![]() Hemoglobin H disease (intermedia form) : three defective alleles (-/-α) → results in excessive production of pathologically altered HbH.Children of parents with a two- gene deletion in cis are at higher risk of developing Hb Bart.Cis-deletion is common amongst Asian populations, whereas trans-deletions are more common in African populations.Silent carrier (minima form) : one defective allele (-α/αα).The severity of alpha thalassemia depends on the number of defective α-globin alleles. Thus, there are four forms of the disease. In a normal cell, the α-globin chains are coded by a total of four alleles. Inheritance pattern: autosomal recessive.The α-globin gene cluster is located on chromosome 16.Alpha thalassemia : usually due to deletion of at least one out of the four existing alleles.β-globin locus - short arm of chromosome 11.Beta thalassemia: usually due to point mutations in promoter sequences or splicing sites.Combination of one defective β-globin allele and one defective HbS allele (β +/ HbS or β 0/ HbS).Severe hemolytic anemia (that requires frequent transfusions).Variable anemia that may require transfusions during periods of stress (e.g., surgery, infection, pregnancy).Two defective alleles (β +/β + or β +/β 0) or coinheritance of other variants.Consists of four γ-chains ( γ-tetramers ).Chronic hemolytic anemia (that may require transfusions).Minor forms of thalassemia usually require no treatment, while patients with thalassemia intermedia/major typically require regular blood transfusions and management of disease and treatment-related complications (e.g., chelating agent for transfusion-mediated iron overload). The diagnostic workup for suspected thalassemia includes a blood smear, hemoglobin electrophoresis, high-performance liquid chromatography ( HPLC), and, possibly, genetic testing. The key feature in all forms of thalassemia is microcytic hypochromic anemia (which may be very mild in minor forms), but more severe forms may also manifest with hemolysis, splenomegaly, delay in growth and development, and skeletal deformities. Thalassemia mutations are generally more frequent in areas where malaria is endemic alpha thalassemias occur most commonly in individuals of Asian or African descent, whereas beta thalassemias are predominant in individuals of Mediterranean descent. The number of alleles affected is directly related to the severity of the disease (minor/intermedia/major). Thalassemias can be further classified according to the specific genotype: the α-chain is coded by four alleles, resulting in four possible variants depending on the number of alleles affected, while the β-chain is coded by two alleles, resulting in two possible variants. Adenoid facies – developmental facial traits caused by adenoid hypertrophy, nasal airway obstruction and mouthbreathing really a form of long face syndrome.Thalassemias are a group of hereditary hemoglobin disorders characterized by mutations on the α- or β-globin chains (resulting in alpha or beta thalassemia).Coarse facies – many inborn errors of metabolism.Bovine facies (or cow face) – craniofacial dysostosis or crouzon syndrome. ![]() Ashen grey facies – myocardial infarction.Plethoric facies – Cushing's syndrome and polycythemia vera.Amiodarone facies (deep blue discoloration around malar area and nose).Leonine facies – lepromatous leprosy or craniometaphyseal dysplasia.Moon face (also known as "Cushingoid facies") – Cushing's syndrome.Hippocratic facies – eyes are sunken, temples collapsed, nose is pinched with crusts on the lips, and the forehead is clammy.As a fifth declension noun, facies can be both singular and plural. In medical contexts, a facies is a distinctive facial expression or appearance associated with a specific medical condition. Facial abnormalities associated with Crouzon syndrome
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