The Power of a Genetic Diagnosis
This film about the power of a genetic diagnosis was developed by NHS Health Education England in collaboration with the Royal College of Physicians, with development led by Dr Kate Tatton-Brown and Dr Katherine Josephs at St George’s Hospital, London.
The little boy in this video is Arvin. Arvin was first seen at the genetics clinic at St George’s NHS Hospitals Trust in London when he was around one year old.
His parents had brought him to be seen by expert clinical geneticists because they wanted to know and understand the underlying cause of his complex neurodevelopmental disorder, so that they could best support him and for future family planning.
The story of Arvin’s journey to diagnosis, as told by his mother, is not uncommon but using new genomic technology we are beginning to see a change in the speed and accuracy of the diagnosis of children with neurodevelopmental disorders and an end to the ‘diagnostic odyssey’ for patients like Arvin.
When Arvin was first seen in the genetics clinic, at just over a year old he underwent a battery of traditional tests, such as chromosome microarray, in order to establish a reason for his challenges.
All of these tests failed to identify the underlying cause of Arvin’s disorder, and he and his family remained without a diagnosis.
At three years old, Arvin’s DNA sample was sent to the Congenica clinical interpretation team for rapid exome sequencing and analysis.
3 ½ weeks later Arvin’s physician received the exome sequencing report, which showed that a variant in the DHDDS gene was the underlying cause of his disorder, enabling a genetic diagnosis to be made.
The DHDDS gene encodes an essential component of a complex pathway required for the biosynthesis of several classes of glycoproteins, and causal variants in this gene result in a rare disorder characterized by neurodevelopmental delay and early onset seizures; a match for Arvin’s symptoms
In this video Arvin’s mother describes the power of a genetic diagnosis and the profound effect it has had on their family, enabling better access to personalized support for her son and accurate counselling for family planning.
The exome test also allowed the medical team looking after the family to determine that the DHDDS gene variant was not present in her unborn child, reassuring the family that her second child was very unlikely to be affected.
The video highlights the challenges faced by families like Arvin’s and the imp of genomics to provide timely diagnoses, changing the lives of patients and providing certainty for families
What is a neurodevelopmental disorder?
Neurodevelopmental disorders can be described as a group of disorders in which the development of the central nervous system has been disrupted.
They are usually detected in early infancy and can manifest with a wide range of signs and symptoms including, learning problems, language delay and impaired motor function; they may also be accompanied by other congenital anomalies.
Epilepsy is unfortunately common in children with neurodevelopmental disorders.
Why are neurodevelopmental disorders so difficult to diagnose?
Neurodevelopmental disorders themselves are quite common, with neurodevelopmental delay reported to affect 3-4% of children and young people, but in the absence of birth trauma, healthcare professionals and parents often do not understand why a developmental disorder has occurred.
In recent years several large studies have shown that many affected children have an underlying error in their genes. Unfortunately, the studies have also shown that the genetic causes of neurodevelopmental disorders are many and diverse with over 1,500 genetic loci1,2 and the number of genes implicated continuing to rise3.
This extensive genetic heterogeneity represents a diagnostic challenge for even for the most experienced physician, as often each child presents with a unique set of signs or symptoms.
Diagnosing neurodevelopmental disorders with genomics
Advances in genomics have introduced new approaches, unlocking the power of a genetic diagnosis in conditions such as neurodevelopmental disorders, empowering healthcare professionals to provide life-changing answers for patients and their families.
One particular example is exome sequencing, which ensures that all currently known genes can be examined simultaneously, rather than one by one.
Studies have shown that exome sequencing and analysis can identify the underlying genetic cause in >40% affected individuals3-6, but until recently, access to exome sequencing and data analysis technology was often centralized, limited, and reliant on access to bioinformatics expertise.
Excitingly, this is no longer the case, as exome and genome sequencing become more affordable and end-to end solutions for data processing, data analysis and clinical decision support are available to enable clinical experts to focus on diagnosing their own patients, an approach which has been shown to improve rates of diagnosis7.
Enabling the delivery of world class genomic medicine services
Congenica is a clinical decision support platform designed to rapidly assess genomic data and provide healthcare professionals with answers that enable a fast and accurate diagnosis in rare and complex genetic diseases, like Arvin’s.
The Congenica clinical decision support platform streamlines secondary and tertiary pipelines, for sequencing alignment, variant calling and annotation, and data interpretation to enable clinical and scientific experts to accurately and rapidly interrogate genomic data both for patient diagnosis and research.
Find out more about the impact of Congenica, enabling genomic medicine
- Shashi V, et al. The utility of the traditional medical genetics diagnostic evaluation in the context of next-generation sequencing for undiagnosed genetic disorders. Genet Med. 2014 Feb;16(2):176-82.
- The Development Disorder Genotype – Phenotype Database (DDG2P). https://decipher.sanger.ac.uk/ddd#ddgenes
- Wright CF, et al. Making new genetic diagnoses with old data: iterative reanalysis and reporting from genome-wide data in 1,133 families with developmental disorders. Genet Med. 2018 Oct;20(10):1216-1223.
- de Ligt J, et al. Diagnostic Exome Sequencing in Persons with Severe Intellectual Disability. N Engl J Med. 2012 Nov 15;367(20):1921-9
- Deciphering Developmental Disorders Study. Large-scale discovery of novel genetic causes of developmental disorders. Nature. 2015 Mar 12;519(7542):223-8
- Reuter MS, et al. Diagnostic Yield and Novel Candidate Genes by Exome Sequencing in 152 Consanguineous Families With Neurodevelopmental Disorders. JAMA Psychiatry. 2017 Mar 1;74(3):293-299
- Clark MM, et al. Meta-analysis of the diagnostic and clinical utility of genome and exome sequencing and chromosomal microarray in children with suspected genetic diseases. NPJ Genom Med. 2018 Jul 9;3:16.