GM11110

GM11110 LCL from B-Lymphocyte

Description:

PHENYLKETONURIA

Affected:

Yes

Sex:

Male

Age:

3 YR (At Sampling)

Overview

Repository

NIGMS Human Genetic Cell Repository

Subcollection

Heritable Diseases

Class

Disorders of Amino Acid Metabolism

Biopsy Source

Peripheral vein

Cell Type

B-Lymphocyte

Tissue Type

Blood

Transformant

Epstein-Barr Virus

Sample Source

LCL from B-Lymphocyte

Race

White

Family Member

Relation to Proband

brother

Confirmation

Clinical summary/Case history

Species

Homo sapiens

Common Name

Human

Remarks

Clinically affected; on dietary therapy; hyperphenylalaninemia; donor subject is a compound heterozygote: one allele has a A>G transition at nucleotide 1241 in exon 12 of the PAH gene [c.1241A>G] resulting in a pathogenic substitution of cysteine for tyrosine at codon 414 [p.Tyr414Cys (p.Y414C)] and a second allele has a pathogenic splice site mutation at nucleotide 1315, c.1315+1G>A [IVS12+1G>A].

Characterizations

IDENTIFICATION OF SPECIES OF ORIGIN

Species of Origin Confirmed by Nucleoside Phosphorylase, Glucose-6-Phosphate Dehydrogenase, and Lactate Dehydrogenase Isoenzyme Electrophoresis

Gene

PAH

Chromosomal Location

12q24.1

Allelic Variant 1

261600.0017; HYPERPHENYLALANINEMIA, NON-PKU

Identified Mutation

TYR414CYS (c. 1241A>G); This mutation in exon 12 was found on haplotype 4 in a Caucasian patient (Okano et al., 1991). An A-to-G transition at the second base of codon 414 was responsible. In vitro expression studies showed that the tyr414-to-cys mutation produced a protein with a significant amount of PAH enzyme activity, i.e., approximately 50% of normal steady-state levels.

Gene

PAH

Chromosomal Location

12q24.1

Allelic Variant 2

261600.0001; PHENYLKETONURIA

Identified Mutation

IVS12DS, G>A, +1 (c.1315+1 G>A); The first PKU mutation identified in the PAH gene was a single base change (GT-to-AT) in the canonical 5-prime splice donor site of intron 12 (DiLella et al., 1986). Direct hybridization analysis using specific oligonucleotide probes demonstrated tight association with a specific RFLP haplotype called haplotype 3. The splicing mutation was the most prevalent PKU allele among Caucasians. Marvit et al. (1987) found that the GT-to-AT substitution at the 5-prime splice donor site of intron 12 resulted in the skipping of the preceding exon during RNA splicing. cDNA clones had shown an internal 116-basepair deletion corresponding precisely to exon 12 and leading to the synthesis of the truncated protein lacking the C-terminal 52 amino acids. Gene transfer and expression studies using the mutant PAH cDNA indicated that the deletion abolished PAH activity in the cell as a result of protein instability. The studies of Marvit et al. (1987) indicated that in fact a single nucleotide substitution rather than a deletion was the basis of the abnormal gene product.