Prenatal diagnosis of phenylketonuria and bilateral renal agenesis in a fetus

Abstract

Phenylketonuria (PKU) is a congenital, genetically determined metabolic disorder of the essential amino acid phenylalanine (PA). PKU is caused by mutation in the phenylalanine hydroxylase gene (PAH). In different populations PKU affects about one in 8,000–15,000 newborns. PKU, as an orphan disease, per se, rarely occurs in conjunction with any other congenital and hereditary pathology. This is precisely why the concurrent combination of the rare pathology of various genesis in one patient presents an undoubted clinical interest. The paper reports on the case of early prenatal diagnosis of PKU and bilateral renal agenesis (BRA) in one fetus of the first trimester of pregnancy. BRA has an estimated incidence of one in 3,000–5,000 births. The paper also discusses the specific features of ultrasonic prenatal diagnosis of BRA in the І-ІІ trimesters of pregnancy. The med literature data shows that 9% of first-degree relatives of a fetus with BRA have various congenital anomalies of kidneys, the majority of which are asymptomatic. In this case, ultrasound scanning of all family members ruled out any morphological abnormalities of their kidneys. Based on the average frequency of BRA (1: 5,000) and PKU (1: 7,000) indicated in various med literature sources, the probability of such event makes 1: 35 000 000 cases, which illustrates the rarity of this findings. Authors of article analyzed the PKU’s encounter with various hereditary and congenital pathologies registered in “Multiregional Center of Medical Genetics and Prenatal Diagnosis named after P.M. Veropotvelyan” between 1986 and 2017. According to research, the encounter rate of PKU with other hereditary and congenital pathology makes 1:31 among patients with PKU and 1: 278 215 among all newborns surveyed for this period in the southeastern and central Ukraine.

Keywords

• phenylketonuria
• renal agenesis
• potter anomalad (sequencing)
• ultrasound prenatal diagnosis
• invasive prenatal diagnosis
• chorionic villus biopsy
• molecular genetic studies