Paraoxonase 1 status in keratoconus: a preliminary study of activity and polymorphism / Estatus de la paraoxonasa 1 en el queratocono: estudio preliminar de actividad y polimorfismo

OBJECTIVE: To determine the activity of paraoxonase 1 (PON1) in keratoconus in a Malaysian population in comparison with non-keratoconic subjects. METHODS: Clinical eye examinations were performed on patients with keratoconus and non-keratoconic subjects after questionnaires were completed. Blood samples were collected and subjected to spectrophotometry analysis of paraoxonase and diazoxonase activities for the determination of the status of PON1 of every individual. RESULTS: Of the 11 keratoconic patients and 55 non-keratoconic control samples collected, eight patients of Indian ethnicity were keratoconic (73%), whereas 33 non-Indians were non-keratoconic (60%; p = 0.047). Paraoxonase activity was lower in Indians compared to the non-Indians ie Malays and Chinese (p = 0.008). Keratoconic subjects had a lower paraoxonase activity compared to non-keratoconics (p = 0.038). CONCLUSIONS: The reduced paraoxonase activity in keratoconic patients suggests that the keratoconic corneas were more susceptible to oxidative stress. Reduced paraoxonase activity and keratoconus status appears to be associated with ethnicity.

OBJETIVO: Determinar la actividad de paraoxonasa 1 (Pon 1) en el queratocono en una población malaya, en comparación con sujetos no queratocónicos. MÉTODOS: Se realizaron exámenes clínicos oculares a pacientes con queratocono y a sujetos no queratocónicos luego que los mismos respondieran a los cuestionarios. Se recogieron muestras de sangre, que fueron entonces sometidas a análisis espectrofotométrico en relación con las actividades de la paraoxonasa y la diazoxonasa para la determinación del estatus de la paraoxonasa 1 de cada individuo. RESULTADOS: De los 11 pacientes queratocónicos y las 55 muestras de control no queratocónicas recogidas, 8 pacientes de etnicidad india fueron queratocónicos (73%), mientras que 33 no indios fueron no queratocónicos (60%; p = 0.047). La actividad de la paraoxonasa fue más baja en los indios en comparación con los no indios, es decir, los malayos y los chinos (p = 0.008). Los sujetos queratocónicos tenían una actividad de la paraoxonasa más baja, comparada con los no queratocónicos (p = 0.038). CONCLUSIONES: La actividad de la paraoxonasa reducida en los pacientes queratocónicos sugiere que las córneas queratocónicas son más susceptibles al estrés oxidativo. La actividad de la paraoxonasa reducida y el estatus del queratocono parecen estar asociados con la etnicidad.

Concurrent Inheritance of Deletional α-thalassaemia in Malays with HbE Trait

Introduction: HbE is the commonest beta haemoglovin (Hb) variant in Southeast Asia. It causes a reduction in synthesis of beta-globin E (βE) chain. Studies indicate HbE coinherited with α-thalassaemia leads to a milder clinical phenotype. This study investigates the concomitant inheritance of α-thalassaemia in Malays with HbE. Methods: Four hundred and fourteen (414) blood samples were screened for haemoglobinopathy using primarily the first 3 steps of the BHES [(B) blood counts, blood film: (H), HPLC; (E),elstrophoresis; (S),stability)] protocol. Complete blood counts were generated on an automated blood cell analyser, HB typing with cation exchange high-performance liquid chromatography (HPLC) and Hb typing with cation exchange high-performance liquid chromatography (HPLC) and Hb electrophoresis at an alkaline pH (pH 8.5). Forty-five (10.9%) were identified as HbE trait and DNA analysis was done for deletional α-thalassaemia using a single-tube multiplex-PCR assay. Results: Among the 45 subjects with HbE trait. 4 (8.9%) were found to have alpha-thalassaemia-2 (α⁺) (α-3.7 kb deletion) and 1 (2.2%) the alpha-thalassaemia-1 (α⁰) (—SEA 20.5kb deletion) defects respectively. Discussion: These findings show that 11.1% of Malays with HbE inherit alpha-thalassaemia concurrently. The most prevalent interaction found was a double heterozygote for HbE/α-thalassaemia 2, followed by HbE/α-thalassaemia 1. Conclusion: Molecular screening of deletional α-thalassaemia identified its concurrent inheritance in 11.1% of Malays who were HbE carriers. This information will guide genetic counseling and the planning of treatment modalities in patients with HbE alpha-thalassaemia.