What is ALG12-CDG?

A form of congenital disorders of N-linked glycosylation characterized by facial dysmorphism (prominent forehead, large ears, thin upper lip), generalized hypotonia, feeding difficulties, moderate to severe developmental delay, progressive microcephaly, frequent upper respiratory tract infections due to impaired immunity with decreased immunoglobulin levels, and decreased coagulation factors. Additional features include hypogonadism with or without hypospadias in males, skeletal anomalies, seizures and cardiac anomalies in some cases. The disease is caused by loss of function mutations of the gene ALG12 (22q13.33).

Other condition names

  • CDG syndrome type Ig
  • CDG-Ig
  • CDG1G
  • Carbohydrate deficient glycoprotein syndrome type Ig
  • Congenital disorder of glycosylation type 1g
  • Congenital disorder of glycosylation type Ig
  • Mannosyltransferase 8 deficiency

Inheritance type

Autosomal recessive


  • Worldwide: <1 in 1,000 000

Age of Onset

  • Infancy
  • Neonatal
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