PGM1-CDG

PGM1-CDG (primary dysglycosylation disorder type 1a) is a rare inherited disorder that belongs to the group of protein and lipid glycosylation disorders. It occurs due to a defect in the glycosylation process, which leads to abnormal formation of glycoproteins and glycolipids. PGM1-CDG is caused by mutations in the PMM2 gene, which encodes the enzyme phosphomonosylpentose, which is involved in biosynthetic pathways. The disease manifests itself as a result of the accumulation of incomplete or incorrectly modified glycoproteins in cells, which can lead to multiple systemic disorders, including developmental delay, neurological disorders, liver and immune system problems, and various abnormalities in organs and systems. The clinical manifestations of PGM1-CDG are extremely diverse, which complicates early diagnosis and determination of the correct treatment strategy.

History of the disease and interesting historical facts

PGM1-CDG was first described in the literature in 1999, but diseases caused by glycosylation disorders have been studied since the early 1980s. Initially, attention was drawn to diseases such as Werlhof's syndrome and other autosomal recessive disorders. Experimental studies and observations of patients with clinical manifestations similar to PGM1-CDG syndrome allowed us to compile the first understanding of the pathogenesis and etiology of the disease. In 2016, a study published in the journal Genetics in Medicine examined various aspects of PGM1-CDG, which served as a basis for in-depth study and improved diagnostics.

Epidemiology

PGM1-CDG is a rare disease that occurs worldwide with an estimated incidence of 1 in 100,000-1,000,000 live births. In some populations, such as Finland, the incidence is significantly higher, reaching 1 in 10,000 live births. There is also evidence of low incidence in some ethnic groups, which may be due to genetic factors and reproductive habits. An important aspect is that as prenatal diagnosis becomes more widespread, the incidence of the disease increases, which may affect the statistics.

Genetic predisposition to this disease

PGM1-CDG is associated with mutations in the PMM2 gene located on chromosome 16. This gene encodes the enzyme phosphomonosylpentose, which is necessary for the proper synthesis of glycoproteins. More than 200 different mutations of this gene have been described and classified by their pathogenicity. The most common mutation is c.563A>C (p.N188T), which occurs in the majority of patients with PGM1-CDG. Interestingly, many mutations in PMM2 result in varying degrees of clinical symptoms, different severity of the disease, which indicates the presence of genetic heterogeneity.

Risk factors for the development of this disease

PGM1-CDG is transmitted in an autosomal recessive manner. This means that two mutant copies of the PMM2 gene, one from each parent, are required for the disease to manifest. Thus, risk factors include:

• Presence of ancestors with mutations in the PMM2 gene.
• Marriages between close relatives, which increases the likelihood of inheriting similar mutations.
• Genetic predisposition in certain ethnic groups.
• Low awareness of genetic aspects of diseases in different regions.

Diagnosis of this disease

PGM1-CDG can be diagnosed based on a combination of clinical symptoms and laboratory tests. The main symptoms include:

• Developmental delay and mental retardation.
• Liver problems, including liver failure.
• Neurological disorders such as epilepsy.
• Immunodeficiency states.

Laboratory tests to confirm the diagnosis include:

• Measurement of serum transferrin levels.
• Determination of cross-sections of the structures of glycoproteins and lipids.
• Genetic testing to detect mutations in the PMM2 gene.

Radiologic studies may include magnetic resonance imaging to evaluate the brain. Differential diagnosis should include other metabolic disorders and genetic diseases such as Crouzon syndrome and other syndromes associated with glycosylation disorders.

Treatment

Currently, there is symptomatic treatment for PGM1-CDG aimed at alleviating the conditions associated with the disease. The main approaches to treatment include:

• General treatment is supportive care, including regular monitoring of the patient's progress.
• Pharmacological treatment is aimed at controlling symptoms such as epilepsy and liver failure.
• Surgery may be recommended for certain complications, such as severe liver problems.
• Probiotics and prebiotic supplements can be used to support digestive function.

Since treatment of PGM1-CDG is still in the research phase, it is necessary to constantly update information on new therapeutic approaches.

List of medications used to treat this disease

Important medications used in the treatment of patients with PGM1-CDG may include:

• Antiepileptic drugs (eg, valproic acid).
• Hepatoprotectors (eg, essential phospholipids).
• Existing drugs for correcting nutritional deficiencies.

Disease monitoring

Monitoring of patients with PGM1-CDG includes regular control examinations to assess the health status, functional status of organs and systems. The main control stages are:

• Laboratory tests to evaluate liver function and transferrin levels.
• Assessment of intellectual and physical development.
• Assessment of neurological functions for early detection of complications such as epilepsy.

The prognosis for patients with PGM1-CDG depends on the severity of the mutations and clinical manifestations. Complications may include the development of severe neurological disorders and liver failure, which can be life-threatening.

Age-related features of the disease

PGM1-CDG may present at any age, but the severity of symptoms and disease progression may vary. Newborns may have more severe manifestations, while older patients may have milder symptoms. In clinical practice, there are cases where a mild form of the disease may not be detected until adolescence or later.

Questions and Answers

• What is PGM1-CDG? PGM1-CDG is an inherited glycosylation disorder caused by mutations in the PMM2 gene.
• What are the main symptoms of PGM1-CDG? The main symptoms include developmental delays, neurological disorders, liver problems and immune system problems.
• How is PGM1-CDG diagnosed? Diagnosis is based on clinical symptoms and laboratory tests, including blood tests for transferrin and genetic testing.
• How is PGM1-CDG treated? Treatment is primarily symptomatic and includes supportive care and drug treatment of symptoms.
• What is the prognosis for patients with PGM1-CDG? The prognosis depends on the severity of the mutation and clinical manifestations; serious complications are possible and require constant monitoring.