Vitamin D Deficiency With Selected Vitamin D Receptor Gene Polymorphism in Gestational Hypertension

Hypertensive disorders of pregnancy account for approximately 14% of maternal mortality globally and is the fourth leading cause of maternal mortality in Malaysia. Despite this, the mechanisms and pathogenesis are still unknown. Vitamin D deficiency (hypovitaminosis vitamin D) has been shown to be one of the causes of gestational hypertension(GH).

Several populations have observed the association of single nucleotide polymorphisms (SNPs) of vitamin D receptor (VDR) to vitamin D deficiency among pregnancy complications, including GH. Alarming cases of hypovitaminosis D in sunny areas including Malaysia, highly imply the need to understand the genetic factor. Hence, genotyping VDR variants among pregnant women is essential for early vitamin D supplementation strategy. To investigators knowledge, there has been no published study conducted among Malaysian population on the association of VDR genetic variation and GH. Therefore, this study aim to investigate the prevalence of vitamin D deficiency and its association of VDR SNPs to the development of GH among Malaysian pregnant mothers, with the main focus on Malays, representing the largest ethnic in Malaysia.

The prevalence will be determined through a cross-sectional study involving 363 pregnant women recruited in Hospital Pengajar UPM (HPUPM) and Hospital Serdang, Selangor. Relevant socio-demographic, clinical and anthropometric data will be collected using structured interviewer-administered questionnaire. Blood specimens for the analysis of vitamin D will be done. The association will be determined in a case-control study involving 180 pregnant women who fulfilled the criteria, recruited from phase 1 study. Their blood will be further analysed for the variants of the VDR gene [(BsmI(rs1544410), FokI(rs2228570), TaqI(rs731236)] to look for the association.

This study expected to provide more evidence for early personalised intervention of vitamin D supplementation due to anticipated individual genetic variability. This antenatal care programme will reduce the government expenditures, reduce maternal and fetal morbidity and mortality while strengthening Malaysia's healthcare system.

Inclusion criteria

• Malay pregnant women with gestational age between 20 weeks till 42 weeks. (The gestational age will be determined from the first day of the last menstrual cycle or measurement of fetal crown rump length)
• Malay pregnant women with viable pregnancy with or without pregnancy induced hypertension or its complications (pre-eclampsia, eclampsia, HELLP syndrome etc).
• Literate in either English or Malay languages.
• Agreement to follow-up till delivery and provision of written informed consent.

Exclusion criteria

• Non-viable pregnancy at the time of recruitment.
• Women already on vitamin D supplements or any other drugs that can interfere with vitamin D absorption or metabolism at the time of recruitment.
• Women with chronic hypertension diagnosed prior to pregnancy.
• Pregnant women with any other chronic disease that is known to affect vitamin D such as, autoimmune disease and any malignancy