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Home , Fetal hemoglobin, Globin

Guidelines for Ordering Testing

Suspected Condition Recommended Tests to Order Notes and Guidance

1 Beta- sequencing and deletion mapping are Sickle Disease HBB (β-globin) gene sequencing recommended to differentiate homozygous (e.g. Hb SS) 2 SS, SC, Sβ-thalassemia HBB (β-globin) locus deletion/duplication analysis (MLPA) and compound heterozygous states (e.g. Hb SC, Sβ- SE, SD, SO, S-HPFH, S-Other 3 HBA (α-globin) locus deletion/duplication analysis (MLPA) thalassemia, S-HPFH). Alpha-globin copy number can modify phenotype of . 1 HBB (β-globin) gene sequencing Thalassemia Comprehensive testing is highly recommended because α, β, (δβ), (γδβ), (εγδβ) 2 HBB (β-globin) locus deletion/duplication analysis (MLPA) of the complexity of the thalassemia syndromes, and the α triplications/quadruplications 3 HBA (α-globin) sequencing fact that the phenotype of thalassemia is modified by the Hb E disorders genotypes of both the α-globin and β-globin loci. Hb Constant Spring, others 4 HBA (α-globin) locus deletion/duplication analysis (MLPA) Both panels are recommended to differentiate Common β-variants 1 HBB (β-globin) gene sequencing homozygous (e.g. Hb CC) and compound heterozygous Hb C, D, O, others 2 HBB (β-globin) locus deletion/duplication analysis (MLPA) states (e.g. Hb Cβ-thalassemia, Hb C-HPFH). For Hb E, use the guidance for thalassemia. Both panels are recommended because sequence variants Common α-variants 1 HBA (α-globin) gene sequencing can occur on a chromosome with 1 or 2 α-globin genes, and α-globin gene copy number affects the proportion of 2 Hb G-Philadelphia, Hb I, others HBA (α-globin) locus deletion/duplication analysis (MLPA) the variant Hb. For Hb Constant Spring (and related Hbs), use the guidance for thalassemia. Other 1 HBB (β-globin) gene sequencing These Hb disorders are sequence variants of either the Unstable Hb, Altered Affinity 2 HBA (α-globin) genes sequencing α-globin or β-globin genes. Hb, (Hb M)

1 HBB (β-globin) gene sequencing Possible Hb Disorder 2 HBB (β-globin) locus deletion/duplication analysis (MLPA) Comprehensive testing is recommended. or Complex Genotype 3 HBA (α-globin) genes sequencing 4 HBA (α-globin) locus deletion/duplication analysis (MLPA)

Key: minimum recommended testing suggested testing

Laboratory of Genetics and Genomics CLIA#: 36D0656333 l Phone: (513) 636-4474 l Fax: (513) 636-4373 Email: [email protected] l www.cincinnatichildrens.org/genetics Guidelines for Ordering Genetic Testing for Disorders of (Hb F)

Suspected Condition Recommended Tests to Order Notes and Guidance

Neonatal (transient) 1 HBG (γ-globin) gene sequence analysis thalassemia syndrome 2 HBB (β-globin) locus deletion/duplication analysis (MLPA)

Hereditary persistence of Includes: HBG (γ-globin) gene sequence analysis, 1 HPFH gene analysis HBB (β-globin) locus deletion/duplication analysis (MLPA) fetal hemoglobin (HPFH) and HPFH SNP analysis

Abnormal phenotype ± Abnormal phenotypes may include hemolysis, cyanosis, 1 HBG (γ-globin) gene sequence analysis abnormal Hb analysis , polycythemia, and methemoglobinemia.

Abnormal Hb analysis only 1 HBG (γ-globin) gene sequence analysis No clinical phenotype.

Key: minimum recommended testing suggested testing

Laboratory of Genetics and Genomics CLIA#: 36D0656333 l Phone: (513) 636-4474 l Fax: (513) 636-4373 Email: [email protected] l www.cincinnatichildrens.org/genetics BRV276497 11-20