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The mode of inheritance of ovalocytosis/elliptocytosis in Malaysian Orang Asli families

Fix AG, Baer AS, Lie-Injo LE

Hum Genet, 1982;61(3):250-3.
PMID: 7173868 DOI: 10.1007/bf00296452

Hereditary ovalocytosis/elliptocytosis occurs in polymorphic frequencies among several Malaysian populations and also in Melanesia. Although the condition has been described as an autosomal dominant, Melanesian family studies suggest that it is inherited recessively. Based on 75 Orang Asli families, it is shown that the Malaysian form of elliptocytosis is most likely inherited as an autosomal dominant. It appears, therefore, that either the inference of recessive inheritance in Melanesians is incorrect or that the ovalocytosis/elliptocytosis phenotypes are due to distinct genetic entities in the two regions.

Matched MeSH terms: Elliptocytosis, Hereditary/genetics*
Co-inheritance of Southeast Asian Ovalocytosis (SAO) and G6PD deficiency associated with acute hemolysis in a Thai patient

Prayongratana K, Viprakasit V

Blood Cells Mol. Dis., 2019 11;79:102347.
PMID: 31323480 DOI: 10.1016/j.bcmd.2019.102347
Matched MeSH terms: Elliptocytosis, Hereditary/genetics*
Elliptocytosis, malaria, and fertility in Malaysia

Baer A

Hum Biol, 1988 Dec;60(6):909-15.
PMID: 3235080
Matched MeSH terms: Elliptocytosis, Hereditary/genetics*
Fulltext Distal renal tubular acidosis and hereditary elliptocytosis in a single family

Thong MK, Tan AA, Lin HP

Singapore Med J, 1997 Sep;38(9):388-90.
PMID: 9407765

Distal renal tubular acidosis (RTA) and hereditary elliptocytosis (HE) are apparently distinct, genetic conditions. We report a family with 3 children having both hereditary elliptocytosis and distal renal tubular acidosis. The simultaneous occurrence of these two conditions in three siblings could be due to covariations in the same family, although a possible contiguous gene syndrome for distal RTA and HE cannot be excluded. This report emphasises the importance of excluding a renal tubular defect in any child who presents with elliptocytosis and failure to thrive.

Matched MeSH terms: Elliptocytosis, Hereditary/genetics
The evolutionary origins of Southeast Asian Ovalocytosis

Paquette AM, Harahap A, Laosombat V, Patnode JM, Satyagraha A, Sudoyo H, et al.

Infect Genet Evol, 2015 Aug;34:153-9.
PMID: 26047685 DOI: 10.1016/j.meegid.2015.06.002

Southeast Asian Ovalocytosis (SAO) is a common red blood cell disorder that is maintained as a balanced polymorphism in human populations. In individuals heterozygous for the SAO-causing mutation there are minimal detrimental effects and well-documented protection from severe malaria caused by Plasmodium vivax and Plasmodium falciparum; however, the SAO-causing mutation is fully lethal in utero when homozygous. The present-day high frequency of SAO in Island Southeast Asia indicates the trait is maintained by strong heterozygote advantage. Our study elucidates the evolutionary origin of SAO by characterizing DNA sequence variation in a 9.5 kilobase region surrounding the causal mutation in the SLC4A1 gene. We find substantial haplotype diversity among SAO chromosomes and estimate the age of the trait to be approximately 10,005 years (95% CI: 4930-23,200 years). This date is far older than any other human malaria-resistance trait examined previously in Southeast Asia, and considerably pre-dates the widespread adoption of agriculture associated with the spread of speakers of Austronesian languages some 4000 years ago. Using a genealogy-based method we find no evidence of historical positive selection acting on SAO (s=0.0, 95% CI: 0.0-0.03), in sharp contrast to the strong present-day selection coefficient (e.g., 0.09) estimated from the frequency of this recessively lethal trait. This discrepancy may be due to a recent increase in malaria-driven selection pressure following the spread of agriculture, with SAO targeted as a standing variant by positive selection in malarial populations.

Matched MeSH terms: Elliptocytosis, Hereditary/genetics*
Fulltext Homozygous haemoglobin E in association with hereditary ovalocytosis

George E, Kudva MV

Med J Malaysia, 1989 Sep;44(3):255-8.
PMID: 2626141

Hereditary stomatocytic ovalocytosis and haemoglobin E are two genes present in 3-5% of Malays. This is a report of a 22 year old Malay college student with homozygous haemoglobin E and hereditary stomatocytic ovalocytosis where the clinical effects seen were the result of the summation of these genes: he was asymptomatic, presenting with moderate jaundice, moderate hepatosplenomegaly, and a mild haemolytic anaemia.

Matched MeSH terms: Elliptocytosis, Hereditary/genetics*
Southeast Asian Ovalocytosis and Hemoglobinopathies in Newborns: Prevalence, Molecular, and Hematologic Analyses

Yamsri S, Kawon W, Duereh A, Fucharoen G, Fucharoen S

J Pediatr Hematol Oncol, 2021 04 01;43(3):e341-e345.
PMID: 32815885 DOI: 10.1097/MPH.0000000000001920

OBJECTIVES: Southeast Asian ovalocytosis (SAO) is an inherited red blood cell (RBC) membrane disorder, whereas hemoglobinopathies are inherited globin gene disorders. In an area where both diseases are prevalent, the interaction between them resulting in variable hematologic parameters can be encountered. However, little is known about the genetic interaction of SAO and thalassemia. We investigated the prevalence of SAO and hemoglobinopathy genotypes among newborns in southern Thailand.
PATIENTS AND METHODS: This study was carried out on 297 newborns recruited consecutively at Naradhiwas Rajanagarindra Hospital in the south of Thailand. The SAO was identified on blood smear examination and polymerase chain reaction analysis. Thalassemia genotypes were defined. Hematologic parameters and hemoglobin (Hb) profiles were recorded and analyzed.
RESULTS: Among 297 newborns, 15 (5.1%) carried SAO, whereas 70 (23.6%) had thalassemia with 15 different thalassemia genotypes. Abnormal Hb including Hb C, Hb Q-Thailand, and Hb D-Punjab were observed in 5 newborns. It was found in the nonthalassemic newborns that RBC count, Hb, and hematocrit of the nonthalassemic newborns with SAO were significantly lower than those without SAO. The same finding was also observed in the thalassemic newborns; RBC count, Hb, and hematocrit of the thalassemic newborns with SAO were significantly lower than those without SAO. However, the mean corpuscular volume, mean corpuscular Hb, and RBC distribution width of the SAO-newborns were significantly higher.
CONCLUSIONS: Both SAO and hemoglobinopathy genotypes are common in southern Thailand. One should take this into consideration when evaluating neonatal anemia and other hematologic abnormalities. Identification of both genetic defects and long-term monitoring on the clinical outcome of this genetic interaction should be essential to understand the pathogenesis of these common genetic disorders in the region.

Matched MeSH terms: Elliptocytosis, Hereditary/genetics
Band 3 mutations, renal tubular acidosis and South-East Asian ovalocytosis in Malaysia and Papua New Guinea: loss of up to 95% band 3 transport in red cells

Bruce LJ, Wrong O, Toye AM, Young MT, Ogle G, Ismail Z, et al.

Biochem. J., 2000 Aug 15;350 Pt 1:41-51.
PMID: 10926824

We describe three mutations of the red-cell anion exchangerband 3 (AE1, SLC4A1) gene associated with distalrenal tubular acidosis (dRTA) in families from Malaysia and Papua NewGuinea: Gly(701)-->Asp (G701D), Ala(858)-->Asp(A858D) and deletion of Val(850) (DeltaV850). The mutationsA858D and DeltaV850 are novel; all three mutations seem to berestricted to South-East Asian populations. South-East Asianovalocytosis (SAO), resulting from the band 3 deletion of residues400-408, occurred in many of the families but did not itselfresult in dRTA. Compound heterozygotes of each of the dRTA mutationswith SAO all had dRTA, evidence of haemolytic anaemia and abnormal red-cell properties. The A858D mutation showed dominant inheritance and therecessive DeltaV850 and G701D mutations showed a pseudo-dominantphenotype when the transport-inactive SAO allele was also present. Red-cell and Xenopus oocyte expression studies showed that theDeltaV850 and A858D mutant proteins have greatly decreased aniontransport when present as compound heterozygotes (DeltaV850/A858D,DeltaV850/SAO or A858D/SAO). Red cells with A858D/SAO had only 3% ofthe SO(4)(2-) efflux of normal cells, thelowest anion transport activity so far reported for human red cells. The results suggest dRTA might arise by a different mechanism for eachmutation. We confirm that the G701D mutant protein has an absoluterequirement for glycophorin A for movement to the cell surface. Wesuggest that the dominant A858D mutant protein is possibly mis-targetedto an inappropriate plasma membrane domain in the renal tubular cell,and that the recessive DeltaV850 mutation might give dRTA because ofits decreased anion transport activity.

Matched MeSH terms: Elliptocytosis, Hereditary/genetics*
High prevalence of Southeast Asian ovalocytosis in Malays with distal renal tubular acidosis

Yusoff NM, Van Rostenberghe H, Shirakawa T, Nishiyama K, Amin N, Darus Z, et al.

J Hum Genet, 2003;48(12):650-653.
PMID: 14618420 DOI: 10.1007/s10038-003-0095-2

Southeast Asian ovalocytosis (SAO) is a red blood cell abnormality common in malaria-endemic regions and caused by a 27 nt deletion of the band 3 protein gene. Since band 3 protein, also known as anion exchanger 1, is expressed in renal distal tubules, the incidence of SAO was examined in distal renal tubular acidosis (dRTA) in Malays in Kelantan, Malaysia. Twenty-two patients with dRTA and 50 healthy volunteers were examined for complication of SAO by both morphological and genetic analyses. SAO was identified in 18 of the 22 dRTA patients (81.8%), but only two of the 50 controls (4%). The incidence of SAO was significantly high in those with dRTA (p<0.001), indicating a dysfunctional role for band 3 protein/anion exchanger 1 in the development of dRTA.

Matched MeSH terms: Elliptocytosis, Hereditary/genetics*
Deletion in erythrocyte band 3 gene in malaria-resistant Southeast Asian ovalocytosis

Jarolim P, Palek J, Amato D, Hassan K, Sapak P, Nurse GT, et al.

Proc Natl Acad Sci U S A, 1991 Dec 15;88(24):11022-6.
PMID: 1722314

Southeast Asian ovalocytosis (SAO) is a hereditary condition that is widespread in parts of Southeast Asia. The ovalocytic erythrocytes are rigid and resistant to invasion by various malarial parasites. We have previously found that the underlying defect in SAO involves band 3 protein, the major transmembrane protein, which has abnormal structure and function. We now report two linked mutations in the erythrocyte band 3 gene in SAO: (i) a deletion of codons 400-408 and (ii) a substitution, A----G, in the first base of codon 56 leading to substitution of Lys-56 by Glu-56. The first defect leads to a deletion of nine amino acids in the boundary of cytoplasmic and membrane domains of band 3. This defect has been detected in all 30 ovalocytic subjects from Malaysia, the Philippines, and two unrelated coastal regions of Papua New Guinea, whereas it was absent in all 30 controls from Southeast Asia and 20 subjects of different ethnic origin from the United States. The Lys-56----Glu substitution has likewise been found in all SAO subjects. However, it has also been detected in 5 of the 50 control subjects, suggesting that it represents a linked polymorphism. We conclude that the deletion of codons 400-408 in the band 3 gene constitutes the underlying molecular defect in SAO.

Matched MeSH terms: Elliptocytosis, Hereditary/genetics*
Genome-Wide Association for HbA1c in Malay Identified Deletion on SLC4A1 that Influences HbA1c Independent of Glycemia

Chai JF, Kao SL, Wang C, Lim VJ, Khor IW, Dou J, et al.

J Clin Endocrinol Metab, 2020 Dec 01;105(12).
PMID: 32936915 DOI: 10.1210/clinem/dgaa658

CONTEXT: Glycated hemoglobin A1c (HbA1c) level is used to screen and diagnose diabetes. Genetic determinants of HbA1c can vary across populations and many of the genetic variants influencing HbA1c level were specific to populations.
OBJECTIVE: To discover genetic variants associated with HbA1c level in nondiabetic Malay individuals.
DESIGN AND PARTICIPANTS: We conducted a genome-wide association study (GWAS) analysis for HbA1c using 2 Malay studies, the Singapore Malay Eye Study (SiMES, N = 1721 on GWAS array) and the Living Biobank study (N = 983 on GWAS array and whole-exome sequenced). We built a Malay-specific reference panel to impute ethnic-specific variants and validate the associations with HbA1c at ethnic-specific variants.
RESULTS: Meta-analysis of the 1000 Genomes imputed array data identified 4 loci at genome-wide significance (P

Matched MeSH terms: Elliptocytosis, Hereditary/genetics