This program promises to be profoundly life-changing for children in British Columbia who have a treatable intellectual disability. It has the potential to change practice around the world.
Larry Gold, President of BC Children’s Hospital and Sunny Hill Health Centre for Children.

TIDE revolutionizes the diagnostic and therapeutic approach to intellectual
disabilities through novel technologies and evidence-based medicine


Tide BC is a new collaborative care & research initiative with a focus on prevention and treatment of Intellectual disability (ID). We have shown that the ID seen in some children is due to treatable genetic conditions known as inborn errors of metabolism (IEM) . Many of these IEM’s can be treated with diet or drugs.
Presently, health care policy and institutional culture is still operating under the old premise that all ID is incurable and thus, many children born with treatable ID are at risk of not being treated.


At BC Children’s Hospital (BCCH) in Vancouver, Canada, 1500 patients with ID are seen for diagnostic assessment per year by various services, such as neurology, medical genetics, biochemical diseases, developmental pediatrics and child psychiatry. With the local expertise of all these specialists, existing diagnostic laboratory methods, and the major advances in diagnostic and therapeutic technologies, BCCH is the ideal academic location to implement our evidence-based protocol to identify treatable causes of ID.


What is intellectual disability (ID)?

ID is a debilitating condition with deficits in cognitive functioning (IQ < 70) and adaptive skills. Developmental delay (DD) is the term used in children < 5 years, who show deficits in two ore more developmental domains.

ID is often associated with behavioural problems (such as hyperactivity, autism, aggressive and self injurious behaviour), epilepsy and other neurological disabilities, resulting in a considerable psychological, social and economic burden to patients and families.

A full definition of ID, by the American Association on Intellectual and Developmental Disabilities (AAIDD), can be found by clicking this link.

How frequent is ID?

ID affects 2 - 3% of children and adults. This implies that in BC alone 800-1200 newborns per year will suffer ID.

What are the causes of ID?

Causes of ID are many. Therefore, to identify the origin of ID in a child can pose a huge challenge to doctors. Causes of ID may occur as early as in fetal life or any time later in life. Examples include noxious hits to the fetal brain due to alcohol (fetal alcohol syndrome) or infections during pregnancy or later in life. Apart from such environmental and acquired causes, genetic origin is an important cause of ID.

In more than 50% the cause of ID is genetic
Genetic causes by themselves are manifold and complex. Therefore many different tests are performed and many specialists are involved to elucidate those genetic causes.
Current guidelines for assessment of genetic ID are based on frequencies of single conditions and on the yield of diagnostic methods and procedures. Therefore cytogenetic techniques, such as karyotyping and array-CGH, which yield a causal diagnosis in 20% of cases, are considered priority. Despite high frequency and high diagnostic yield, no causal treatment is available for most of the conditions identified by these investigations.

What are treatable causes of ID?

What are treatable causes of ID? Inborn errors of metabolism (IEMs) constitute a subgroup of genetic ID accounting for 2.5% of diagnoses. It is this subgroup, however, that does include conditions, which are causally treatable. Despite the option to profoundly improve prognosis by implementing causal therapy, screening for IEMs is not performed systematically. This is explained by the fact that treatable IEMS are very rare and one wants to look at frequent conditions first. Another reason is the fact that there are no universal protocols summarizing comprehensively all IEMs causing treatable IDs. Furthermore there are no protocols indicating the type and order of tests to perform to make sure not to miss any of those conditions.

How many treatable IDs are there?

The number of treatable IDs is increasing. During the past two decades, an increasing number of IEMs have become amenable to treatments, and technologies for better recognition have been introduced into clinical and health care practice.

Therefore we undertook a systematic literature review to identify all treatable IEMs with ID as a predominant feature and to characterize types of treatments and evidence for effect. To our own surprise we identified as many as 81 ‘treatable IEMs’ presenting with ID as a major feature.

What treatments are available for rare diseases causing ID?

The type of treatment depends on, and is specific to each each rare inborn of metabolism. Most treatments are affordable, e.g. diet and vitamin/supplements, which do often require lifestyle adaptations. Others include more costly medications or more invasive interventions such as stemcell therapy. Only 1 of the 81 rare diseases requires an expensive medication (subastrate inhibitor); enzyme replacement therapy as causal treatment for ID is not on our list.

What is the dimension of health care costs for ID?

ID is the disease category with the largest health care costs - almost equal to the economic impact of stroke, heart disease, and cancer combined Meerding 1998.

How to diagnose treatable ID?

> 50% of all disorders are potentially identified by chemical tests in urine and blood. These group tests are easily available and relatively cheap. For the remaining disorders a ‘single test for single disease approach’ is necessary. Because tests to diagnose these disorders are not widely available, and / or expensive, they cannot be done for everyone, but only after specific hints have become available through an extensive clinical by an experienced specialist.

Why a new diagnostic approach to treatable ID?

The low frequency of these diseases should not prohibit an active process of identification. If we find more patients with treatable ID, we can improve their outcomes in many ways. In some, particularly young children treatment can halt progression of an otherwise ongoing developmental delay and preserve brain function. Other children may benefit because additional behavioural problems or epilepsy may improve on treatment. Even in the absence of causal therapy, determination of the genetic aetiology of ID is pivotal in generating and translating knowledge relevant to the anticipatory healthcare needs of the individual and their family –including genetic counselling- and minimizing gaps or disparities in care.

What is the new protocol?

A protocol which acknowledges treatable ID as a priority. The results of our systematic review prompted us to develop a protocol which can be used by every single physician as an aid to evaluate a child with developmental delay and ID. The premise of this protocol is to consider treatability at first place, to provide state of the art evaluation for non-treatable conditions at the same time, and ultimately to give room for integration of new diagnostic technologies as they become available for clinical application. This protocol received attention at international conferences and benefits from global collaboration.


TIDE-BC is the first Collaborative Area of Innovation funded through the BC Children's Hospital Foundation, Vancouver, Canada. To expand the project (inter-)nationally funding application is ongoing.

Copyright 2011 - 2016

All information on this website is under the copyright of the authors
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Contact Information

TIDE BC / Biochemical Diseases Clinic
BC Children's Hospital
Rm K3-208, ACB
4480 Oak Street
Vancouver, B.C. V6H 3V4

Phone: 604-875-2628 (administrative)
Phone: 604-875-2880 (clinic)
FAX: 604-875-2349