Multicystic dysplastic kidney (MCDK) is a condition that results from the malformation of the

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...

during

fetal development Prenatal development () includes the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal devel ...

. The kidney consists of irregular cysts of varying sizes. Multicystic dysplastic kidney is a common type of renal

cystic A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble) ...

disease, and it is a cause of an

abdominal mass An abdominal mass is any localized enlargement or swelling in the human abdomen. Depending on its location, the abdominal mass may be caused by an enlarged liver (hepatomegaly), enlarged spleen (splenomegaly), protruding kidney, a pancreatic mass, ...

in infants.

Signs and symptoms

When a diagnosis of multicystic kidney is made in utero by ultrasound, the disease is found to be bilateral in many cases. Those with bilateral disease often have other severe deformities or polysystemic malformation syndromes. In bilateral cases, the newborn has the classic characteristic of Potter's syndrome. The bilateral condition is incompatible with survival, as the contralateral system frequently is abnormal as well. Contralateral

ureteropelvic junction The ureters are tubes made of smooth muscle that propel urine from the kidneys to the urinary bladder. In a human adult, the ureters are usually long and around in diameter. The ureter is lined by urothelial cells, a type of transitional epith ...

obstruction is found in 3% to 12% of infants with multicystic kidney and contralateral

vesicoureteral reflux Vesicoureteral reflux (VUR), also known as vesicoureteric reflux, is a condition in which urine flows retrograde, or backward, from the bladder into one or both ureters and then to the renal calyx or kidneys. Urine normally travels in one directi ...

is seen even more often, in 18% to 43% of infants. Because the high incidence of reflux, voiding cystourethrography usually has been considered advisable in all newborns with a multicystic kidney.

Cause

The cause of multicystic dysplastic kidney can be attributed to

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...

. Renal dysplasia can be a consequence of a genetic syndrome, which in turn may affect the digestive tract, nervous system, or other areas of the

urinary tract The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, con ...

. If the mother had been taking certain prescription drugs such as those for

hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...

, this may be a precipitating factor as well. Ultrasound Scan ND 0119092150 0939241

Pathophysiology

The mechanism of multicystic dysplastic kidney is a result of an abnormal induction of metanephric mesenchyme. This could be a result of a formation difficulty of the

mesonephric duct The mesonephric duct (also known as the Wolffian duct, archinephric duct, Leydig's duct or nephric duct) is a paired Organ (anatomy), organ that forms during the embryonic development of humans and other mammals and gives rise to male Sex organ, r ...

. Some mutations in genes associated with renal dysplasia (in syndromes) have been determined. The mutations in question occur at

EYA1 Eyes absent homolog 1 is a protein that in humans is encoded by the ''EYA1'' gene. This gene encodes a member of the eyes absent (EYA) subfamily of proteins. The encoded protein may play a role in the developing kidney, branchial arches, eye, an ...

SIX1 Homeobox protein SIX1 (Sine oculis homeobox homolog 1) is a protein that in humans is encoded by the ''SIX1'' gene. Function The vertebrate SIX genes are homologs of the Drosophila 'sine oculis' (so) gene, which is expressed primarily in the ...

genes (branchio-oto-renal syndrome). The

PAX2 Paired box gene 2, also known as Pax-2, is a protein which in humans is encoded by the ''PAX2'' gene. Function The Pax Genes, or Paired-Box Containing Genes, play important roles in the development and proliferation of multiple cell lines, dev ...

gene is also thought to play a role in MCDK. The contralateral kidney often undergoes hypertrophy. This is believed to be a compensatory mechanism to the non-functional MCDK. About 90% of patients with an MCDK will have contralateral hypertrophy into adulthood. The impact of contralateral hypertrophy on long-term renal outcomes is unknown.

Diagnosis

MCDK is usually diagnosed by

ultrasound Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...

examination before birth. Mean age at the time of antenatal diagnosis is about 28 weeks A

microscopic The microscopic scale () is the scale of objects and events smaller than those that can easily be seen by the naked eye, requiring a lens (optics), lens or microscope to see them clearly. In physics, the microscopic scale is sometimes regarded a ...

analysis of urine in individuals with probable multicystic dysplastic kidney should be done. One meta-analysis demonstrated that unilateral MCDK occurs more frequently in males and the greater percentage of MCKD occur on the left side of the body.

Treatment

MCDK is not treatable. However, the patient is observed periodically for the first few years during which

ultrasounds Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies fr ...

are generally taken to ensure the healthy kidney is functioning properly and that the unhealthy kidney is not causing adverse effects. In severe cases MCDK can lead to neonatal fatality (in

bilateral Bilateral may refer to any concept including two sides, in particular: * Bilateria, bilateral animals *Bilateralism, the political and cultural relations between two states *Bilateral, occurring on both sides of an organism ( Anatomical terms of ...

cases), however in

unilateral __NOTOC__ Unilateralism is any doctrine or agenda that supports one-sided action. Such action may be in disregard for other parties, or as an expression of a commitment toward a direction which other parties may find disagreeable. As a word, ''un ...

cases the prognosis might be better (it would be dependent on associated anomalies).

Epidemiology

In regard to the epidemiology of multicystic dysplasia kidney, the incidence of MCDK is estimated to be 1 in every 4,000 live births, making it rare in terms of the general population.

References

External links

{{Medicine Congenital disorders of urinary system Kidney diseases