The now 26-year-old patient [case #17; Table 2 in our previous publication ] is the son of consanguineous Pakistani parents, who were healthy and had normal blood counts. One sister was healthy, a second sister suffered from hepatitis C, but had normal blood counts. He had been prone to infections, primarily recurrent bronchitis, since birth and was first seen in our clinic when he was five and a half years old with fever and coughing. He was growth retarded and had a microcephaly (<3rd percentile), clinodactyly of both hands and hyperpigmented skin above the knees and elbows. Apart from his microcephaly, imaging of the head, the thorax and the abdomen remained inconspicuous. Screening for causative infectious agents, including Mycobacterium tuberculosis, was unrewarding. Immunological analyses that were performed during the course of the disease revealed IgA deficiency and B-lymphocytopenia (Details are provided in  Supplementary Table 1 ). Hematologic analysis at first presentation revealed a white blood cell count of 1.47 x109/L with an absolute neutrophil count of 0.76 x109/L and an absolute lymphocyte count of 0.47 x109/L, a hemoglobin level of 9.2 g/dL, MCV of 75fl, and a platelet count of 109 x109/L. Data on the long-term course of hematological parameters are provided in  Supplementary Figure 1 . A bone marrow (BM) examination disclosed reduced cellularity of all three lineages with an erythropoiesis-restricted dysplasia that, together with the presence of a fluorescence in situ hybridization (FISH)-verified monosomy 7 in 18% of the analyzed nuclei, was consistent with the diagnosis of a hypocellular myelodysplastic syndrome in form of a refractory cytopenia. Although the appearance of monosomy 7 in IBMF is strongly indicative of an underlying SAMD9/9L or GATA2 deficiency, these disease-promoting germline causes were not known at that time.