Recently, several individuals with a specific syndromic neurodevelopmental disorder were found to have bi-allelic mutations in the human TAN1 ortholog THUMPD1, which was linked to complete loss of ac4C in small RNA and in purified tRNASer(CGA) for one set of derived lymphoblastoid cell lines, and for each of two human KO cell lines [37]. The gene discussed is THUMPD1; the disease is neurodevelopmental disorder.