TY - JOUR
T1 - Identification and characterization of hydroxymethylbilane synthase mutations causing acute intermittent porphyria
T2 - Evidence for an ancestral founder of the common G111R mutation
AU - De Siervi, A.
AU - Rossetti, M. V.
AU - Parera, V. E.
AU - Astrin, K. H.
AU - Aizencang, G. I.
AU - Glass, I. A.
AU - Batlle, A. M.Del C.
AU - Desnick, R. J.
PY - 1999
Y1 - 1999
N2 - Acute intermittent porphyria (AIP), the most common hepatic porphyria, results from the half-normal activity of hydroxymethylbilane synthase (HMB- synthase; EC 4.3.1.8), the third enzyme in the heme biosynthetic pathway. Because life-threatening acute neurologic attacks of this autosomal dominant disease are triggered by various ecogenic factors (e.g., certain drugs, hormones, alcohol, and starvation), efforts have been directed to identify and counsel presymptomatic heterozygotes in affected families to avoid the precipitating factors. Thus, to determine the nature of the mutations causing AIP in 26 unrelated enzyme-confirmed patients from Argentina, a long-range polymerase chain reaction method was developed to amplify the entire 10-kb gene in two fragments for efficient cycle sequencing and mutation detection. Eight new mutations were identified including two missense mutations (Q34P and G335S), four small deletions (728delCT, 815delAGGA, 948delA, and 985del12), a single base insertion (666insA), and a splice site mutation (IVS12+1). In addition, five previously reported mutations (G111R, R173W, Q204X, R201W, and 913insC) were detected. Notably, G111R was identified in 12 of the 26 (46%) presumably unrelated propositi; however, haplotype analysis with intragenic and flanking markers indicated an ancestral founder. Expression of the two new missense mutations (Q34P and G335S) in E. coli resulted in 2.5% or less of the normal expressed enzyme, confirming their defective function. Thus, eight new and five previously reported HMB-synthase mutations, including a common lesion, were detected, permitting accurate identification and counseling of presymptomatic carriers in these 26 unrelated Argentinean AIP families with this dominant porphyria.
AB - Acute intermittent porphyria (AIP), the most common hepatic porphyria, results from the half-normal activity of hydroxymethylbilane synthase (HMB- synthase; EC 4.3.1.8), the third enzyme in the heme biosynthetic pathway. Because life-threatening acute neurologic attacks of this autosomal dominant disease are triggered by various ecogenic factors (e.g., certain drugs, hormones, alcohol, and starvation), efforts have been directed to identify and counsel presymptomatic heterozygotes in affected families to avoid the precipitating factors. Thus, to determine the nature of the mutations causing AIP in 26 unrelated enzyme-confirmed patients from Argentina, a long-range polymerase chain reaction method was developed to amplify the entire 10-kb gene in two fragments for efficient cycle sequencing and mutation detection. Eight new mutations were identified including two missense mutations (Q34P and G335S), four small deletions (728delCT, 815delAGGA, 948delA, and 985del12), a single base insertion (666insA), and a splice site mutation (IVS12+1). In addition, five previously reported mutations (G111R, R173W, Q204X, R201W, and 913insC) were detected. Notably, G111R was identified in 12 of the 26 (46%) presumably unrelated propositi; however, haplotype analysis with intragenic and flanking markers indicated an ancestral founder. Expression of the two new missense mutations (Q34P and G335S) in E. coli resulted in 2.5% or less of the normal expressed enzyme, confirming their defective function. Thus, eight new and five previously reported HMB-synthase mutations, including a common lesion, were detected, permitting accurate identification and counseling of presymptomatic carriers in these 26 unrelated Argentinean AIP families with this dominant porphyria.
KW - Acute intermittent porphyria
KW - Argentinian AIP patients
KW - HMB- synthase deficiency
KW - Hydroxymethylbilane synthase
KW - Mutation analysis
KW - Porphyria
UR - http://www.scopus.com/inward/record.url?scp=0032881791&partnerID=8YFLogxK
U2 - 10.1002/(sici)1096-8628(19991008)86:4<366::aid-ajmg11>3.0.co;2-%23
DO - 10.1002/(sici)1096-8628(19991008)86:4<366::aid-ajmg11>3.0.co;2-%23
M3 - Article
C2 - 10494093
AN - SCOPUS:0032881791
SN - 0148-7299
VL - 86
SP - 366
EP - 375
JO - American Journal of Medical Genetics
JF - American Journal of Medical Genetics
IS - 4
ER -