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Carbohydrate-deficient glycoprotein syndrome--a fourth subtype
H Stibler1, U Stephani, U Kutsch
1Department of Neurology, Karolinska Hospital, Stockholm, Sweden.
Insights
This study identifies a potential new subtype of carbohydrate-deficient glycoprotein (CDG) syndrome in two infants. The condition presents with microcephaly, severe epilepsy, and distinct glycoprotein abnormalities, differing from known CDG types.
Area of Science:
- Biochemistry
- Genetics
- Pediatrics
Background:
- Carbohydrate-deficient glycoprotein (CDG) syndromes are a group of rare inherited metabolic disorders.
- These disorders result from defects in the synthesis of glycans (carbohydrate chains) that are attached to proteins.
- CDG syndromes exhibit a wide range of clinical manifestations, affecting multiple organ systems.
Observation:
- Two infants presented with microcephaly, severe epilepsy, absent psychomotor development, and minor dysmorphic features.
- No signs of liver dysfunction were observed in either patient.
- Analysis of blood glycoproteins revealed abnormal isoforms, indicating a partial deficiency in sialic acid residues.
Findings:
- The observed clinical and biochemical profiles suggest a novel, fourth subtype of CDG syndrome.
- Specific glycoproteins, including transferrin, alpha 1-antitrypsin, antithrombin, and thyroxine-binding globulin, showed abnormal glycosylation patterns.
- The identified abnormalities in sialic acid residues were distinct from those seen in previously characterized CDG types.
Implications:
- This discovery expands the known spectrum of CDG syndromes.
- Further research is needed to elucidate the specific genetic basis and pathophysiology of this potential new subtype.
- Accurate diagnosis and understanding of this subtype are crucial for potential future therapeutic strategies and genetic counseling.
Abstract:
Two infants are described, who, we suggest, represent a fourth subtype of carbohydrate-deficient glycoprotein (CDG) syndrome. Both patients showed microcephaly and severe epilepsy with absent psychomotor development and similar minor dysmorphic features. There were no signs of liver dysfunction. Several glycoproteins in blood, including transferrin, alpha 1-antitrypsin, antithrombin and thyroxine-binding globulin, demonstrated abnormal isoforms suggesting a partial deficiency of mainly one or two sialic acid residues. Both the clinical picture and the glycoprotein abnormalities were different from previously defined types of CDG syndrome.