Complex sentence: Some children with autoimmune lymphoproliferative disorders are heterozygous for a mutation in the gene that codes for the Fas receptor, which is located on the long arm of chromosome 10 at position 24.1, denoted 10q24.1.
Split into simpler sentences: Some children with autoimmune lymphoproliferative disorders are heterozygous for a mutation in the gene that codes for the Fas receptor. Which is located on the long arm of chromosome 10 at position 24.1, denoted 10q24.1.