological processes (such as nitric oxide production), which are currently the subject of dozens of research efforts. As the functions of cilia become better understood, the understanding of PCD should be expected to advance.
Sirenomelia, alternatively known as Mermaid syndrome, is a rare congenital deformity in which the legs are fused together, giving them the appearance of a mermaid's tail as the nickname suggests.
This condition is found in approximately one out of every 100,000 live births (about as rare as conjoined twins) and is usually fatal within a day or two of birth because of complications associated with abnormal kidney and urinary bladder development and function. More than half the cases of sirenomelia result in stillbirth and this condition is 100 times more likely to occur in identical twins than in single births or fraternal twins. It results from a failure of normal vascular supply from the lower aorta in utero. Maternal diabetes has been associated with caudal regression syndrome and sirenomelia, although a few sources question this association.
VACTERL-H is an expanded form of the VACTERL association that concludes that this diagnosis is a less severe form of sirenomelia. The disorder was formerly thought to be an extreme case of caudal regression syndrome; however, it was reclassified to be considered a separate condition.
Gerodermia osteodysplastica is characterized by symptoms and features which affect the connective tissues, skin and skeletal system.
These are: wrinkly, loose skin over the face, abdomen, and extremites (hands, feet) on the dorsal sides usually worsened by chronic joint laxity and hyperextensibility; fragmented elastic fibers of the skin that are reduced in number, with disorientation of collagen fibers; osteopenia and osteoporosis, with associated fractures; malar hypoplasia (underdeveloped cheek bone), maxillary hypoplasia (underdeveloped upper jaw), mandibular prognathism (protrusion of the lower jaw and chin), bowed long bones, platyspondyly (flattened spine) related to vertebral collapse; kyphoscoliosis (scoliosis with kyphosis, or "hunch back"), metaphyseal peg (an unusual outgrowth of metaphyseal tissue which protrudes into the epiphyseal region of the bone, near the knee); and the overall physical effects and facial appearance of dwarfism with premature aging.
Other features and findings include: intrauterine growth retardation, congenital hip dislocations, winged scapulae (shoulder blades), pes planus (fallen arches), pseudoepiphyses of the second metacarpals (upper bone of the fingers), hypotelorism (close-set eyes), malformed ears,
developmental delay,
failure to thrive and abnormal electroencephalograph (EEG) readings.
Dental and orthodontal abnormalities in addition to maxillary hypoplasia and mandibular prognathism have also been observed in gerodermia osteodysplastica. Including malocclusion of the dental arches (the maxilla and mandible), radiological findings in some cases have indicated significant overgrowth of the mandibular premolar and molar roots;
hypercementosis (overproduction of cementum) of the molars and maxillary incisors; enlarged, funnel-shaped mandibular lingula (spiny structures on the ramus of the mandible); and a radiolucent effect on portions of many teeth, increasing their transparency to x-rays.
Gerodermia osteodysplastica (GO), also called geroderma osteodysplasticum and Walt Disney dwarfism, is a rare autosomal recessive connective tissue disorder included in the spectrum of cutis laxa syndromes.
Usage of the name "Walt Disney dwarfism" is attributed to the first known case of the disorder, documented in a 1950 journal report, in which the authors described five affected members from a Swiss family as having the physical appearance of dwarves from a Walt Disney film.
The terms "geroderma" or "gerodermia" can be used interchangeably with "osteodysplastica" or "osteodysplasticum", with the term "hereditaria" sometimes appearing at the end.
Congenital chloride diarrhea (CCD, also congenital chloridorrhea or Darrow Gamble syndrome) is a genetic disorder due to an autosomal recessive mutation on chromosome 7. The mutation is in downregulated-in-adenoma (DRA), a gene that encodes a membrane protein of intestinal cells. The protein belongs to the solute carrier 26 family of membrane transport proteins. More than 20 mutations in the gene are known to date. A rare disease, CCD occurs in all parts of the world but is more common in some populations with genetic founder effects, most notably in Finland.
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.