To illustrate the challenge of diagnosing biallelic BBS1 variants, even when one copy is the common founder missense variant NM_024649.5:c.1169T>G, NP_078925.3:p.(Met390Arg), we further reviewed the ‘Congenital Malformations caused by Ciliopathies’ (CMC) cohort, as described previously,13 for potential compound heterozygous BBS1 variants. The gene discussed is BBS1; the disease is pregnancy disorder.