Cytopenias and congenital anaemias
Gene: HBA2

HBA2 (hemoglobin subunit alpha 2)
EnsemblGeneIds (GRCh38): ENSG00000188536
EnsemblGeneIds (GRCh37): ENSG00000188536
OMIM: 141850, Gene2Phenotype
HBA2 is in 7 panels

4 reviews

Arianna Tucci (Genomics England Curator)

Green List (high evidence)

There are two alpha globin genes (HBA1 and HBA2), which are encoded in tandem on chromosome 16. Different Mutations in HBA1/HBA2 are associated with different α-thalassemias and different mode of inheritance: 1) α-thalassemia silent carrier: deletion/mutation that leads to loss of 1 α-globin gene (either HBA1 or HBA2) 2) α-thalassemia trait: deletion/mutations that leads to the loss of 2 α-globin genes either in cis (--/αα) or in trans (-α/-α); 3) Hemoglobin H disease is caused by contiguous gene deletion of HBA1 and HBA2 genes on one chromosome, and a defect (deletional / inactivating small indel /single nucletide variant), in either HBA1 or HBA2 on the other chromosome; 4) 'homozygous alpha-thalassemia' (fatal hydrops fetalis): usually caused by deletions on both chromosomes, leading no/little production of alpha globin and death in utero. The phenotypes relevant to this panel are the α-thalassemia trait and the Hemoglobin H disease. Mostly caused by deletions but rare cases of small indels or point mutations leading to decreased production of the alpha globin chans have been described (16798638, 15481890, 15182057 for example)
Created: 11 Mar 2017, 8:56 p.m.

Comment on mode of inheritance: see comment above
Created: 10 Mar 2017, 4:30 p.m.

Mode of inheritance
BOTH monoallelic and biallelic, autosomal or pseudoautosomal

Phenotypes
Heinz body anemias, 140700; Hemoglobin H disease, nondeletional 613978, alpha thalassemia

Mode of pathogenicity
Other

Created: 10 Mar 2017, 4:23 p.m.

Panel version: 0.536

Sarah Leigh (Genomics England Curator)

Comment on mode of inheritance: Monoallelic inheritance reported for Heinz body anemia,140700, no information provided in OMIM for the other phenotypes
Created: 9 Mar 2017, 5:05 p.m.

Created: 9 Mar 2017, 5:05 p.m.

Panel version: 0.530

Louise Daugherty (Genomics England Curator)

Comment on list classification: Needs further discussion with clinical team
Created: 2 Mar 2017, 2:40 p.m.

Created: 2 Mar 2017, 2:40 p.m.

Panel version: 0.304

BRIDGE consortium (NIHRBR-RD)

Green List (high evidence)

Mode of inheritance
BOTH monoallelic and biallelic, autosomal or pseudoautosomal

Phenotypes
Globin Disorder

Variants in this GENE are reported as part of current diagnostic practice

Created: 16 Jan 2017, 3:46 p.m.

Panel version: Imported from "Anaemias and red cell disorders" panel version 0.9

Details

Mode of Inheritance

BOTH monoallelic and biallelic, autosomal or pseudoautosomal

Sources

Expert Review Green
Radboud University Medical Center, Nijmegen

Phenotypes

Erythrocytosis 7, OMIM:617981
Heinz body anemia, OMIM:140700
Hemoglobin H disease, deletional and nondeletional, OMIM:613978
Thalassemia, alpha-, OMIM:604131

Tags

cnv structural-variant

OMIM

141850

Clinvar variants

Variants in HBA2

Penetrance

Complete

Mode of Pathogenicity

Other - please provide details in the comments

Panels with this gene

History Filter Activity

3 Nov 2022, Gel status: 3

Set Phenotypes

Arina Puzriakova (Genomics England Curator)

Phenotypes for gene: HBA2 were changed from Globin Disorder; Erythrocytosis; Heinz body anemia,140700; Hemoglobin H disease, nondeletional, 613978; Hypochromic microcytic anemia; Thalassemia, alpha-, 60413 to Erythrocytosis 7, OMIM:617981; Heinz body anemia, OMIM:140700; Hemoglobin H disease, deletional and nondeletional, OMIM:613978; Thalassemia, alpha-, OMIM:604131

14 Mar 2017, Gel status: 4

Set mode of pathogenicity

Ellen McDonagh (Genomics England Curator)

Mode of pathogenicity for HBA2 was changed to Other - please provide details in the comments

11 Mar 2017, Gel status: 4