How to map presence of alleles to LOINC

Implementers
1

Help! We’re trying to map the following information to the CDM (LOINC):

We have a genetic test showing whether someone is carrying ApoE4, either homozygous or heterozygous.

There are two relevant LOINC codes as far as we can see:
15353-6 Apolipoprotein E-IV [Presence] in Blood
34735-1 APOE gene allele 4 [Identifier] in Blood or Tissue by Molecular genetics method Nominal

My guess is we’d need the second concept, with nominal values ‘Absent’, ‘Homozygote’, ‘Heterozygote’. We do have such concepts in SNOMED:
Concept_id Concept_name Concept_class Concept_code Domain_id
4132135 Absent Qualifier value 2667000 Meas Value
4031674 Heterozygote Qualifier value 14556007 Observation
4329704 Homozygote Clinical finding 22061001 Condition

However, as you can see, none of these are of the domain ‘Meas value’. I’m not sure how these SNOMED concepts are normally used. Any ideas?

2

Martijn:

2 answers:

  1. The first of the two LOINC codes is probably not what you want. It’s the precence of the lipoprotein, not the gene on the DNA. So, pick the second.
  2. You are totally right. We do have a problem with the overlap between the Observation and Measurement Domains. But because the Observation is always a lower precedence, we will turn these into Meas Value. I’ll make those changes.

Keep it coming.
C

3

Thanks!