Prevalence
Mutations in TBC1D20 have been associated with Warburg micro syndrome, the prevalence of which is unknown, and Martsolf syndrome, which is characterized by similar, but milder clinical features.
Clinical characteristics
Warburg micro syndrome and Martsolf syndrome are characterized by abnormalities of the eyes, nervous system and endocrine system.
Inheritance
Both Warburg micro syndrome and Martsolf syndrome are transmitted as autosomal recessive traits
Molecular characteristics
Patients with Warburg micro syndrome and patients with Martsolf syndrome mutated in TBC1D20 have biallelic variants. To date, all TBC1D20 mutated cases have been reported having homozygous variants. These were found to include nonsense and frameshift variants, and multiexonic deletions.
Genetic Counselling
Syndromes associated with variants of TBC1D20 are inherited as an autosomal recessive trait. Therefore, at conception, each sibs of an affected individual has 25% risk of being affected, 50% risk of being a nonaffected carrier and 25% of being unaffected, therefore not a carrier.
Management
Treatment is symptomatic and supportive.