Predominant and novel de novo variants in 29 individuals with ALG13 deficiency: Clinical description, biomarker status, biochemical analysis, and treatment suggestions.

Asparagine-linked glycosylation 13 homolog (ALG13) encodes a nonredundant, highly conserved, X-linked uridine diphosphate (UDP)-N-acetylglucosaminyltransferase required for the synthesis of lipid linked oligosaccharide precursor and proper N-linked glycosylation. De novo variants in ALG13 underlie a form of early infantile epileptic encephalopathy known as EIEE36, but given its essential role in glycosylation, it is also considered a congenital disorder of glycosylation (CDG), ALG13-CDG. Twenty-four previously reported ALG13-CDG cases had de novo variants, but surprisingly, unlike most forms of CDG, ALG13-CDG did not show the anticipated glycosylation defects, typically detected by altered transferrin glycosylation. Structural homology modeling of two recurrent de novo variants, p.A81T and p.N107S, suggests both are likely to impact the function of ALG13. Using a corresponding ALG13-deficient yeast strain, we show that expressing yeast ALG13 with either of the highly conserved hotspot variants rescues the observed growth defect, but not its glycosylation abnormality. We present molecular and clinical data on 29 previously unreported individuals with de novo variants in ALG13. This more than doubles the number of known cases. A key finding is that a vast majority of the individuals presents with West syndrome, a feature shared with other CDG types. Among these, the initial epileptic spasms best responded to adrenocorticotropic hormone or prednisolone, while clobazam and felbamate showed promise for continued epilepsy treatment. A ketogenic diet seems to play an important role in the treatment of these individuals.

Beyond circles and squares: A commentary on updating pedigree nomenclature to better represent patient diversity.

With changes in our understanding of gender identity and disorders of sex differentiation (DSDs), as well as a need to promote medical care that appropriately reflects the intersectional personal identities of patients with respect to sex and gender, we explored possible modifications of pedigree nomenclature to better represent such patient diversity. There are currently no widely accepted standard symbols to simultaneously represent both gender identity and assigned sex at birth within a pedigree. Previous studies assessing perspectives from members of the transgender and gender non-binary (TGNB) community have highlighted the need for a unique symbol to represent non-binary individuals and better ways to represent core gender identities for gender minorities such as transgender individuals. In our experience we have encountered similar dilemmas with documentation for individuals with DSDs in terms of a lack of unequivocal symbolic representation within the pedigree. Here we propose three distinct symbols for gender identity combined with superscript symbols to represent sex assigned at birth, which we think may unequivocally represent TGNB individuals and patients with DSDs. It is clear that further research is needed to ensure that any proposed changes are acceptable by and respectful of all patients regardless of their gender identity and assigned sex at birth. We hope that further research will include focus groups and surveys to get broader input from gender minority stakeholders so that new standards can be developed and modified as we strive to meet the needs of our increasingly diverse patient population.