Hence, we quantified transcription of TRIM43 and MBD3L2. We found that both these genes are upregulated in the patient as compared to unaffected controls (S3 Fig), indicating that DUX4 protein may be expressed in the ICF1 patient but not in the mother who has a 4qA allele but does not possess a hypomethylated D4Z4. This evidence concerns the gene TRIM43 and immunodeficiency-centromeric instability-facial anomalies syndrome 1.