Genetic analysis carried out on blood-spots of phenylalanine hydroxylase-deficient newborns detected by northeastern Italian neonatal screening.
The aim of this work was to perform genetic analysis on 18 different blood-spot samples collected from neonates detected as hyperphenylalaninemic by Northeastern Italian screening program. DNA was extracted from blood-spots. Exons/introns of PAH gene were amplified by polymerase chain reaction (PCR), and PCR products were purified and sequenced with both forward and reverse primers. The most frequent mutations were IVS12nt1g>a (16.7%) and R408W, P281L and L48S (all together 11.1%). As expected, compound heterozygosity was the usual finding; homozygosity was found only in two patients with R158Q and IVS2nt5g>c mutations. The V230I mutation was reported for the first time in Italy. We found six previously described polymorphisms (V245V, IVS4nt47c>t, IVS2nt19t>c, IVS3nt-22c>t, IVS5nt-54a>g, and E280>Q280). To our knowledge, four genotypes were not previously described: R158Q/V230I present in one patient with classical PKU; and L48S/R408Q, A403V/IVS2nt-13t>g, and G272X/V230I present in patients showing HPA phenotype. Most of the mutations were located in the exons 12 and 7 and in exon/intron 2 (83.3% detection of total mutations in PKU or HPA patients of Northeastern Italy). From a practical viewpoint, the genetic analysis of blood-spots collected on Guthrie cards for neonatal screening for PKU could be a simple method to establish the genotype of neonates. Consequently, the genotype/phenotype correlation could lead to a more accurate diagnosis and prognosis for families.
Zaffanello
M
M
Department of Paediatrics, University of Verona, 37134 Verona, Italy. marco.zaffanello@univr.it
Zamboni
G
G
Maselli
M
M
Gandini
A
A
Camilot
M
M
Maffeis
C
C
Burlina
A B
AB
Tatò
L
L
D019943:Amino Acid Substitution; D004247:DNA / Q000097:blood*; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D007558:Italy; D009154:Mutation; D015997:Neonatal Screening; D010651:Phenylalanine Hydroxylase / Q000172:deficiency / Q000235:genetics*; D010661:Phenylketonurias / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic
D004247:DNA; D010651:Phenylalanine Hydroxylase