The 5q- syndrome is a myelodysplastic syndrome characterized by a defect in erythroid differentiation. Patients have severe macrocytic anemia, normal or elevated platelet counts, normal or reduced neutrophil counts, erythroid hypoplasia in the bone marrow, and hypolobated micromegakaryocytes (Ebert et al., 2008).

This primary immunodeficiency, designated IMD21, DCML, or MONOMAC, is characterized by profoundly decreased or absent monocytes, B lymphocytes, natural killer (NK) lymphocytes, and circulating and tissue dendritic cells (DCs), with little or no effect on T-cell numbers. Clinical features of IMD21 are variable and include susceptibility to disseminated nontuberculous mycobacterial infections, papillomavirus infections, opportunistic fungal infections, and pulmonary alveolar proteinosis. Bone marrow hypocellularity and dysplasia of myeloid, erythroid, and megakaryocytic lineages are present in most patients, as are karyotypic abnormalities, including monosomy 7 and trisomy 8. In the absence of cytogenetic abnormalities or overt dysplasia, hypoplastic bone marrow may initially be diagnosed as aplastic anemia. Bone marrow transplantation is the only cure. Some patients may have an increased risk of miscarriage. Both autosomal dominant transmission and sporadic cases occur. Less common manifestations of GATA2 deficiency include lymphedema and sensorineural hearing loss, a phenotype usually termed 'Emberger syndrome' (614038) (summary by Bigley et al. (2011), Hsu et al. (2011), and Spinner et al. (2014)).

Syndromic thrombocytopenia-13 (THC13) is an autosomal recessive disorder characterized mainly by congenital thrombocytopenia resulting in increased bleeding. Platelets tend to be enlarged (macrothrombocytopenia) and/or gray and show functional defects. Some patients have infection-induced leukopenia or anemia and pancytopenia. Additional more variable features have also been reported, including mitral valve malformations, pyloric stenosis, and impaired intellectual development (Seo et al., 2019; Febres-Aldana et al., 2020; Marin-Quilez et al., 2023). For a discussion of genetic heterogeneity of thrombocytopenia, see THC1 (313900).