"low B12 serum B12 incidence is 22.3% incidence" uhhh well i really should proof read my answers lol.
Most of your symptoms are listed under vitamin B12 deficiency - memory loss (B12 deficiency can be misdiagnosed as Alzheimer's disease, permanent dementia if not treated in time), fatigue, impaired sense of smell, low blood pressure, depression, intermittent constipation and diarrhea, dizziness/vertigo, easy bruising if blood cells are enlarged or due to iron anaemia (B12 deficiency is a listed cause of iron deficiency). Optimal B12 serum levels are over 800pg/mL. That said, some of these symptoms can be seen in other conditions. One condition i came across is Gaucher's Disease.
I found one study that stated low B12 serum B12 incidence is 22.3% incidence among Ashkenazi Jews and 40% among patients with Gaucher disease. Gaucher disease type 1 is stated to be common among Ashkenazi Jews; carrier frequency is 1 in 7.
Major signs and symptoms of Gaucher disease include enlargement of the liver and spleen (hepatosplenomegaly), a low number of red blood cells (anaemia), easy bruising caused by a decrease in blood platelets (thrombocytopenia), lung disease, and bone abnormalities such as bone pain, fractures, and arthritis. Many with Gaucher disease have a mild form of the disease or may not show any symptoms at all.