Features include always present findings: Increased RBC distribution width, Low red blood cell count (anemia), Elevated LDH (tissue damage marker) (increased circulating lactate dehydrogenase concentration), and Increased immature red blood cells (reticulocytosis) and others; and common findings: Short stature, Wide anterior fontanel, Enlarged liver (hepatomegaly), and Erythroid hyperplasia and others. 29 total HPO annotations.

KLF1 encodes KLF transcription factor 1 (362 aa). Transcription regulator of erythrocyte development that probably serves as a general switch factor during erythropoiesis. Is a dual regulator of fetal-to-adult globin switching. Highest expression in Whole Blood (21.6 TPM) and Spleen (1.4 TPM).

Congenital dyserythropoietic anemia type 4 is associated with mutations in the KLF1 gene on chromosome 19.

The KLF1 protein participates in Expression of KLF15, GATA3, CHD4, EP300, NFATC2 (NFAT1), FOS:JUN (AP-1), KLF13, and MAF bind the IL4 gene, and GATA3, CHD4, EP300, NFATC2 (NFAT1), FOS:JUN (AP-1), KLF13, MAF, YY1, ETS1, POU2F1 (OCT1), POU2F2 (OCT2), BATF, SATB1, IRF4, SMARCA4, and STAT6 positively regulate expression of IL4 pathways.

KLF1 is classified as a druggable target (Transcription Factor category) with score 0.0.

Genetic testing for KLF1 is available. Testing is considered confirmatory for diagnosis.

Phenotype severity distribution: 15 always present features, 12 common features.

Estimated prevalence: <1 in 1,000,000 (VERY_RARE).