Diagnostic exome sequencing for patients with a family history of consanguinity: over 38% of positive results are not autosomal recessive pattern.

Diagnostic exome sequencing (DES) is an effective tool for diagnosis in intractable cases where the underlying cause is thought be genetic. It is commonly assumed that patients with a family history of consanguinity will have increased detection rates for rare autosomal recessive Mendelian disorders through DES. Herein, we analyzed the diagnostic yield and relevant inheritance patterns within the DES cases with a reported consanguineous family history. Of the first 500 unselected cases referred for DES, 40 (8.0%) had a known consanguineous family history. Among the 40 cases, 13 (32.5%) received a definitive molecular diagnosis through DES and such positive rate is similar to that of families with no reported consanguinity (139/460, 30.2%, P=0.63). Although homozygous alterations likely related to consanguinity have been identified in eight positive cases, the other five (38.4%) causative mutations were unrelated to autosomal recessive inheritance. Our retrospective analysis demonstrated that individuals with known consanguinity were not more likely to have a positive DES result and a significant portion of the positive findings were not within an autosomal recessive gene. These results highlight that all applicable inheritance patterns should be considered for patients with a known family history of consanguinity.