NGLY1 deficiency

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
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NGLY1 deficiency
Protein NGLY1 PDB 2ccq
Synonyms	Congenital disorder of deglycosylation
Pronounce
Specialty	Medical genetics
Symptoms	Developmental delay, movement disorders, liver dysfunction, seizures
Complications	N/A
Onset	Infancy
Duration	Lifelong
Types	N/A
Causes	Mutations in the NGLY1 gene
Risks
Diagnosis	Genetic testing, clinical evaluation
Differential diagnosis	Other congenital disorders of glycosylation
Prevention	None
Treatment	Supportive care, physical therapy
Medication
Prognosis	Variable
Frequency	Very rare
Deaths

NGLY1 deficiency is a rare genetic disorder caused by mutations in the NGLY1 gene, which encodes the enzyme N-glycanase 1. This enzyme is responsible for the deglycosylation of misfolded glycoproteins in the endoplasmic reticulum-associated degradation (ERAD) pathway. The deficiency leads to a buildup of misfolded glycoproteins, resulting in a variety of clinical symptoms.

Clinical Features

Patients with NGLY1 deficiency typically present with a range of symptoms, including:

• Developmental delay
• Hypotonia
• Seizures
• Liver dysfunction
• Movement disorders
• Alacrima (reduced tear production)

The severity and combination of symptoms can vary widely among affected individuals.

Genetics

NGLY1 deficiency is inherited in an autosomal recessive manner. This means that an affected individual must inherit two copies of the mutated gene, one from each parent. Carriers, who have only one copy of the mutation, typically do not show symptoms.

Pathophysiology

The NGLY1 enzyme plays a crucial role in the ERAD pathway by removing N-linked glycans from misfolded glycoproteins, allowing them to be degraded by the proteasome. In the absence of functional NGLY1, these glycoproteins accumulate, leading to cellular stress and dysfunction.

Diagnosis

Diagnosis of NGLY1 deficiency is typically confirmed through genetic testing, which identifies mutations in the NGLY1 gene. Biochemical assays may also be used to assess enzyme activity.

Management

Currently, there is no cure for NGLY1 deficiency. Management focuses on symptomatic treatment and supportive care, which may include:

• Physical therapy for motor skills
• Anticonvulsants for seizure control
• Nutritional support
• Management of liver dysfunction

Research

Research into NGLY1 deficiency is ongoing, with efforts focused on understanding the molecular mechanisms of the disease and developing potential therapies. Gene therapy and enzyme replacement therapy are areas of active investigation.

See also

• Genetic disorders
• Endoplasmic reticulum-associated degradation
• Autosomal recessive inheritance