Objective:To evaluate the phenotypic spectrum associated with mutations in TBC1D24.Methods:We acquired new clinical, EEG, and neuroimaging data of 11 previously unreported and 37 published patients. TBC1D24 mutations, identified through various sequencing methods, can be found online (http://lovd.nl/TBC1D24).Results:Forty-eight patients were included (28 men, 20 women, average age 21 years) from 30 independent families. Eighteen patients (38%) had myoclonic epilepsies. The other patients carried diagnoses of focal (25%), multifocal (2%), generalized (4%), and unclassified epilepsy (6%), and early-onset epileptic encephalopathy (25%). Most patients had drug-resistant epilepsy. We detail EEG, neuroimaging, developmental, and cognitive features, treatment responsiveness, and physical examination. In silico evaluation revealed 7 different highly conserved motifs, with the most common pathogenic mutation located in the first. Neuronal outgrowth assays showed that some TBC1D24 mutations, associated with the most severe TBC1D24-associated disorders, are not necessarily the most disruptive to this gene function.Conclusions:TBC1D24-related epilepsy syndromes show marked phenotypic pleiotropy, with multisystem involvement and severity spectrum ranging from isolated deafness (not studied here), benign myoclonic epilepsy restricted to childhood with complete seizure control and normal intellect, to early-onset epileptic encephalopathy with severe developmental delay and early death. There is no distinct correlation with mutation type or location yet, but patterns are emerging. Given the phenotypic breadth observed, TBC1D24 mutation screening is indicated in a wide variety of epilepsies. A TBC1D24 consortium was formed to develop further research on this gene and its associated phenotypes.

In our study, almost 80% of the fetuses had an uncomplicated perinatal outcome. FEB was present as the only finding in only 5% of the fetuses with an adverse outcome. A potential association with placental abnormalities and a low prevalence of viral infections was observed. These findings may be of use in counseling parents.

Non-invasive prenatal testing (NIPT), is a prenatal screening test for chromosomal aneuploidies (trisomy 21, trisomy 18, and trisomy 13). While women under 35 years of age with no other risk factors are considered low risk for pregnancies with aneuploidy, most babies with aneuploidy are born to low-risk women. Across the USA, including Wisconsin, many private insurances do not cover initial NIPT for low-risk women, creating a potential financial burden that may limit patient selection of NIPT. Low-risk women with public insurance in Wisconsin are covered for NIPT. This pilot study determined if a difference exists in NIPT uptake based on insurance type in low-risk pregnant women in their first trimester. It also explored genetic counselor perspectives on how insurance coverage for NIPT is addressed with patients. Women with public insurance were 3.43 times more likely to have NIPT as an initial screen for aneuploidy than women with private insurance, indicating that insurance coverage may present a barrier to care. Additionally, analysis showed no evidence of different demographic variables interacting with another to impact outcome after allowing for insurance coverage (X 2 14 = 14.301, p = 0.428). Our data also suggests that more genetic counselors would recommend NIPT to patients if insurance coverage was not a barrier and were more likely to discuss financial risks associated with NIPT when a patient had private insurance. We conclude that some women cannot choose one of the safest and most sensitive prenatal aneuploidy screening tests due to financial barriers put into place by the lack of insurance coverage.