Biochemical Genetics

Biochemical Genetics provides a regional diagnostic and monitoring service for the investigation of inherited metabolic disease. Routine analyses provided by the department include urine and plasma amino acids (qualitative and quantitative), urine organic acids and bloodspot acylcarnitines.

In addition the laboratory is a specialist national referral centre for the investigation of peroxisomal disorders (very long chain fatty acid, pristanic acid and phytanic acid analysis), galactosaemia (qualitative and quantitative enzyme analysis, Galactose-1-phosphate and urine galactitol) and Smith Lemli-Opitz syndrome (7 dehydrocholesterol and 8 dehydrocholesterol analysis). Prenatal diagnosis is available for galactosaemia and Smith Lemli-Opitz syndrome.

We provide a comprehensive advisory service and welcome discussions to inform appropriate patient investigation and result interpretation. Clinical advice and interpretation is available during working hours, through the key contacts below. Consultant cover is also provided via the main hospital switchboard.

Details for Sample Requirements and Transport can be found under ‘Requesting’ and ‘Blood test information’ via the menu at the top of this page. Please see the Clinics page for details of our adult metabolic clinic.

Additional tests

Additional tests can be arranged on samples already received by our laboratory, please telephone us. Please note that samples received in biochemical genetics are routinely stored for 4 - 8 weeks. Sometimes there may be insufficient remaining sample to perform any extra tests.

If you would like to discuss which tests may be useful in different clinical scenarios please contact us.

Galactosaemia Investigations:


Disorder suspected



Classical Galactosaemia

Galactokinase deficiency

Epimerase deficiency


Galactosaemia Screen

First line if NOT transfused




First line if transfused*
(Sometimes used for monitoring treatment)

First Line

Monitoring treatment


Galactose-1-phosphate (Gal-1-P)

Monitoring treatment

Monitoring treatment


(Sometimes used for monitoring treatment)

Galactose-1-phosphate uridyl transferase


Identification of carriers and variants











*If classical galactosaemia is suspected in a baby that has had a red blood cell transfusion, advise contacting Southmead biochemical genetics laboratory to discuss. First line testing may include Gal-1-P, Galactitol or parental Galactose-1-phosphate uridyl transferase activities, depending on circumstances.


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