Introduction:
Maple syrup urine disease (MSUD) is an autosomal recessive amino acid disorder, affecting approximately 1 in 220 000 live births [1]. MSUD is caused by aberrancy of the branched-chain alpha-ketoacid dehydrogenase complex enzyme, thus disabling branched chain amino acid (BRAA) metabolism. Toxic accumulation of BRAA, especially leucine, may cause a metabolic crisis, including weight loss, lethargy, seizures and death, especially in early infancy. The risk of a metabolic crisis persists throughout the affected individual’s life and can be exacerbated by physiological stress. We present a case of a grand-multiparous woman and her partner who are carriers for MSUD.
Case presentation:
A 33-year-old woman and her consanguineous partner are carriers for MSUD. Her second and third child died at 20 days of life due to MSUD whilst living in Lybia. In Australia, her 4th pregnancy was terminated due to MSUD-affected foetus. Her 5th child was diagnosed with MSUD at birth as she did not have genetic testing in early pregnancy. The infant required intensive care at birth but is alive and well. Our care for her 6th pregnancy included chorionic villus sampling at 13 weeks demonstrating a heterozygous genotype. Post-partum, the infant underwent paediatric review at delivery and at 6 weeks and remains well.
Discussion:
Due to advances in management of inherited metabolic conditions, more women affected by or carriers of previously fatal diseases are able to thrive and build families of their own.
Women with MSUD present a challenge to pregnancy care providers as the physiological state of pregnancy can have a significant impact on the affected woman and the gestate. Pregnancy is an anabolic state, thus women require careful titration of protein intake and monitoring of their plasma leucine levels by multidisciplinary teams. Delivery should be planned prudently, as the catabolic stress of labour can trigger a crisis, as can surgical intervention, especially if they are to remain nil by mouth. Furthermore, protein turnover during breastfeeding require caloric and protein optimization for these women.
Pre-conception counselling for all women and/or partners who have MSUD or are carriers for the gene is ideal. Pre-implantation or early pregnancy genetic testing should be offered with counselling targeted at patient’s values and needs.
Conclusion:
MSUD is a rare metabolic, inherited disease. Women who are affected or carriers require close surveillance and multi-disciplinary input. Prenatal and early pregnancy counselling should be individualized and targeted by the patient’s needs and available resources.