Pathogenic ATM variation causes ataxia-telangiectasia in an autosomal recessive manner but the patient’s exome data did not reveal a second trans variant in ATM. RNA sequencing of the patient’s fibroblasts identified reciprocal ATM-SLC35F2 and SLC35F2-ATM fusion transcripts suggesting chromosomal inversion that was later confirmed by targeted long-read sequencing of the putatively affected introns [136]. The gene discussed is SLC35F2; the disease is Ataxia-telangiectasia.