Test for Unsaturated B12 Binding Capacity (UBBC)?

[theverytiredperson]

I'm in the UK and have read with interest a few posts on this forum about people who were given the UBBC blood test to identify whether issues with transcobalamin II are the cause of their B12 deficiency (I think that's how it has been used if I have understood it correctly). As someone with unexplained B12D who needs alternate day injections and has so far not tested positive for IF or parietal cell antibodies I am wondering if a UBBC test would help. Does anyone know if this is offered in the UK, and if so how I can get get it please?

[B12life]

I have this same question. Has anyone had this test and found it useful?

Unsaturated Vitamin B12 Binding Capacity

pubmed.ncbi.nlm.nih.gov/146...

"Results: Partial TC-II deficiency was found in 19 subjects. Apo TC-II (free TC-II unbound to vitamin B12) and total unsaturated B12 binding capacity were low in all tested individuals but one, and holo TC-II (TC-II bound by vitamin B12) was low in all family members. The presentation of the disease was chronic rather than acute. Early signs in children and young adults were dyslexia, decreased IQ, vertigo, plantar clonus and personality disorders. Interestingly, affected children and young adults had normal or slightly decreased serum vitamin B12 levels but were not anemic. Low serum B12 levels were measured in early adulthood. In mid-late adulthood megaloblastic anemia and subacute combined degeneration of the spinal cord were diagnosed. Treatment with B12 injections resulted in a significant improvement. The pedigree is compatible with an autosomal-dominant transmission. This family study suggests a genetic heterogeneity of TC-II deficiency.

Conclusions: We report the first family with a hereditary transmitted condition of low serum TC-II (partial TC-II deficiency) associated with neurologic and mental manifestations in childhood. Partial TC-II deficiency may decrease the amount of stored cobalamin, resulting in increased susceptibility to impaired intestinal delivery of cobalamin and predisposing to clinically expressed megaloblastic anemia at a later age. Partial TC-II deficiency should be suspected in families with megaloblastic anemia and in individuals with neurologic and mental disturbances--despite normal serum vitamin B12 levels. Low serum UBBC and apo TC-II should confirm the diagnosis. Early vitamin B12 therapy may prevent irreversible neurologic damage."