What is it?
Bloom syndrome is a rare genetic condition characterised by growth deficiency leading to short stature, a sun sensitive rash (primarily across the nose and cheeks), decreased immune response and increased cancer susceptibility. These cancers primarily include leukaemia, lymphomas and colorectal cancer and can affect patients from a younger age than in the normal population. Patients also can have increased insulin resistance that presents similarly to type 2 diabetes mellitus and distinctive facial features including a long, narrow face, a small jaw and large ears.
What causes it?
Bloom syndrome is in most cases caused by mutation in the BLM gene on chromosome 15. This gene helps unwind DNA for replication and repair. BS is inherited in an autosomal recessive pattern, meaning the altered variant must be inherited by both parents. People with one mutated gene copy (known as carriers) typically have no symptoms. Male patients with Bloom syndrome are typically infertile due to poor sperm production whilst female fertility can vary. Some may experience reduced fertility or early menopause, whilst others maintain normal fertility. If a person with Bloom syndrome has a child with someone who is unaffected, all children will be carriers but unaffected themselves.
How is it diagnosed?
Although Bloom syndrome is primarily identified through clinical features and symptoms, genetic testing can identify mutations in the BLM gene and cytogenetic testing can identify any chromosomal instabilities. Sister chromatid exchange, a type of chromosome analysis is the diagnostic test and appears in much higher rates in patients with Bloom syndrome.
Can it be treated?
Whilst there is no cure for Bloom Syndrome, there are ways of managing it. Early and regular screenings for cancer are crucial, alongside monitoring immunity and infections. Avoiding the Sun where possible and using Sun protection helps manage skin manifestations and monitoring growth with nutrition supplementation if needed.
What is the Bloom’s Syndrome Rare Diseases Collaborative Network (RDCN)?
Rare disease collaborative networks (RDCNs) are initiatives formed by NHS England and NHS Improvement to improve the care, diagnosis, and treatment of individuals affected by rare diseases, including Bloom syndrome.
The Bloom Syndrome Clinical Network is comprised of two different NHS trusts, Guys and St Thomas’ NHS Foundation Trust, and its lead being Royal Manchester Children’s Hospital. The network is dedicated to developing an increased understanding and progressing research regarding Bloom syndrome as current expertise is scarce and collaboration is beneficial.
For more information or to get involved, you can contact the NHS England Rare Disease Collaborative Networks team at england.rdcns@nhs.net.
Credits:
Alya Howard – University of Mancheser 5th year medical student