Hay fever in Japan is caused primarily by sugi (Cryptomeria japonica) and hinoki (Chamaecyparis obtusa) tree pollen. "Allergy friendly" trees include: female ash, red maple, yellow poplar, dogwood, magnolia, double-flowered cherry, fir, spruce, and flowering plum. Grasses (Family Poaceae): especially ryegrass (Lolium sp.) and timothy (Phleum pratense). An estimated 90% of people with hay fever are allergic to grass pollen. Weeds: ragweed (Ambrosia), plantain (Plantago), nettle/parietaria (Urticaceae), mugwort (Artemisia Vulgaris), Fat hen (Chenopodium), and sorrel/dock (Rumex)Allergic rhinitis may also be caused by allergy to Balsam of Peru, which is in various fragrances and other products. Genetic factors
The causes and pathogenesis of allergic rhinitis are hypothesized to be affected by both genetic and environmental factors, with many recent studies focusing on specific loci that could be potential therapeutic targets for the disease. Genome-wide association studies (GWAS) have identified a number of different loci and genetic pathways that seem to mediate the bodys response to allergens and promote the development of allergic rhinitis, with some of the most promising results coming from studies involving single-nucleotide polymorphisms (SNPs) in the interleukin-33 (IL-33) gene. The IL-33 protein that is encoded by the IL-33 gene is part of the interleukin family of cytokines that interact with T-helper 2 (Th2) cells, a specific type of T cell. Th2 cells contribute to the bodys inflammatory response to allergens, and specific ST2 receptors, also known as IL1RL1,  on these cells bind to the ligand IL-33 protein.
Amino acid transport disorders are medical conditions associated with a failure of amino acids to be absorbed from the kidney or intestine. An example is Hartnup disease. Reference
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Milne MD (1971). "Disorders of intestinal amino-acid transport". J Clin Pathol. 5 (Suppl): 41–4. doi:10.1136/jcp.s3-5.1.41. PMC 1176258.