Interestingly, cell lines overexpressing LETM1 harboring a deleted EF-hand or the D676A/D687K mutation within the Ca2+ binding EF-hand loop (i.e., loop residues 676–687; Figure 1 and Figure 3) as well as fibroblasts derived from WHS patients (see below) who are haploinsufficient in LETM1, all showed impaired Ca2+ transport. The gene discussed is LETM1; the disease is Wolf-Hirschhorn syndrome.