“… Note : ↓, decrease; ↑, increase; =, remained stable. References: 1, (Reid & Aungle, 1974 ); 2, (Day, 1985 ); 3, (Evenhuis, 1990 ); 4, (Duggan et al, 1996 ); 5, (Burt et al, 1998 ); 6, (Määttä et al, 2006 ); 7, (Margallo‐Lana et al, 2007 ); 8, (Sauna‐Aho et al, 2018 ); 9, (Haveman et al, 1994 ); 10, (Cherry et al, 1997 ); 11, (Rousseau et al, 2019 ). Abbreviations: DS, Down syndrome; non‐DS, without Down syndrome; PID, profound intellectual disabilities.…”