Potter syndrome or sequence: types, symptoms and causes

Different factors, among which malformations in the kidneys stand out, can interfere with intrauterine development and cause alterations in other body systems.

In this article we will talk about the causes, symptoms and types of Potter syndrome, name by which this phenomenon is known, often of genetic origin.

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What is the Potter sequence?

The terms "Potter sequence" and "Potter syndrome" are used to refer to a set of physical malformations that occur in babies as a result of alterations in the kidneys, the absence of amniotic fluid (oligohydramnios) or compression during development intrauterine.

In 1946 the doctor Edith Potter described twenty cases of people without kidneys who also presented peculiar physical features in the head and lungs. Potter's contributions were key to raising awareness about this disease, more frequent than previously believed.

Potter believed that this type of physical malformation was always due to the absence of the kidneys, or renal agenesis; however, other possible causes were later found to exist. The typological classification that we currently use was developed around these and the associated alterations.

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Causes of this alteration

Potter syndrome often is associated with diseases and problems of the urinary system such as agenesis of the kidneys and ureter, polycystic kidney disease and multicystic kidney disease, or urinary tract obstruction, which can be due to both genetic and environmental causes.

Many cases of Potter syndrome have a genetic origin (although not always hereditary); Mutations on chromosomes 1, 2, 5, and 21 have been identified in the variants with bilateral renal agenesis, and similar causes have also been identified in the other types.

The development of the classical variant consists of a series of interrelated events; this is why it is also called the "Potter sequence". Incomplete formation of the kidneys and / or ureter or rupture of the amniotic sac they cause the fetus not to have enough amniotic fluid to form properly.

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Symptoms and main signs

Sometimes the signs that characterize Potter syndrome can be seen already during intrauterine development. Most commonly, medical tests reveal the presence of cysts in the kidneys or oligohydramnios or absence of amniotic fluid, which is usually due to the rupture of the sac that contains it.

After birth, the facial features described by Potter become evident: a flattened nose, epicanthic folds in the eyes, a retracted chin, and abnormally lowered ears. In addition, alterations can occur in the lower and upper extremities. However, these characteristics are not always present to the same degree.

Potter syndrome is also associated with malformations in the eyes, in the lungs, in the cardiovascular system, in the intestines and bones, especially in the vertebrae. The urogenital system is usually very significantly altered.

Types of Potter syndrome

At present the different forms that Potter syndrome takes are classified into five large categories or types. These differ both in causes and in nuclear clinical manifestations. On the other hand, it is important to also mention the classic form of this disease and that associated with multicystic renal dysplasia, discovered very recently.

1. Type I

This variant of Potter syndrome occurs as consequence of autosomal recessive polycystic kidney disease, an inherited disease that affects the kidneys and is characterized by the appearance of numerous small, fluid-filled cysts. This causes the kidneys to enlarge and interferes with urine production.

2. Type II

The main feature of type II is renal agenesis or aplasia, that is, the congenital absence of one or both kidneys; in the second case we speak of bilateral renal agenesis. Since other parts of the urinary system, such as the ureter, are also often affected, these signs are often referred to as "urogenital agenesis." The origin is usually hereditary.

3. Type III

In this case, the malformations are due to autosomal dominant polycystic kidney disease (unlike type I, in which the disease is transmitted by recessive inheritance). Cysts are observed in the kidneys and an enlargement of their size, as well as an increase in the frequency of vascular diseases. Symptoms usually manifest in adult life.

4. Type IV

Potter's syndrome type IV is diagnosed when cysts appear and / or water accumulates (hydronephrosis) in the kidneys due to a chronic obstruction of this organ or the ureter. It is a common variant during the fetal period that does not usually cause spontaneous abortion. The cause of these alterations can be both genetic and environmental.

5. Classic shape

When we talk about the classic Potter syndrome, we are referring to cases in which the kidneys do not develop (bilateral renal agenesis), and neither does the ureter. It has been proposed that the classic form described by Potter in 1946 can be considered an extreme version of type II, also characterized by renal agenesis.

6. Multicystic renal dysplasia

Multicystic renal dysplasia is a disorder characterized by the presence of numerous and irregular cysts in the kidneys; Compared to the term "polycystic", "multicystic" indicates less severity. In recent years, cases of Potter syndrome due to this disorder have been identified that could indicate a possible new type.