hˌɪstɪdaɪnˈiːmiə ɪz kənsˈɪdɚd bᵻnˈaɪn æz mˈoʊst pˈeɪʃənts ɹᵻmˈeɪn ˌæsɪmptəmˈæɾɪk, ˈɜːli kˌɔɹɪlˈeɪʃənəl ˈɛvɪdəns fɹʌmðə fˈɜːst dˈɛkeɪd ʌv hˌɪstɪdaɪnˈiːmiə ɹᵻsˈɜːtʃ lˈiːd tə ðə θˈiəɹi ðæt hˌɪstɪdaɪnˈiːmiə wʌz ɐsˈoʊsɪˌeɪɾᵻd wɪð mˌʌltɪpəl dɪvˈɛləpmˈɛntəl sˈɪmptəmz ɪŋklˈuːdɪŋ hˌaɪpɚɹæktˈɪvᵻɾi, spˈiːtʃ ɪmpˈɛdɪmənt, dɪvˈɛləpmˈɛntəl dᵻlˈeɪ, lˈɜːnɪŋ dˈɪfɪkˌʌltiz, ænd sˈʌmtaɪmz mˈɛntəl ɹᵻɾɑːɹdˈeɪʃən.
Histidinemia is considered benign as most patients remain asymptomatic, early correlational evidence from the first decade of histidinemia research lead to the theory that histidinemia was associated with multiple developmental symptoms including hyperactivity, speech impediment, developmental delay, learning difficulties, and sometimes mental retardation.