Expanding the clinical and molecular spectrum of NGLY1 deficiency: A multicenter cohort

NGLY1 deficiency is an ultra-rare multisystem disorder characterized by developmental delay, hyperkinetic movement disorder, hypo-/alacrimia, peripheral neuropathy, and elevated transaminases.

We conducted a multicenter retrospective study including 15 patients from 11 families to evaluate the clinical, biochemical, and molecular features of the disease. A literature review was also performed, and phenotypic data from published patients were evaluated.

All patients presented with developmental delay and dysmorphic facial features. Common neurological findings included abnormal EEG (10/15), seizures (9/15), hyperkinetic movement disorder (8/15), reduced deep tendon reflexes (6/15), and peripheral neuropathy (3/5). Frequent non-neurological features included feeding difficulties (9/15), scoliosis (7/13), hypo-/alacrimia (6/15), constipation (6/15), and auditory neuropathy (2/4). Peripheral and auditory neuropathy findings were observed over time. Elevated transaminases were the most common laboratory abnormality (12/14) and were transient in most patients (9/12), followed by low total cholesterol (7/10) and HDL levels (5/10). We identified 10 distinct variants, including two novel variants c.629delA (p.(Lys210SerfsTer14)) and c.1036C > T (p.(Gln346Ter)). Most patients carried homozygous variants, and no clear genotype-phenotype correlation was observed.

Our findings expand the clinical and molecular spectrum of NGLY1 deficiency and highlight its dynamic and progressive course, supporting the need for long-term clinical follow-up. NGLY1 deficiency may be considered in patients with neurologic findings and dysmorphic features, especially when transient elevated transaminases and hypolipidemia are also present.