Renal agenesis | |
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Specialty | Nephrology |
Renal agenesis is a medical condition in which one (unilateral) or both (bilateral) fetal kidneys fail to develop.
Unilateral and bilateral renal agenesis in humans, mice and zebra fish has been linked to mutations in the gene GREB1L. [1] It has also been associated with mutations in the genes RET or UPK3A [2] in humans [3] and mice respectively.
Bilateral renal agenesis (BRA) is a condition in which both kidneys of a fetus fail to develop during gestation. It is incompatible with life. [4] It is one causative agent of Potter sequence. This absence of kidneys causes oligohydramnios, a deficiency of amniotic fluid in a pregnancy, which can place extra pressure on the developing baby and cause further malformations. The condition is frequently, but not always the result of a genetic disorder, and is more common in infants born to one or more parents with a malformed or absent kidney.[ citation needed ]
This is much more common, but is not usually of any major health consequence, as long as the single kidney is healthy. However, this kidney tends to be hypertrophied, ectopic and prone to infection and damage. [4]
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 unilateral renal agenesis is combined with a blind hemivagina and uterus didelphys. [5] Up to 40% of women with a urogenital tract anomaly also have an associated renal tract anomaly. [6]
Adults with unilateral renal agenesis have considerably higher chances of hypertension (high blood pressure). People with this condition are advised [7] to approach contact sports with caution.
A possible complication later in life of unilateral renal agenesis is focal segmental glomerular sclerosis (FSGS) which will cause nephrotic syndrome, potentially resulting from glomerular overload. [8]
In 2008 researchers found autosomal dominant mutations in the RET and GDNF genes to be linked to renal agenesis in unrelated stillborn fetuses through PCR and direct sequence analysis. [9] In the study, DNA from 33 stillborn fetuses were sequenced for mutations in RET, GDNF and GFRA1. Nineteen of the fetuses had BRA, ten had URA and 4 had congenital renal dysplasia. Seven of the 19 BRA fetuses were found to have a mutation in the RET gene (37%), while two of the ten URA fetuses did (20%). One of the URA fetuses had two RET mutations and one GDNF mutation. There were no GFRA1 mutations found.[ citation needed ]
However, the results of Skinner et al. study were questioned by a more recent study with a larger number of cases. [10] In this study 105 fetuses were analyzed. Sixty-five fetuses had BRA while 24 had URA with an abnormal contralateral kidney. Mutations in the RET gene were only found in seven of the fetuses (6.6%).[ citation needed ]
In 2014 researchers found autosomal recessive mutations in ITGA8 in three members of two unrelated families utilizing exome sequencing. One of the families was consanguineous.[ citation needed ]
In 2017 researchers identified heritable autosomal dominant mutations in the gene GREB1L in two unrelated families as being the cause of both BRA and URA utilizing Exome Sequencing and direct sequencing analysis. [1] This is the first reported genetic lesion implicated in the activation of Retinoic Acid Receptor (RAR) Targets that has been associated with renal agenesis in humans. The researchers found two different GREB1L mutations, each being unique to their respective pedigrees. In total, there were 23 individuals analyzed between the two families, four of which had BRA and five of which had URA. GREB1L mutations were identified in all of the affected individuals as well as in three unaffected family members, demonstrating incomplete penetrance and variable expressivity.[ citation needed ]
There are several hundred to perhaps several thousand genes that, if they had the right kind of mutation, could lead to renal agenesis in humans. It is possible that each individual or family experiencing renal agenesis has a unique gene or genetic mutation causing the condition due to the fact that there are so many genes that are critical to proper renal development. [3]
Chromosomal anomalies have been associated with BRA in certain cases (chromosomes 1, 2, 5 and 21), but these anomalies were not inherited and have not been observed in subsequent cases. Additionally, neither extreme substance abuse or environmental factors (high power line, mercury, ground water issues, etc.) have been reported to be linked to an increased incidence of BRA or other cause of Potter sequence. However, renal agenesis and other causes of oligohydramnios sequence have been linked to a number of other conditions and syndromes to include Down syndrome, Kallmann syndrome, branchio-oto-renal syndrome and others.[ citation needed ]
The prevalence of unilateral renal agenesis in the population is approximately 1 in about 1000 people. Bilateral agenesis occurs in 1 in about 2500 foetuses. [4]
Joubert syndrome is a rare autosomal recessive genetic disorder that affects the cerebellum, an area of the brain that controls balance and coordination.
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.
Atresia is a condition in which an orifice or passage in the body is closed or absent.
Fraser syndrome is an autosomal recessive congenital disorder, identified by several developmental anomalies. Fraser syndrome is named for the geneticist George R. Fraser, who first described the syndrome in 1962.
Barakat syndrome is a rare disease characterized by hypoparathyroidism, sensorineural deafness and renal disease, and hence also known as HDR syndrome. It is an autosomal dominant condition with incomplete penetrance and variable expressivity that was first described by Amin J. Barakat et al. in 1977.
Congenital absence of the vas deferens (CAVD) is a condition in which the vasa deferentia reproductive organs fail to form properly prior to birth. It may either be unilateral (CUAVD) or bilateral (CBAVD).
Robinow syndrome is an extremely rare genetic disorder characterized by short-limbed dwarfism, abnormalities in the head, face, and external genitalia, as well as vertebral segmentation. The disorder was first described in 1969 by human geneticist Meinhard Robinow, along with physicians Frederic N. Silverman and Hugo D. Smith, in the American Journal of Diseases of Children. By 2002, over 100 cases had been documented and introduced into medical literature.
Duane-radial ray syndrome, also known as Okihiro syndrome, is a rare autosomal dominant disorder that primarily affects the eyes and causes abnormalities of bones in the arms and hands. This disorder is considered to be a SALL4-related disorder due to the SALL4 gene mutations leading to these abnormalities. It is diagnosed by clinical findings on a physical exam as well as genetic testing and imaging. After being diagnosed, there are other evaluations that one may go through in order to determine the extent of the disease. There are various treatments for the symptoms of this disorder.
Papillorenal syndrome is an autosomal dominant genetic disorder marked by underdevelopment (hypoplasia) of the kidney and colobomas of the optic nerve.
Branchio-oto-renal syndrome (BOR) is an autosomal dominant genetic disorder involving the kidneys, ears, and neck. It is also known as Melnick-Fraser syndrome.
Vici syndrome, also called immunodeficiency with cleft lip/palate, cataract, hypopigmentation and absent corpus callosum, is a rare autosomal recessive congenital disorder characterized by albinism, agenesis of the corpus callosum, cataracts, cardiomyopathy, severe psychomotor retardation, seizures, immunodeficiency and recurrent severe infections. To date, about 50 cases have been reported.
Multicystic dysplastic kidney (MCDK) is a condition that results from the malformation of the kidney during fetal development. The kidney consists of irregular cysts of varying sizes. Multicystic dysplastic kidney is a common type of renal cystic disease, and it is a cause of an abdominal mass in infants.
Autosomal recessive polycystic kidney disease (ARPKD) is the recessive form of polycystic kidney disease. It is associated with a group of congenital fibrocystic syndromes. Mutations in the PKHD1 cause ARPKD.
Malpuech facial clefting syndrome, also called Malpuech syndrome or Gypsy type facial clefting syndrome, is a rare congenital syndrome. It is characterized by facial clefting, a caudal appendage, growth deficiency, intellectual and developmental disability, and abnormalities of the renal system (kidneys) and the male genitalia. Abnormalities of the heart, and other skeletal malformations may also be present. The syndrome was initially described by Georges Malpuech and associates in 1983. It is thought to be genetically related to Juberg-Hayward syndrome. Malpuech syndrome has also been considered as part of a spectrum of congenital genetic disorders associated with similar facial, urogenital and skeletal anomalies. Termed "3MC syndrome", this proposed spectrum includes Malpuech, Michels and Mingarelli-Carnevale (OSA) syndromes. Mutations in the COLLEC11 and MASP1 genes are believed to be a cause of these syndromes. The incidence of Malpuech syndrome is unknown. The pattern of inheritance is autosomal recessive, which means a defective (mutated) gene associated with the syndrome is located on an autosome, and the syndrome occurs when two copies of this defective gene are inherited.
Genitopatellar syndrome is a rare disorder consisting of congenital flexion contractures of the lower extremities, abnormal or missing patellae, and urogenital anomalies. Additional symptoms include microcephaly, severe psychomotor disability. In 2012, it was shown that mutations in the gene KAT6B cause the syndrome. Genitopatellar syndrome (GTPTS) can be caused by heterozygous mutation in the KAT6B gene on chromosome 10q22. The Say-Barber-Biesecker variant of Ohdo syndrome, which has many overlapping features with GTPTS, can also be caused by heterozygous mutation in the KAT6B gene.
Müllerian duct anomalies are those structural anomalies caused by errors in Müllerian duct development as an embryo forms. Factors contributing to them include genetics and maternal exposure to substances that interfere with fetal development.
Vaginal anomalies are abnormal structures that are formed during the prenatal development of the female reproductive system and are rare congenital defects that result in an abnormal or absent vagina.
Renal hypoplasia is a congenital abnormality in which one or both of the kidneys are smaller than normal, resulting in a reduced nephron number but with normal morphology.
17q12 microdeletion syndrome, also known as 17q12 deletion syndrome, is a rare chromosomal anomaly caused by the deletion of a small amount of material from a region in the long arm of chromosome 17. It is typified by deletion of the HNF1B gene, resulting in kidney abnormalities and renal cysts and diabetes syndrome. It also has neurocognitive effects, and has been implicated as a genetic factor for autism and schizophrenia.
Chudley–Mccullough syndrome is a rare genetic disorder which is characterized by bilateral congenital hearing loss associated with brain malformations. It is a type of syndromic deafness.