TBS and ZLS form a spectrum of disease. Features they have in common include hypoplasia or aplasia of the nails of the thumbs and great toes. Other nails may be hypoplastic as well. Gingival hypertrophy is common, although may not because apparent until later in life. TBS tends to have a more severe cerebral phenotype with profound developmental disability and a seizure disorder. In ZLS, intellect is usually mildly impaired, but has been reported as normal.
Both conditions have facial dysmorphia. In TBS, the face tends to be myopathic, whilst in ZLS facial features are coarsened. In addition, hirsutism and organomegaly are seen in ZLS.
KCNH1