Bardet-Biedl syndrome 8

Bardet-Biedl syndrome 8 (BBS8) is an autosomal recessive disorder characterized by a combination of physical and developmental abnormalities.

Key Features:

• Retinitis Pigmentosa: A progressive eye disease that leads to vision loss.
• Obesity: Excessive weight gain, particularly in the trunk area.
• Postaxial Polydactyly: Extra fingers or toes, specifically on the outer side of the hand or foot.
• Hypogonadism: Decreased function of the male gonads, leading to hormonal imbalances and potential reproductive issues.
• Developmental Delay: Slowed physical and cognitive development.

Genetic Cause: BBS8 is caused by homozygous mutations in the TTC8 gene on chromosome 14q31. This genetic mutation leads to the characteristic symptoms of BBS8.

References:

• Ansley et al., 2003 [1, 5, 9] describe BBS8 as an autosomal recessive disorder with the above-mentioned features.
• OMIM (Online Mendelian Inheritance in Man) entry for BBS8 provides a general phenotypic description and discusses genetic heterogeneity of Bardet-Biedl syndrome. [from OMIM #15]
• A number sign (#) is used with this entry because Bardet-Biedl syndrome-8 (BBS8) is caused by homozygous mutations in the TTC8 gene (608132). [from OMIM #15]

Bardet-Biedl syndrome (BBS) is a rare genetic disorder that affects multiple systems in the body. The signs and symptoms of BBS can vary from person to person, but common ones include:

• Obesity: Early-onset obesity is a prominent symptom of BBS, particularly around the torso and abdomen [6].
• Visual impairment: Individuals with BBS often experience visual problems, including retinal dystrophy, which can lead to decreased visual acuity and night blindness [3][5].
• Learning disabilities: Cognitive impairment and learning disabilities are also common symptoms of BBS [7].
• Polydactyly: Extra fingers or toes (polydactyly) are a characteristic feature of BBS [4][6].
• Reproductive abnormalities: Males with BBS may experience reduced function of the testes, while females may have reproductive issues [4][7].
• Kidney disease: Kidney defects and kidney disease can also occur in individuals with BBS [4][5].
• Hyperphagia: Some people with BBS may experience hyperphagia, which is an increased appetite leading to excessive food intake [2].

These symptoms often appear at birth or during early childhood. Early diagnosis and management of BBS are crucial for improving the quality of life for individuals affected by this condition.

References: [1] Not provided (since there's no relevant information on this topic) [2] Obesity and hyperphagia in BBS: Likely driven by impairment of a key signaling pathway that regulates hunger [3] Rod-cone or choroidal dystrophy causes decreased visual acuity, night blindness, photophobia and loss of central and color vision by late childhood/early adulthood. [4] Common symptoms include obesity, visual impairment, additional fingers and/or toes, reduced function of the testes in boys, kidney defects and learning disabilities [5] Symptoms of BBS · Polydactyly · Obesity · Retinal dystrophy · Kidney disease · Reproductive abnormalities · Cognitive impairment · Other symptoms. [6] Primary symptoms · obesity, especially around the torso and abdomen · visual impairment · learning disabilities · polydactyly (extra fingers or toes) ... [7] BBS is usually diagnosed in infancy. Common symptoms include obesity, visual impairment, additional fingers and/or toes, reduced function of the testes in boys, ...

Bardet-Biedl syndrome (BBS) 8 is a rare genetic disorder that affects multiple systems in the body. Diagnostic tests for BBS 8 are crucial for confirming the diagnosis and ruling out other conditions.

Available Genetic Tests

According to search results, genetic testing may help confirm the diagnosis of BBS 8 [5]. Molecular Vision Laboratory offers clinical genetic tests for various conditions, including BBS 8 [2].

Whole-Exome Sequencing

Recent studies have shown that whole-exome sequencing is now a first-line diagnostic test for patients with multiple congenital anomalies, rather than targeted sequencing [3]. This approach can help identify the underlying genetic cause of BBS 8.

Diagnostic Criteria

The diagnosis of BBS 8 is based on clinical manifestations and can be confirmed by genetic testing. According to Beales' modified diagnostic criteria, the presence of four primary features or three primary plus two secondary features is required [8].

Genetic Testing for BBS 8

Genetic testing may help confirm the diagnosis of BBS 8 in patients with a clinical suspicion or diagnosis of the condition [4]. Analysis methods include whole-exome sequencing and targeted sequencing.

Age-Related Considerations

It's worth noting that genetic testing may be recommended for children as young as 8-9 years old, especially if they exhibit symptoms suggestive of BBS 8 [5].

In summary, diagnostic tests for Bardet-Biedl syndrome 8 include:

• Genetic testing (whole-exome sequencing and targeted sequencing)
• Clinical genetic tests offered by Molecular Vision Laboratory
• Diagnostic criteria based on clinical manifestations and confirmed by genetic testing

References: [1] Not applicable [2] Context result 2 [3] Context result 3 [4] Context result 4 [5] Context result 5 [8] Context result 8

Current Drug Treatments for Bardet-Biedl Syndrome

According to recent studies, there are promising results in the use of setmelanotide, a melanocortin 4 receptor agonist, as a potential treatment for Bardet-Biedl syndrome (BBS) [8]. Setmelanotide has been studied through subcutaneous injection and has shown positive outcomes in managing certain symptoms associated with BBS.

Key Points:

• Setmelanotide is being researched as a potential treatment for BBS.
• The medication targets the melanocortin 4 receptor, which may help alleviate some symptoms of the condition.
• Subcutaneous injections have been used to administer setmelanotide in studies.

Please note that while these findings are promising, further research and clinical trials are necessary to fully understand the efficacy and safety of setmelanotide as a treatment for BBS.

Differential Diagnoses for Bardet-Biedl Syndrome

Bardet-Biedl syndrome (BBS) has several differential diagnoses, which are conditions that can present with similar symptoms and characteristics. Some of the main differential diagnoses include:

• Alström Syndrome: This is a rare genetic disorder that affects multiple organs, including the eyes, kidneys, and reproductive system. Patients with Alström syndrome often experience early-onset retinopathy, nystagmus, and obesity [6].
• McKusick-Kaufman Syndrome: This is another rare genetic disorder that can present with similar symptoms to BBS, including polydactyly, obesity, and renal dysfunction.
• Joubert Syndrome: This is a rare genetic disorder that affects the development of the brain and spinal cord. Patients with Joubert syndrome often experience respiratory problems, hypotonia, and eye movement abnormalities [1].
• Jeune Syndrome: Also known as asphyxiating thoracic dystrophy, this is a rare genetic disorder that affects the development of the lungs and ribcage.
• Sensenbrenner Syndrome: This is another rare genetic disorder that can present with similar symptoms to BBS, including polydactyly, obesity, and renal dysfunction.

These differential diagnoses are important to consider when diagnosing BBS, as they can have overlapping symptoms and characteristics. A thorough medical evaluation and genetic testing are often necessary to confirm a diagnosis of BBS [8].

References: [1] - Context 1 [6] - Context 6