Bardet-Biedl syndrome

Published Categorized as Genetics
Bardet-Biedl syndrome

Bardet-Biedl Syndrome (BBS) is a rare genetic condition with a frequency of about 1 in 140,000 newborns and a citation in the literature dating back to the 1920s. It is a pleiotropic disorder, meaning it affects multiple body systems, and is associated with additional features such as obesity, intellectual disability, renal abnormalities, and polydactyly among others.

The syndrome is known to be caused by mutations in more than 20 genes, which are involved in various biological processes and have diverse functions. These genes are among a group known as ciliary or basal body genes, which play a crucial role in the development and function of cilia, tiny hair-like structures found on the surface of cells.

Research and clinical studies have provided valuable information about the condition. Studies have identified specific symptoms and clinical findings associated with BBS, expanding our understanding of this complex syndrome. The inheritance pattern of BBS is autosomal recessive, meaning that both parents must carry a mutation in the same gene for a child to be affected.

To date, there is no cure for BBS, but there are many resources available to support affected individuals and their families. Organizations such as the Bardet-Biedl Syndrome Foundation and the BBSome Project provide advocacy, information, and support for patients and families. Clinical trials and genetic testing are ongoing, aiming to develop targeted therapies and improve patient outcomes.

For more information about Bardet-Biedl Syndrome, the OMIM database and PubMed offer comprehensive resources with references to scientific articles and clinical trials. The ClinicalTrials.gov website provides updates on ongoing studies and testing related to BBS. Additionally, the National Human Genome Research Institute is a valuable center for genetic research and resources on rare diseases.

Frequency

The frequency of Bardet-Biedl syndrome (BBS) is estimated to be between 1 in 100,000 and 1 in 160,000 live births, making it a rare genetic condition. However, the frequency may vary among different populations and regions.

Studies have shown that BBS is more common in certain populations, such as individuals of North African or Middle Eastern descent, compared to other populations. Additionally, the condition is more frequently diagnosed in consanguineous families, where the parents are closely related by blood.

As more research and scientific studies are conducted, additional information about the frequency and associated features of BBS continues to emerge. The Online Mendelian Inheritance in Man (OMIM) catalog and scientific articles can provide more details and references on the condition for those seeking further information.

BBS has an autosomal recessive inheritance pattern, meaning that both parents must carry a copy of the mutated gene for their child to be affected. Genetic testing can help confirm a diagnosis and identify the specific genes involved.

Newborns with BBS may not exhibit obvious symptoms at birth, which can make early diagnosis challenging. However, as they grow older, affected individuals develop various clinical features associated with the syndrome.

It is important for individuals and families affected by BBS to seek support from advocacy organizations and clinical trial resources, such as ClinicalTrials.gov, to stay updated on the latest research, treatments, and support options available for this rare condition.

Causes

The Bardet-Biedl syndrome (BBS) is a rare genetic condition that affects multiple organ systems. It is a complex disorder with a variety of underlying genetic causes. Currently, mutations in at least 32 genes have been associated with BBS, with the majority identified in the BBS1, BBS2, BBS4, BBS5, BBS7, BBS9, BBS10, BBS12, BBS17, and BBS18 genes.

BBS is an autosomal recessive disorder, which means that affected individuals inherit two copies of the mutated gene, one from each parent. In some cases, both parents are carriers of the mutated gene and have no symptoms of the syndrome. The exact frequency of BBS in the general population is not known, but it is estimated to occur in approximately 1 in 100,000 to 160,000 newborns.

Genetic testing is available to confirm a diagnosis of BBS. This testing can identify mutations in the known BBS genes and help to determine the underlying cause of the syndrome. However, it is important to note that not all cases of BBS can be diagnosed through genetic testing, as there may be additional genes that have yet to be associated with the condition.

Research studies have shown that mutations in the BBS genes can affect the function of cilia, which are tiny hair-like structures found on the surface of many cells in the body. Cilia play a crucial role in various cellular processes, including signal transduction and fluid movement. When the cilia are not functioning properly, it can lead to the development of the characteristic features and diseases associated with BBS.

The specific signs and symptoms of BBS can vary widely among affected individuals. The most common features of the syndrome include retinal degeneration (causing vision impairment or blindness), obesity, kidney abnormalities, extra fingers or toes, developmental delay, and intellectual disability. However, there are other less common features that can occur, such as polydactyly (extra fingers or toes), dental abnormalities, and hearing loss.

Due to the rarity of BBS, it is important for affected individuals and their families to seek support and learn about the condition from advocacy and support groups. These resources can provide valuable information about the latest research, clinical trials, and other available resources for BBS patients and their families.

For more information about the causes of Bardet-Biedl syndrome, you can refer to the following scientific resources:

  • OMIM (Online Mendelian Inheritance in Man) – a comprehensive catalog of genes and genetic disorders
  • PubMed – a database of scientific articles
  • ClinicalTrials.gov – a registry of clinical trials

References:

  1. Beales, P.L., Elcioglu, N., Woolf, A.S., Parker, D., & Flinter, F.A. (1999). New criteria for improved diagnosis of Bardet-Biedl syndrome: results of a population survey. Journal of Medical Genetics, 36(6), 437-446.
  2. Ansley, S.J., Badano, J.L., Blacque, O.E., Hill, J., Hoskins, B.E., Leitch, C.C., Kimberling, W.J., Lewis, R.A., Leroux, M.R., & May-Simera, H.L. (2003). Basal body dysfunction is a likely cause of pleiotropic Bardet-Biedl syndrome. Nature, 425(6958), 628-633.
  3. Fan, Y., Esmail, M.A., Ansley, S.J., & Blacque, O.E. (2004). Bardet-Biedl syndrome genes are important in retrograde intracellular trafficking and Kupffer’s vesicle cilia function. Human Molecular Genetics, 13(5), 561-573.

Learn more about the genes associated with Bardet-Biedl syndrome

Bardet-Biedl syndrome is a genetic disorder characterized by a range of features including obesity, retinal degeneration, polydactyly (extra toes or fingers), intellectual disability, and kidney abnormalities. It is a rare condition, with an estimated frequency of 1 in 100,000 newborns.

While the exact causes of Bardet-Biedl syndrome are not fully known, research and studies have identified several genes that are associated with the condition. These genes are primarily involved in cilia function, which is essential for the proper development and function of various organs and tissues in the body.

The genes most commonly associated with Bardet-Biedl syndrome include BBS1, BBS2, BBS4, BBS5, BBS7, BBS8, BBS9, BBS10, BBS12, MKKS, and TRIM32. Variations or mutations in these genes can disrupt cilia function, leading to the clinical features observed in individuals with Bardet-Biedl syndrome.

Studies have shown that individuals with Bardet-Biedl syndrome often have mutations in multiple genes, suggesting a complex genetic inheritance pattern. In addition, other genes not specifically associated with Bardet-Biedl syndrome have also been found to contribute to the development of the condition, such as ALMS1 and CEP290.

To learn more about the genes associated with Bardet-Biedl syndrome and their functions, you can refer to resources such as the Online Mendelian Inheritance in Man (OMIM) database and scientific articles available on PubMed. These resources provide comprehensive information on the genes, their known functions, and their role in Bardet-Biedl syndrome.

If you or someone you know is affected by Bardet-Biedl syndrome, genetic testing can help identify variations or mutations in the associated genes. This information can be useful for diagnosis, prognosis, and genetic counseling.

In addition to genetic testing, there are also various resources available for individuals and families affected by Bardet-Biedl syndrome. Support groups and advocacy organizations, such as the Bardet-Biedl Syndrome Foundation and the National Organization for Rare Disorders (NORD), can provide guidance, support, and information on available treatments, clinical trials, and research opportunities for the condition.

References:

  1. Katsanis N. (2004). The oligogenic properties of Bardet-Biedl syndrome. Hum Mol Genet. 13 Spec No 1, R65-71. doi: 10.1093/hmg/ddh073
  2. Moore SJ, et al. (2005). Clinical and genetic epidemiology of Bardet-Biedl syndrome in Newfoundland: A 22-year prospective, population-based, cohort study. Am J Med Genet A. 132A(4), 352-360. doi: 10.1002/ajmg.a.30444
  3. OMIM. Bardet-Biedl syndrome. Retrieved from https://www.omim.org/entry/209900

Inheritance

The Bardet-Biedl syndrome (BBS) is a rare genetic condition that affects multiple systems in the body. The syndrome is inherited in an autosomal recessive pattern, which means that an individual must inherit two copies of the mutated gene, one from each parent, in order to develop the condition.

There are currently over 20 known genes associated with BBS, which are responsible for various functions among the affected individuals. Some of these genes include BBS1, BBS2, BBS3, BBS4, and BBS5, among others.

See also  NOTCH2 gene

Genetic testing can be used to confirm a diagnosis of BBS in a patient. This testing can identify mutations in the known BBS genes and provide important information about the inheritance of the condition in a family.

Research studies have shown that the frequency of BBS in newborns is estimated to be around 1 in 160,000. However, the actual frequency may be higher as the condition often goes undiagnosed or misdiagnosed due to its rarity and the variability of its features.

The exact causes of BBS are not yet fully understood, but it is believed to be linked to the malfunction of cilia, which are tiny hair-like structures found on the surface of cells. These cilia play important roles in various cellular processes, including sensory perception and signal transduction. Mutations in the BBS genes disrupt the normal function of cilia, leading to the development of the condition.

Additional information and resources on BBS can be found on various websites and support centers, including the Bardet-Biedl Syndrome Foundation, OMIM (Online Mendelian Inheritance in Man), and PubMed. These resources provide valuable scientific articles, clinical trials information, and advocacy support for individuals and families affected by BBS.

It is important for healthcare professionals and genetic counselors to stay up-to-date with the latest research and information on BBS to provide accurate diagnosis and management of the condition. The development of clinical trials and the cataloging of information on affected individuals can further advance our understanding of BBS and potentially lead to improved treatment options in the future.

References:

  1. Beales PL. BBS genes and cilia function. Cilia. 2011;1(1):16. doi:10.1186/2046-2530-1-16.
  2. Aldahmesh MA, Li Y, Alhashem A, et al. IFT27, encoding a small GTPase component of IFT particles, is mutated in a consanguineous family with Bardet-Biedl syndrome. Hum Mol Genet. 2014;23(12):3307-3315. doi:10.1093/hmg/ddu043.
  3. “Bardet-Biedl syndrome.” Genetic and Rare Diseases Information Center. Accessed October 5, 2021. https://rarediseases.info.nih.gov/diseases/6441/bardet-biedl-syndrome.

Other Names for This Condition

Bardet-Biedl syndrome is known by several other names, including:

  • Laurence-Moon syndrome
  • Laurence-Moon-Biedl syndrome
  • Laurence-Moon-Bardet-Biedl syndrome
  • Bardet-Biedl retina-renal syndrome
  • Bardet-Biedl syndrome 1 (BBS1)
  • Bicuspid aortic valve Bardet-Biedl syndrome
  • Laurence-Moon-Bardet-Biedl syndrome-6 (BBS6)

These names reflect the historical development of our understanding of this syndrome and the various signs and symptoms associated with it. As more research and testing are done, additional information may become available.

Research studies and clinical trials are ongoing to learn more about Bardet-Biedl syndrome and its genetic causes. ClinicalTrials.gov and OMIM are valuable resources for information on ongoing studies and genetics research related to this condition.

It is important for affected individuals and their families to stay informed about new developments in Bardet-Biedl syndrome and to seek support from advocacy organizations and other rare disease communities.

Genetic testing, newborn screening, and clinical evaluation are available to help diagnose Bardet-Biedl syndrome. Early diagnosis can lead to more effective management and support for individuals with the condition.

For a more comprehensive list of the associated features, genes, and inheritance pattern of Bardet-Biedl syndrome, please refer to the resources and references cited in scientific articles and databases such as PubMed, OMIM, and the BBS genetic testing catalog.

Additional Information Resources

The Bardet-Biedl syndrome is a rare genetic condition with multiple features that develop in affected individuals. The exact causes of this condition are not yet fully understood, but research has identified several known genes associated with Bardet-Biedl syndrome. Inheritance of the syndrome can occur through both autosomal recessive and autosomal dominant patterns.

For more information on the genetic basis of Bardet-Biedl syndrome, the Online Mendelian Inheritance in Man (OMIM) database provides a comprehensive catalog of genes and diseases. The Beales Genetic Bardet-Biedl Syndrome Gene Testing Center also offers genetic testing and support for individuals with Bardet-Biedl syndrome.

Newborns with Bardet-Biedl syndrome may display various clinical features, including obesity, impaired kidney function, vision problems, and extra fingers or toes. It is important for healthcare professionals to consider the possibility of Bardet-Biedl syndrome in newborns with these features and support further testing if necessary.

If you are interested in participating in research studies or clinical trials related to Bardet-Biedl syndrome, you can find more information on ClinicalTrials.gov. This online database provides updates on ongoing scientific research and studies targeting rare genetic conditions, including Bardet-Biedl syndrome.

To learn more about Bardet-Biedl syndrome and find articles and scientific research papers on the topic, you can refer to the PubMed database. PubMed is a valuable resource for finding information on rare genetic conditions and associated research.

In addition to these online resources, there are advocacy organizations and patient support groups that provide information and support to individuals and families affected by Bardet-Biedl syndrome. These organizations often have websites with more detailed information and resources.

References:

Genetic Testing Information

Bardet-Biedl syndrome (BBS) is a rare condition caused by mutations in various genes. Research on this genetic disorder has identified multiple genes associated with BBS, including BBS1, BBS2, BBS3, BBS4, BBS5, BBS6, BBS7, BBS8, BBS9, BBS10, BBS11, BBS12, MKKS, and BBS14. The Online Mendelian Inheritance in Man database (OMIM) provides a comprehensive catalog of information on these genes and the condition they cause.

Genetic testing is recommended for individuals suspected to have Bardet-Biedl syndrome. This testing can help confirm the genetic cause of the condition and provide additional information about the specific genes involved. Several scientific articles and studies have been published on the inheritance patterns and functions of these genes in BBS.

One study by Beales et al. (2003) identified additional causes of BBS, such as mutations in ALMS1 and IFT27 genes. These findings highlight the genetic complexity of the syndrome and the need for comprehensive testing to accurately diagnose affected patients.

It is important to note that not all individuals with BBS will have mutations in the known BBS genes. This suggests that there may be other, as yet unidentified, genetic causes of the syndrome. Ongoing research aims to discover these additional genetic factors.

Genetic testing for Bardet-Biedl syndrome can be performed using various methods, including targeted gene sequencing, whole exome sequencing, or whole genome sequencing. The frequency of genetic mutations in BBS genes can vary among different populations, and testing should be tailored accordingly.

For newborns with suspected BBS, early genetic testing can provide valuable information to guide clinical management and support the affected child’s development. Parents and caregivers can also benefit from genetic testing to understand the inheritance pattern and recurrence risks for future pregnancies.

There are several resources available for individuals seeking more information about genetic testing for Bardet-Biedl syndrome. ClinicalTrials.gov maintains a database of ongoing and completed clinical trials related to BBS. The National Center for Biotechnology Information’s PubMed database contains a wealth of scientific articles on the genetics and clinical features of BBS. Additionally, organizations such as the Bardet-Biedl Syndrome Foundation provide support, advocacy, and educational materials for affected individuals and their families.

Genes Known Associated with BBS
BBS1 Yes
BBS2 Yes
BBS3 Yes
BBS4 Yes
BBS5 Yes
BBS6 Yes
BBS7 Yes
BBS8 Yes
BBS9 Yes
BBS10 Yes
BBS11 Yes
BBS12 Yes
MKKS Yes
BBS14 Yes
ALMS1 Additional causes identified
IFT27 Additional causes identified

References:

  1. Beales, P.L., Elcioglu, N., Woolf, A.S., Parker, D., Flinter, F.A. (2003). New criteria for improved diagnosis of Bardet-Biedl syndrome: results of a population survey. Journal of Medical Genetics, 40(5), 374-378.

This article was written with support from the Bardet-Biedl Syndrome Foundation.

Genetic and Rare Diseases Information Center

The Genetic and Rare Diseases Information Center (GARD) is part of the National Institutes of Health (NIH) and provides up-to-date and reliable information about Bardet-Biedl syndrome and other rare genetic conditions.

Bardet-Biedl syndrome is a rare genetic condition that affects multiple parts of the body. It is characterized by a combination of physical features, such as obesity, vision loss, extra fingers or toes, and intellectual disability. Other additional features may include kidney abnormalities, heart defects, and hearing loss.

Bardet-Biedl syndrome is caused by genetic changes in several different genes, including BBS1, BBS2, BBS4, and more. It is inherited in an autosomal recessive manner, which means that an individual must inherit two copies of the mutated gene, one from each parent, to develop the condition.

Although the exact frequency of Bardet-Biedl syndrome is unknown, it is considered a rare condition. It affects males and females equally. Symptoms can vary widely among affected individuals, even within the same family.

If you suspect that you or a loved one may have Bardet-Biedl syndrome, it is important to seek medical attention and undergo genetic testing for a definitive diagnosis. Early testing can help provide critical information about the condition and guide appropriate treatment and management strategies.

In addition to genetic testing, other clinical studies and research are ongoing to better understand the causes, features, and inheritance of Bardet-Biedl syndrome. These studies aim to improve our knowledge of the condition and develop potential treatments or therapies.

See also  RPS14 gene

For more information about Bardet-Biedl syndrome, you can visit the GARD website and search for the condition using the official name or other associated names, such as Laurence-Moon-Bardet-Biedl syndrome or BBS. The GARD website provides a wealth of resources, including articles, references, and citation from scientific publications and clinical trials. You can also learn about advocacy and support groups that may offer additional information and assistance.

References:

Patient Support and Advocacy Resources

The Bardet-Biedl syndrome is a rare genetic condition that affects multiple organ systems and is associated with a wide range of clinical features. Patients and their families often face various challenges in managing the condition and accessing appropriate resources. Fortunately, there are several patient support and advocacy resources available to help individuals affected by Bardet-Biedl syndrome.

  • Bardet-Biedl Syndrome Family Association (BBSFA): The BBSFA is a patient support organization dedicated to improving the lives of individuals and families affected by Bardet-Biedl syndrome. They provide valuable information, resources, and support for patients and their families.
  • Patient Advocates for Rare Diseases (PARD): PARD is a non-profit organization that offers support and advocacy for individuals with rare diseases, including Bardet-Biedl syndrome. They work to raise awareness about the condition and advocate for better access to healthcare services and resources.
  • Rare Diseases Clinical Research Network (RDCRN): The RDCRN is a network of research centers focused on rare diseases, including Bardet-Biedl syndrome. They conduct research studies and clinical trials to advance the understanding and treatment of rare genetic conditions. Patients can find information about ongoing studies and clinical trials on the RDCRN website.
  • Online Genetic Testing Databases: There are several online genetic testing databases that individuals with Bardet-Biedl syndrome can use to find information about their specific genetic mutations. These databases include OMIM (Online Mendelian Inheritance in Man) and the Genetic Testing Registry, which provide detailed information about the genes and inheritance patterns associated with Bardet-Biedl syndrome.
  • Scientific Articles and Research Studies: Patients and their families can stay updated on the latest scientific research and discoveries related to Bardet-Biedl syndrome by accessing scientific articles and research studies. PubMed and the Journal of Medical Genetics are reputable sources for finding relevant articles and research studies.

By utilizing these patient support and advocacy resources, individuals affected by Bardet-Biedl syndrome can access additional information, support, and resources to help manage the condition and improve their overall quality of life.

Research Studies from ClinicalTrials.gov

Rare genetic diseases like Bardet-Biedl syndrome have been a subject of extensive research in the scientific community. ClinicalTrials.gov provides a comprehensive catalog of ongoing research studies for various rare diseases, including Bardet-Biedl syndrome.

This platform serves as a valuable resource for both researchers and patients, offering information about clinical trials and other research studies aimed at understanding the condition better and developing effective treatments.

Research studies on Bardet-Biedl syndrome are essential as this rare genetic disorder affects multiple systems and can present with a wide range of features. By investigating the underlying genetic causes and testing new treatment options, scientists hope to improve the quality of life for affected individuals.

One of the known causes of Bardet-Biedl syndrome is genetic mutations. More than 20 genes have been identified to be associated with this condition, and ongoing research aims to expand the understanding of these genes and their role in the development of the syndrome.

ClinicalTrials.gov provides additional information on patient advocacy groups, genetic testing centers, and other resources to support individuals and families affected by Bardet-Biedl syndrome. These resources can help individuals access genetic testing and learn more about the condition.

The frequency of Bardet-Biedl syndrome is relatively low, making it a rare condition. However, research studies have found that the syndrome is more common in certain populations, indicating potential genetic and environmental factors influencing its occurrence.

By examining the genetic inheritance patterns and studying affected individuals from different populations, researchers aim to gain a better understanding of the causes and effects of Bardet-Biedl syndrome. This knowledge can then contribute to the development of targeted treatments and interventions.

ClinicalTrials.gov also offers references to articles and studies published in PubMed that provide further insight into Bardet-Biedl syndrome. These articles contribute to the scientific knowledge base and support ongoing research efforts.

In conclusion, research studies from ClinicalTrials.gov play a crucial role in advancing our understanding of Bardet-Biedl syndrome. Through scientific investigation, we can learn more about the genetic causes, clinical features, and possible treatments for this rare condition. The collaborative efforts of researchers, advocacy groups, and genetic testing centers help support individuals with Bardet-Biedl syndrome and contribute to ongoing research in the field.

Catalog of Genes and Diseases from OMIM

The Catalog of Genes and Diseases from OMIM is a comprehensive resource for information about genetic conditions and associated genes. OMIM, or Online Mendelian Inheritance in Man, is a database that catalogs genetic diseases and the genes associated with them.

The catalog includes names and descriptions of genetic diseases, as well as information about their clinical features, inheritance patterns, and known causes. It also provides references to scientific articles and resources for further research, such as PubMed and ClinicalTrials.gov.

Bardet-Biedl syndrome (BBS) is among the genetic conditions listed in the catalog. BBS is a rare genetic disorder that affects multiple organs and systems in the body. It is associated with mutations in various genes, including BBS1, BBS2, BBS4, and BBS6, among others.

Affected individuals usually develop symptoms in infancy or early childhood. These can include vision problems, extra fingers or toes, obesity, and intellectual disability. BBS is known for its wide range of clinical features, with additional symptoms varying from patient to patient.

Genetic testing can be done to identify the specific gene mutations causing BBS in an individual. This information can help with diagnosis, determine inheritance patterns, and provide useful information for genetic counseling.

The catalog from OMIM provides a wealth of information about Bardet-Biedl syndrome, including genetic testing resources and research articles. It also offers support and advocacy center information for affected individuals and their families, such as the BBS Family Association and the National Organization for Rare Disorders.

Learn more about Bardet-Biedl syndrome and other rare genetic diseases by exploring the Catalog of Genes and Diseases from OMIM. It is an invaluable resource for researchers, clinicians, and individuals seeking information about genetic conditions and associated genes.

Scientific Articles on PubMed

PubMed is a valuable resource for researchers and healthcare professionals as it provides access to a vast collection of scientific articles related to various medical conditions. This includes Bardet-Biedl syndrome, a rare genetic disorder characterized by a combination of physical and developmental features.

By searching PubMed, researchers can access scientific articles that focus on the development and testing of new diagnostic tools, treatment options, and therapeutic resources for Bardet-Biedl syndrome. These articles provide valuable insights into the causes, inheritance patterns, and associated features of the condition.

Some articles on PubMed also discuss specific genes that are affected in Bardet-Biedl syndrome, such as BBS1, BBS2, BBS4, and BBS6. These genes are known to play a role in the function of cilia, which are tiny, hair-like structures found on the surface of cells. Mutations in these genes can lead to the development of Bardet-Biedl syndrome, as well as other ciliopathies.

In addition to providing information about the genetic causes and features of Bardet-Biedl syndrome, PubMed also offers resources for patient advocacy and support. These resources include patient support groups, genetic counseling services, and clinical trials that are aimed at testing new therapies or gathering additional information about the condition.

Researchers and healthcare professionals can also benefit from the scientific articles on PubMed by staying up-to-date with the latest research on Bardet-Biedl syndrome. This can help inform clinical practice, guide treatment decisions, and contribute to further research in the field.

In conclusion, PubMed offers a wide range of scientific articles on Bardet-Biedl syndrome that cover topics such as its genetic causes, associated features, inheritance patterns, and treatment options. By accessing these resources, researchers and healthcare professionals can learn more about this rare genetic syndrome and contribute to the development of better diagnostic and therapeutic approaches.

References

Peter Reeves

By Peter Reeves

Australian National Genomic Information Service, including the database of BioManager, has been maintained for a long time by Peter Reeves, a professor at the University of Sydney. Professor Reeves is internationally renowned for his genetic analysis of enteric bacteria. He determined the genetic basis of the enormous variation in O antigens.