Editing Potter sequence (section)

==Signs and symptoms==
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 [[Urinary bladder|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 (medical)|facies]].  Lower extremity anomalies are frequent in these cases, which often present with clubbed feet and/or bowing of the legs. [[Sirenomelia]], or "Mermaid syndrome" (which occurs approximately in 1:45,000 births)<ref>Banerjee A, 2003; Indian J Pediatr</ref> can also present. In fact, nearly all reported cases of [[sirenomelia]] also present with BRA.It is associated with childhood polycystic kidney disease which is autosomal recessive in origin <ref name=Herman-Siegel>{{cite journal|last=Herman|first=TE|author2=Siegel, MJ|title=Special imaging casebook. Oligohydramnios sequence with bilateral renal agenesis (Potter's syndrome)|journal=Journal of Perinatology|date=September 2000|volume=20|issue=6|pages=397–8|pmid=11002883|doi=10.1038/sj.jp.7200222|doi-access=free}}</ref>

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 (anatomy)|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 [[anus|anal]] atresia, absence of the [[rectum]] and [[sigmoid colon]], [[Esophageal atresia|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.{{citation needed|date=April 2021}}