MCT1 deficiency - a rare disorder of the SLC16A1 gene

Key Facts

A rare genetic disorder of the SLC16A1 gene causes MCT1 deficiency, which affects ketone metabolism. MCT1 deficiency was first reported in 2014. By 2016, only 11 individuals globally had been identified in the research. The real prevalence is probably much higher than this.

NOTE: This content does not constitute medical advice, nor should it be treated as authoritative.

Issues almost always first appear in early childhood, usually with an unexpected bout of ketoacidosis.
MCT1 deficiency causes elevated ketones when children are unwell, or have high energy demands through exercise, or if they vomit or don't eat for an extended period.
Elevated ketones can lead to ketoacidosis - a serious condition, needing immediate hospital treatment.
Danger signs: tiredness, lethargy, 'racoon' eyes, elevated ketones. Serious danger signs: vomiting.
Medical emergency: Persistent vomiting, Kussmaul (deep) breathing, abnormal sleepiness, confusion, loss of consciousness.

Diabetes, if poorly controlled can lead to ketoacidosis. However, unexplained ketoacidosis could be MCT1 related in a non-diabetic patient.

First Aid / Treatment

Confirm elevated ketones, ideally via blood test (preferred) or urine test (if blood test not available).
First line treatment: oral carbohydrates (glucose) or, administer 10% dextrose/saline intravenously.
Aggressive management of ketoacidosis may be required.
Family Care Plans (password required)

With MCT1 deficiency as the cause, blood sugars sometimes remain normal during ketosis/ketoacidosis: glucose is urgently required, irrespective of measured blood glucose levels. Treating physicians unfamilar with MCT1 deficiency may determine that IV glucose is not required because of the normal blood sugar readings - this can be a fatal mistake.

Get in touch

Contact from families/medical personnel is welcomed. Get in touch to find out more, or to learn about our small network of affected families. We have learned a lot through our 20 year+ experiences and are willing to share our knowledge - hence this website.

Our email address is info@mct1.org (no spam please, unless you want your IP address submitted to global blacklists and reported to your internet provider).

We also have a private discussion forum, which we can tell you about after you reach out by email.

Key Papers

MCT1 deficiency was first reported in the New England Journal of Medicine in 2014, in Monocarboxylate Transporter 1 Deficiency and Ketone Utilization. Refer also to the Appendices (and the Editorial within that issue)
Reference: N Engl J Med 2014;371:1900-7. DOI: 10.1056/NEJMoa1407778

This paper was then followed by a paper focusing on a specific case of MCT1, titled Heterozygous Monocarboxylate Transporter 1 (MCT1, SLC16A1) Deficiency as a Cause of Recurrent Ketoacidosis
Reference: DOI 10.1007/8904_2015_519