Congenital betalipoprotein deficiency syndrome

=Congenital Betalipoprotein Deficiency Syndrome = Congenital Betalipoprotein Deficiency Syndrome, also known as Abetalipoproteinemia, is a rare genetic disorder that affects the absorption of dietary fats, cholesterol, and fat-soluble vitamins. This condition is characterized by the absence or severe reduction of betalipoproteins in the blood.

Etiology

The syndrome is caused by mutations in the MTTP gene, which encodes the microsomal triglyceride transfer protein. This protein is essential for the assembly and secretion of apolipoprotein B-containing lipoproteins in the liver and intestine.

Pathophysiology

In individuals with Congenital Betalipoprotein Deficiency Syndrome, the lack of functional microsomal triglyceride transfer protein leads to the inability to form chylomicrons and very low-density lipoproteins (VLDL). This results in malabsorption of dietary fats and fat-soluble vitamins, leading to a variety of systemic effects.

Clinical Features

Patients with this syndrome typically present with:

• Steatorrhea (fatty stools) due to malabsorption of fats.
• Failure to thrive in infancy.
• Neurological symptoms such as ataxia and peripheral neuropathy due to vitamin E deficiency.
• Retinitis pigmentosa, which can lead to vision loss.

Diagnosis

Diagnosis is based on clinical presentation, laboratory findings, and genetic testing. Key laboratory findings include:

• Low levels of cholesterol and triglycerides in the blood.
• Absence of apolipoprotein B-containing lipoproteins.
• Genetic testing confirming mutations in the MTTP gene.

Treatment

Management of Congenital Betalipoprotein Deficiency Syndrome involves:

• Dietary modifications to include medium-chain triglycerides, which do not require chylomicron formation for absorption.
• Supplementation with fat-soluble vitamins, particularly vitamin E, to prevent neurological complications.
• Regular monitoring and supportive care to manage symptoms and prevent complications.

Prognosis

With early diagnosis and appropriate management, individuals with Congenital Betalipoprotein Deficiency Syndrome can have a significantly improved quality of life. However, untreated vitamin deficiencies can lead to irreversible neurological damage and other complications.

See Also

• Hypobetalipoproteinemia
• Familial Abetalipoproteinemia

NIH genetic and rare disease info

• NIH info on Congenital betalipoprotein deficiency syndrome

Congenital betalipoprotein deficiency syndrome is a rare disease.