Homozygous LZTR1 Variant Lacking the Second BTB Domain Associated With Bone Marrow Failure and Multiple Congenital Anomalies Distinct From Those of Noonan Syndrome

A homozygous LZTR1 frameshift variant resulting from maternal uniparental disomy of chromosome 22 [UPD(22)] is associated with bone marrow failure and dysmorphic features distinct from those of Noonan syndrome. Biallelic LZTR1 variants lacking the second BTB domain may underlie a rare clinical phenotype characterized by bone marrow failure.