What is renal cysts and diabetes syndrome?

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RCAD describes a rare type of diabetes that also results in the formation of cysts in the kidneys. It occurs due to a gene change that affects not only insulin production but also kidney development.

Health experts may also refer to RCAD as MODY 5 or HNF1B MODY. This is because it refers to a rare group of diabetes called MODY, in which genetic variations limit the body’s ability to produce insulin. As the name implies, MODY usually affects children, adolescents, and young adults, often manifesting before the age of 25 years.

The prevalence of MODY is roughly 1 in 23,000 children, and it may account for about 5% of all diabetes cases in the United States. However, experts believe that doctors mistakenly diagnose 90% of people with MODY with another type of diabetes. Evidence suggests that MODY 5 is one of the more common subtypes, accounting for 5–10% of MODY cases.

Health experts may refer to all types of MODY as monogenic diabetes. This is because these conditions are the result of an alteration in a single gene. MODY follows an autosomal dominant inheritance pattern, meaning that only one copy of an altered gene is necessary to develop the condition.

Typically, MODY occurs due to inheriting an altered gene from a parent. If a person inherits this genetic change, they will usually develop MODY before the age of 25 years, regardless of their weight, lifestyle, and racial and ethnic background. However, MODY 5 can arise from new mutations in a gene and occur in people with no family history of MODY.

In people with RCAD, the condition develops due to a mutation in the hepatic nuclear factor 1B gene, also known as the HNF1B gene. This gene is responsible for producing proteins that act as transcription factors, helping control the activity of other genes. In particular, HNF1B helps regulate genes that play a role in the development of beta cells and the kidneys.

Beta cells are a type of special cell present in the pancreas that secretes insulin. Due to the genetic change, the HNF1B gene produces an altered transcription factor that is unable to function correctly. This results in the beta cells being less able to produce sufficient levels of insulin to help control blood sugar levels.

The HNF1B gene also plays a role in the development of other body systems, including the kidneys. The variation in the proteins that the gene produces can increase the risk of renal problems, such as the development of fluid-filled sacs known as cysts.

Individuals with RCAD may experience mild symptoms of diabetes. These can include:

• frequent urination
• increased thirst
• dehydration

In addition to diabetes symptoms, RCAD often affects other organs and manifests with extra-pancreatic symptoms. As the name suggests, these usually include structural changes to the kidneys that can affect their function and increase the risk of kidney conditions.

A person will also likely present with the following clinical features:

• early onset non-insulin-dependent diabetes
• kidney cysts
• kidney disease
• alterations in the genital tract
• high levels of uric acid and gout

Initially, a person may present with symptoms that suggest diabetes. A doctor will ask questions about the person’s symptoms and family history before performing a blood sugar test to confirm high blood sugar levels. They will then request additional tests, such as an autoantibody test, to help determine the type of diabetes.

Depending on these results, the doctor may suggest genetic testing, which is the gold standard for diagnosing MODY. Correctly identifying which type of diabetes a person has is important for optimizing treatment strategies. The MODY diagnostic guidelines recommend genetic testing if a person:

• has a diabetes diagnosis before the age of 25 years
• has a family history of diabetes
• can produce insulin
• has a C-peptide level in the normal range
• has a negative result for beta-cell autoantibodies

If the test identifies a mutation in the HNF1B gene, this result confirms a diagnosis of MODY 5.

Unlike other types of MODY, evidence suggests that individuals with RCAD often present with some level of insulin resistance. As such, common treatment options for MODY, such as sulfonylureas, are inefficient.

Instead, people may require insulin therapy to help treat the condition. It may also be advisable for a person to follow a diet plan from a dietitian to help them manage their blood sugar levels.

If an individual or child has symptoms of diabetes, it is advisable to consult a healthcare professional. An endocrinologist can help diagnose diabetes and determine the type.

In some cases, they may recommend genetic testing for MODY 5. This is possible if a person receives a diabetes diagnosis at a young age, has a known family history of the disease, and presents with symptoms that are not typical features of other diabetes conditions. A doctor may also be able to detect renal cysts in the womb before a baby is born, which may indicate RCAD.

Renal cysts and diabetes syndrome is a rare subtype of diabetes. It belongs to a group of conditions known as maturity onset diabetes of the young. It occurs due to an alteration in the HNF1B gene. This gene has a role in the development of beta cells and the kidneys. The gene mutation affects the production of insulin and the structure of the kidneys, which increases the risk of cysts.

Genetic testing is necessary to confirm a variation in the HNF1B gene and diagnose RCAD. Treatment for the condition typically involves insulin therapy and following a dietary regimen to help control blood sugars.