Clinical study of tetrahydrobiopterin responsive phenylalanine hydroxylase deficiency in southern and northern Chinese patients / 中华医学遗传学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To analyze characteristics of different hyperphenylalaninemia (HPA) and to discuss the clinical difference between southern and northern Chinese patients with tetrahydrobiopterin (BH4) responsive phenylalanine hydroxylase (PAH) deficiency.</p><p><b>METHODS</b>(1)BH4 (20 mg/kg) loading test was performed in all 108 HPA patients. These patients, 63 males and 45 females, were at a mean age of 7.05 months. A combined phenylalanine (Phe) and BH4 loading test was carried out in the patients who had a basic blood Phe concentration less than 600 micromol/L. The urine pterine profile analysis and the dihydropteridine reductase (DHPR) activity in dry blood filter spot were analyzed simultaneously. (2)BH4 responsive patients were divided to southern and northern groups by their parent's native place and geographic boundary determined by Changjiang River. The change of Phe concentration after BH4 loading test was compared between the two groups.</p><p><b>RESULTS</b>(1)Among the 108 HPA cases, 36 patients (33.3%) were BH4 responsive PAH deficiency, 49 (45.4%) were non-BH4 no responsive phenylketonuria (PKU)and 23(21.3%)were BH4 deficiency (BH4D). The Phe concentration of patients with BH4 responsive PAH deficiency decreased by 49.24% and 65.35% at 8 h and 24 h after oral BH4, 23 in southern group and 13 in northern group among 36 patients. (2)The mean Phe concentration at 24 h after loading test in southern and northern groups were (217.02+/-189.03) micromol/L and 458.75+/-342.54 micromol/L respectively (P<0.05), although the decrease percent of plasma Phe concentration at 2 h, 4 h, 8 h, 24 h was no distinct difference between southern and northern groups (P>0.05).</p><p><b>CONCLUSION</b>Most of mild and moderate HPA patients affected by PAH deficiency show plasma Phe concentration decrease >30% in 24 h after oral BH4 20 mg/kg, few are classic PKU. The responsiveness to BH4 is no difference between southern and northern Chinese patients with BH4 responsive PAH deficiency according to the decrease percent of plasma Phe concentration, although the Phe concentration is lower in southern patients than that in northern patients.</p>