Chapter title |
Girls with Seizures Due to the c.320A>G Variant in ALG13 Do Not Show Abnormal Glycosylation Pattern on Standard Testing.
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Chapter number | 416 |
Book title |
JIMD Reports, Volume 22
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Published in |
JIMD Reports, March 2015
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DOI | 10.1007/8904_2015_416 |
Pubmed ID | |
Book ISBNs |
978-3-66-247452-5, 978-3-66-247453-2
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Authors |
Bethanny Smith-Packard, Scott M Myers, Marc S Williams, Scott M. Myers, Marc S. Williams, Smith-Packard, Bethanny, Myers, Scott M., Williams, Marc S. |
Abstract |
A girl with early onset severe epilepsy, developmental delay, intellectual disability, visual maturation delays, and feeding problems was without a diagnosis despite an extensive genetic and metabolic evaluation. She initially manifested infantile spasms which responded to high-dose ACTH. Seizures seemed to resolve, but then at age 5, she developed complex partial seizures resistant to antiepileptics that responded to a ketogenic diet. Additional features included visual impairment, hypotonia, reflux, and severe feeding problems requiring a G-tube. She was referred to the Geisinger Health System whole-genome sequencing clinical research program. A variant in the X-linked gene ALG13 (c.320A->G p. 107 N->S) was identified. Four additional girls from three published exome sequencing studies were found to have the identical c.320A>G variant in ALG13. All presented with early onset severe epilepsy and intellectual disability. Three of the five exhibited visual impairment and possible developmental regression. A boy with a variant in ALG13 presented with a severe congenital disorder of glycosylation type Is. Glycosylation studies in the case reported here were normal; none of the other girls reported in the literature have had glycosylation studies. X-inactivation studies have not been done. The N107 residue and the surrounding region - MNNHQ - are highly conserved across species and are found in a presumed functional domain of this glycotransferase superfamily. The consistent clinical presentation of a severe phenotype in girls coupled with identical variants in an X-linked gene strongly suggests a critical position effect. Negative glycosylation studies in one individual suggest the possibility of a new mechanism requiring investigation. |
X Demographics
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Unknown | 2 | 100% |
Demographic breakdown
Type | Count | As % |
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Practitioners (doctors, other healthcare professionals) | 2 | 100% |
Mendeley readers
Geographical breakdown
Country | Count | As % |
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Unknown | 25 | 100% |
Demographic breakdown
Readers by professional status | Count | As % |
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Student > Bachelor | 6 | 24% |
Student > Ph. D. Student | 4 | 16% |
Other | 3 | 12% |
Student > Master | 2 | 8% |
Student > Doctoral Student | 1 | 4% |
Other | 3 | 12% |
Unknown | 6 | 24% |
Readers by discipline | Count | As % |
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Biochemistry, Genetics and Molecular Biology | 5 | 20% |
Medicine and Dentistry | 4 | 16% |
Agricultural and Biological Sciences | 3 | 12% |
Neuroscience | 3 | 12% |
Economics, Econometrics and Finance | 1 | 4% |
Other | 1 | 4% |
Unknown | 8 | 32% |