Serum Vit B12 within normal limits; Erythrocyte folate: normal. LDH: elevated.
Cytogenetics: 46 XY, FISH analysis is negative for -5/5q-, -7/7q-, +8, and -20/20q-.
NGS exome sequencing:
This patient is heterozygous in the TCN2 gene for two variants, a pathogenic deletion and one non-sense mutation, c/w Transcobalamin II deficiency.
Diagnosis:
Transcobalamin II deficiency.
Cytogenetics: 46 XY, FISH analysis is negative for -5/5q-, -7/7q-, +8, and -20/20q-.
NGS exome sequencing:
This patient is heterozygous in the TCN2 gene for two variants, a pathogenic deletion and one non-sense mutation, c/w Transcobalamin II deficiency.
Diagnosis:
Transcobalamin II deficiency.
http://veganhealth.org/b12/dig
Transcobalamin II (TCII) deficiency is an autosomal recessive disease marked by defective intestinal absorption of vitamin B12. It is caused by variants in TCN2 gene (22q12.2), which lead to non-specific symptoms in infants (e.g. vomiting, poor growth) and infections due to an immune deficiency (hypogammaglobulinemia). The main symptom is megaloblastic anemia. Serum cobalamin level is within normal limits since the major circulating form, methyl vitamin B12, is bound to another transport protein (transcolabamin I). Early vitamin B12 therapy may result in complete resolution of symptoms, except when the diagnosis is delayed and neurological signs have become permanent.