Observations of the “isotopic anomaly” of positron (22Na) annihilation lifetime spectra in samples of gaseous neon of various isotopic abundance, the independent observations of the orthopositronium lifetime anomaly, and comparison of unique experimental data on the positron’s annihilation lifetime spectra in condensed deuterium (D2) and protium (H2), suggest a hypothesis on synthesis of 4He during the orthopositronium formation in deuterium. The decisive experiment is offered.