What are the other Names for this Condition? (Also known as/Synonyms)

• Oligomeganephronia

What is Oligomeganephronic Renal Hypoplasia? (Definition/Background Information)

• Oligomeganephronic Renal Hypoplasia, or Oligomeganephronia is a developmental anomaly of the kidneys, and the most severe form of renal hypoplasia, characterized by a reduction of 80% in nephron number and a marked hypertrophy of the glomeruli and tubules
• Oligomeganephronia is usually detected on routine ultrasound screening with small but normal shaped kidneys
• Birth weight is often below the average value. Patients may present at birth with polyuria/polydipsia or signs of renal dysfunction such as anemia
• During the first year of life, the usual symptom is persistent anorexia with vomiting, fever, and height-weight growth delay. Renal failure typically occurs during childhood or adolescence. Adult-onset Oligomeganephronia has been reported in some rare cases
• Most cases are sporadic, but familial occurrence has been described

(Source: Oligomeganephronic Renal Hypoplasia; Orphanet, National Institute of Health and Medical Research (INSERM), Paris.)

Who gets Oligomeganephronic Renal Hypoplasia? (Age and Sex Distribution)

• Oligomeganephronic Renal Hypoplasia is a rare disorder affecting the kidneys. The prevalence of this condition is not known
• The onset of symptoms may occur at birth; although, onset in adulthood is also reported
• Both genders may be affected by this disorder. However, the condition is three timesmore prevalent in males, when compared to females

What are the Risk Factors for Oligomeganephronic Renal Hypoplasia? (Predisposing Factors)

The risk factors for Oligomeganephronic Renal Hypoplasia may include the following:

• A positive family history may be an important risk factor, since the condition can be inherited in some cases
• Maternal diabetes during pregnancy
• Maternal drug use
• Intra-uterine growth restriction
• Premature birth

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Oligomeganephronic Renal Hypoplasia? (Etiology)

• The exact cause of Oligomeganephronic Renal Hypoplasia is not known at the present time. However, it is theorized that the condition may be caused by a premature arrest of the development of kidney tissues (nephrogenesis)
• This cessation of nephrogenesis may be caused by:
  • Maternal diseases during pregnancy, including diabetes and high blood pressure
  • Use of certain drugs by the mother during pregnancy, such as inhibitors of the renin-angiotensin system and non-steroidal anti-inflammatory drugs (NSAIDs)
  • Smoking and drinking of alcohol by the mother during pregnancy
  • Intra-uterine growth restriction due to various factors
  • Premature birth of the baby, before 36 weeks of gestation are completed
• Most cases of Oligomeganephronic Renal Hypoplasia are sporadic. However, the disorder can occur as part of a multi-organ syndrome such as:
  • Renal coloboma syndrome, caused by mutations in the PAX2 gene
  • 22q11 deletion syndrome
  • Wolf-Hirschhorn syndrome

What are the Signs and Symptoms of Oligomeganephronic Renal Hypoplasia?

The signs and symptoms of Oligomeganephronic Renal Hypoplasia may include:

• Low birth weight
• Polyuria
• Polydipsia
• Anemia
• Persistent anorexia with vomiting
• Fever 
• Height-weight growth delay

How is Oligomeganephronic Renal Hypoplasia Diagnosed?

Oligomeganephronic Renal Hypoplasia is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies, which may show bilateral, normal-shaped, small kidneys
• Biopsy of kidney tissue, which may show reduced number of nephrons in histological studies

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Oligomeganephronic Renal Hypoplasia?

The complications of Oligomeganephronic Renal Hypoplasia may include:

• Extreme weakness due to anemia
• Chronic kidney failure
• End-stage renal disease

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Oligomeganephronic Renal Hypoplasia Treated?

The goal of treatment for Oligomeganephronic Renal Hypoplasia is to slow the progression of disease. Treatment methods may involve

• Medications such as angiotensin-converting-enzyme (ACE) inhibitors 
• Dialysis
• Kidney transplantation

How can Oligomeganephronic Renal Hypoplasia be Prevented?

Currently, Oligomeganephronic Renal Hypoplasia may not be preventable, if it is an inherited disorder

• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Most reported cases of Oligomeganephronic Renal Hypoplasia are sporadic, and no guidelines or methods are available to prevent the condition at this time
• Maintenance of optimal blood pressure, good glycemic index and abstinence from smoking and drinking by the mother during pregnancy may help reduce the risk of Oligomeganephronic Renal Hypoplasia in the newborn
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended

What is the Prognosis of Oligomeganephronic Renal Hypoplasia? (Outcomes/Resolutions)

• The prognosis of Oligomeganephronic Renal Hypoplasia is dependent upon the severity of the signs and symptoms and associated complications, if any
• The condition is progressive. In most cases, an increasing demand on the kidneys during rapid growth causes kidney malfunction and ultimately kidney failure, before an affected individual reaches the age of 20 years

Additional and Relevant Useful Information for Oligomeganephronic Renal Hypoplasia:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/