Megaloblastic Anemia 1

Alternative Names

  • MGA1
  • Imerslund-Grasbeck Syndrome
  • IGS
  • Pernicious Anemia, Juvenile, due to Selective Intestinal Malabsorption of Vitamin B12, with Proteinuria
  • Enterocyte Cobalamin Malabsorption Enterocyte Intrinsic Factor Receptor, Defect of

Associated Genes

Cubilin
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WHO-ICD-10 version:2010

Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism

Nutritional anaemias

OMIM Number

261100

Mode of Inheritance

Autosomal recessive

Gene Map Locus

10p13,14q32.32

Description

Megaloblastic anemia is a hematological disorder in which the bone marrow produces abnormally large nucleated cells, including immature erythrocytes, superlobulated polymorphic leukocytes and large platelets. At the cellular level, megaloblastic anemia 1 (MGA1), originally named Imerslund-Grasbeck syndrome (IGS), is caused by intestinal malabsorption of vitamin B12 (cobalamin) due to a defect in the vitamin B12/gastric intrinsic factor (GIF) complex receptor. Clinically, IGS is characterized by relatively early childhood onset (before age 5 years), failure to thrive, infections, low level of vitamin B12 in serum, mild and innocuous proteinuria, and variable neurological symptoms such as peripheral neuropathy, cognitive problems, and dementia.

Epidemiology in the Arab World

View Map
Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
261100.1.1Saudi ArabiaMaleYesYes Megaloblastic anemiaNM_001081.3:c.434G>AHomozygousAutosomal, RecessiveTanner et al. 2004
261100.1.2Saudi ArabiaMaleYesYes Megaloblastic anemiaNM_001081.3:c.434G>AHomozygousAutosomal, RecessiveTanner et al. 2004 Brother of 261100.1....
261100.1.3Saudi ArabiaMaleYesYes Megaloblastic anemiaNM_001081.3:c.434G>AHomozygousAutosomal, RecessiveTanner et al. 2004 First cousin of 2611...
261100.1.4Saudi ArabiaMaleYesYes Megaloblastic anemiaNM_001081.3:c.434G>AHomozygousAutosomal, RecessiveTanner et al. 2004 First cousin of 2611...
261100.1.5Saudi ArabiaMaleYesYes Megaloblastic anemiaNM_001081.3:c.434G>AHomozygousAutosomal, RecessiveTanner et al. 2004 Relative of 261100.1...
261100.1.6Saudi ArabiaMaleYesYes Megaloblastic anemiaNM_001081.3:c.434G>AHomozygousAutosomal, RecessiveTanner et al. 2004 Relative of 261100.1...
261100.1.7Saudi ArabiaMaleYesYes Megaloblastic anemiaNM_001081.3:c.434G>AHomozygousAutosomal, RecessiveTanner et al. 2004 Relative of 261100.1...

Other Reports

Bahrain

For the first time from Bahrain, Al-Ajmi et al, 2003, described a rare case of pernicious anemia (PA) in a young female.

Kuwait

Ismail et al, 1997, reported seven patients in two unrelated consanguineous Bedouin families with Grasbeck-Imerslund syndrome. In Family one, three affected male sibs, had a deceased brother, who died of severe anemia, and seven apparently healthy sisters, suggesting an X-linked mode of inheritance. Family two had four affected and four healthy sibs alluding to a possible autosomal recessive mode of inheritance. 

Tanner et al, 2004, studied two unrelated Kuwaiti families with a total of 7 patients affected by megaloblastic anemia. No mutations were uncovered in the CUBN or AMN genes. 

Lebanon

Rossler et al, 2003, described four children from a Lebanese family with megaloblastic anemia. The patients had a late onset of disease and no proteinuria.  

Saudi Arabia

Abdelaal and Ahmed, 1991, reported a Saudi family affected by megaloblastic anemia. The patients included an 18 year old male proband, his 15 year old sibling and 6 year old first cousin.

Al Essa et al, 1998, described two Saudi sisters with this disorder. In children, early anemia usually leads to the diagnosis. In this case, however, the presence of hemoglobinopathy that required frequent transfusions masked the usual macrocytosis, and the older sister was not diagnosed until the age of 12 years when neurologic changes became apparent. Dementia and paralysis responded remarkably to treatment, despite the late diagnosis.

Bulut et al, 2012,  described a case of Imersland-Grasbeck Syndrome in a 17-month-old Saudi Arabian boy.  

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