NonPatientCell: E-Coli (DH5α)

GeneFunction: GO:0006559

GeneAlteration: PAH cDNA was cloned into a pMAL-c2E expression vector encoding an N-terminal MBP tag and an enterokinase cleavage site. PAH mutants were constructed using site-directed mutagenesis and confirmed using DNA sequencing. Both the wild-type and the 10 mutant vectors were transformed into E. coli DH5α via overexpresion of fusion proteins at midexponential phase. The proteins were purified and concentration was determined.

FunctionalEvidence: Expression of the 10 mutant proteins compared to the wild-type demonstrated that several of these mutants induce protein destabilization and subsequent loss of function. Upon deconvolution analysis, five variants showed significanly distrubed oligomerization and a preponderance to misfold and form high-molecular-weight protein aggregates. Enzyme kinetic parameter analysis demonstrated moderate reduction in PAH activity and severely affected allostery in all but one mutation, indicating the strong possibility of global confirmational changes. Protein confirmation was tested by limited proteolysis with proteinase K with six out of eight tested mutants decreasing the half-life of the protein by >50% and decreased stability in five out of eight. Thermal protein denaturation was analyzed by fluorescence and demonstrated that all of the mutations led to substantial distortion of the protein's confirmation and/or loss of structural integrity compared to the wild-type, especially those in the regulatory domain. Finally, amino acid replacements were shown to disrupt local networks of amino acid interactions and alter the normal oligomeric state and therfore the function of the protein.

FAVariant1: NM_000277.3(PAH):c.1222C>T (p.Arg408Trp)

ClinVar: 577 https://www.ncbi.nlm.nih.gov/clinvar/variation/577/

FAVariant2: NM_000277.3(PAH):c.898G>T (p.Ala300Ser)

ClinVar: 92751 https://www.ncbi.nlm.nih.gov/clinvar/variation/92751/

FAVariant3: NM_000277.3(PAH):c.165T>G (p.Phe55Leu)

ClinVar: 92734 https://www.ncbi.nlm.nih.gov/clinvar/variation/92734/

FAVariant4: NM_000277.3(PAH):c.1249T>C (p.Tyr417His)

ClinVar: 102579 https://www.ncbi.nlm.nih.gov/clinvar/variation/102579/

FAVariant5: NM_000277.3(PAH):c.940C>T (p.Pro314Ser)

ClinVar: 102905 https://www.ncbi.nlm.nih.gov/clinvar/variation/102905/

CaseF7P: 1 yr report, India

CasePresentingHPOs: HP:0001010, HP:0000750, HP:0001249, HP:0006801, HP:0004923 (Hypopigmentation of the skin, Delayed speech and language development, Intellectual disability, Brisk deep tendon reflexes, Hyperphenylalaninemia)

HPOsFreeText: N/A

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Family is consanguinous, Father was confirmed heterozygous, Proband is heterozygous for this mutation with no second pathogenic mutation located

CasePreviousTesting: Blood phenylalanine before treatment was 1105 μmol/l, Blood tyrosine before treatment was 87 μmol/l, PKU diagnosis was based on ferric chloride test on patient urine samples and detection of elevated Phenylalanine levels in blood samples by using HPLC, in addition to analysis of clinical features.

CaseGenotypingMethod: Genomic DNA was isolated from blood samples of proband and family members. PCR amplification and sequencing was used to screen for mutations. Each mutation was confirmed by bi-directional DNA sequencing.

Variant: NM_000277.3:c.*144A>G

CAID: CA16020999 http://reg.clinicalgenome.org/redmine/projects/registry/genboree_registry/by_caid?caid=CA16020999

gnomAD: 0.001284, http://gnomad.broadinstitute.org/variant/12-103232809-T-C

CaseF3P: 4 yrs report, India

CasePresentingHPOs: HP:0001010, HP:0000750, HP:0001249, HP:0006801, HP:0004923 (Hypopigmentation of the skin, Delayed speech and language development, Intellectual disability, Brisk deep tendon reflexes, Hyperphenylalaninemia)

HPOsFreeText: N/A

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Family is consanguinous, Parents were confirmed heterozygous, Variant may not undergo NMD however would be missing essential domains (but PAH level supports some residual function)

CasePreviousTesting: Blood phenylalanine before treatment was 439 μmol/l, Blood tyrosine before treatment was 121 μmol/l, PKU diagnosis was based on ferric chloride test on patient urine samples and detection of elevated Phenylalanine levels in blood samples by using HPLC, in addition to analysis of clinical features.

CaseGenotypingMethod: Genomic DNA was isolated from blood samples of proband and family members. PCR amplification and sequencing was used to screen for mutations. Each mutation was confirmed by bi-directional DNA sequencing.

Variant: NM_000277.3:c.976del (p.Trp326Glyfs*15)

CAID: CA16020912 http://reg.clinicalgenome.org/redmine/projects/registry/genboree_registry/by_caid?caid=CA16020912

gnomAD: Not in gnomAD

CaseF4P: 4 yrs report, India

CasePresentingHPOs: HP:0001010, HP:0000750, HP:0001249, HP:0006801, HP:0004923 (Hypopigmentation of the skin, Delayed speech and language development, Intellectual disability, Brisk deep tendon reflexes, Hyperphenylalaninemia)

HPOsFreeText: N/A

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Family is consanguinous, Parents were confirmed heterozygous, Variant disrupts the WT donor site and is predicted to alter splicing

CasePreviousTesting: Blood phenylalanine before treatment was 1150 μmol/l, Blood tyrosine before treatment was 30 μmol/l, PKU diagnosis was based on ferric chloride test on patient urine samples and detection of elevated Phenylalanine levels in blood samples by using HPLC, in addition to analysis of clinical features.

CaseGenotypingMethod: Genomic DNA was isolated from blood samples of proband and family members. PCR amplification and sequencing was used to screen for mutations. Each mutation was confirmed by bi-directional DNA sequencing.

Variant: NM_000277.3(PAH):c.60+5G>A

ClinVar: 120281 https://www.ncbi.nlm.nih.gov/clinvar/variation/120281/

gnomAD: Not in gnomAD

CaseF5S: 21 yrs report, India

CasePresentingHPOs: N/A

HPOsFreeText: N/A

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Variant has been shown to abolish canonical splice donor site and lead to a null protein

CasePreviousTesting: Blood phenylalanine before treatment was 1698 μmol/l, Blood tyrosine before treatment was 37 μmol/l

CaseGenotypingMethod: N/A

Variant: NM_000277.3(PAH):c.842+1G>A

ClinVar: 599 https://www.ncbi.nlm.nih.gov/clinvar/variation/599/

gnomAD: 0.00007752, http://gnomad.broadinstitute.org/variant/12-103246592-C-T

CaseF5P: 18 yrs report, India

CasePresentingHPOs: N/A

HPOsFreeText: N/A

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Proband for Family 5, Variant has been shown to abolish canonical splice donor site and lead to a null protein

CasePreviousTesting: Blood phenylalanine before treatment was 1260 μmol/l, Blood tyrosine before treatment was 36 μmol/l

CaseGenotypingMethod: N/A

Variant: NM_000277.3(PAH):c.842+1G>A

ClinVar: 599 https://www.ncbi.nlm.nih.gov/clinvar/variation/599/

gnomAD: 0.00007752, http://gnomad.broadinstitute.org/variant/12-103246592-C-T

CaseF1S: 5 yrs report, India

CasePresentingHPOs: N/A

HPOsFreeText: N/A

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Variant is demonstrated to activate a cryptic splice site and abolish the canon splice site leading to a premature termination and nonsense-mediated decay

CasePreviousTesting: Blood phenylalanine before treatment was 1431 μmol/l, Blood tyrosine before treatment was 35 μmol/l

CaseGenotypingMethod: N/A

Variant: NM_000277.3(PAH):c.169-2A>G

ClinVar: 555212 https://www.ncbi.nlm.nih.gov/clinvar/variation/555212/

gnomAD: 0.00003267, http://gnomad.broadinstitute.org/variant/12-103288698-T-C

CaseF2P: 2 yrs report, India

CasePresentingHPOs: HP:0001010, HP:0000750, HP:0001249, HP:0006801, HP:0004923 (Hypopigmentation of the skin, Delayed speech and language development, Intellectual disability, Brisk deep tendon reflexes, Hyperphenylalaninemia)

HPOsFreeText: N/A

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Family is consanguinous, Parents were confirmed heterozygous, Variant may not undergo NMD however would be missing essential domains and is predicted to be null

CasePreviousTesting: Blood phenylalanine before treatment was 1619 μmol/l, Blood tyrosine before treatment was 60 μmol/l, PKU diagnosis was based on ferric chloride test on patient urine samples and detection of elevated Phenylalanine levels in blood samples by using HPLC, in addition to analysis of clinical features.

CaseGenotypingMethod: Genomic DNA was isolated from blood samples of proband and family members. PCR amplification and sequencing was used to screen for mutations. Each mutation was confirmed by bi-directional DNA sequencing.

Variant: NM_000277.3:c.1177_1178insT (p.Asn393Ilefs*2)

CAID: CA16020958 http://reg.clinicalgenome.org/redmine/projects/registry/genboree_registry/by_caid?caid=CA16020958

gnomAD: Not in gnomAD

CaseF1P: Female, 8 yrs report, India

CasePresentingHPOs: N/A

HPOsFreeText: N/A

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Proband for Family 1, Variant is demonstrated to activate a cryptic splice site and abolish the canon splice site leading to a premature termination and nonsense-mediated decay

CasePreviousTesting: Blood phenylalanine before treatment was 1174 μmol/l, Blood tyrosine before treatment was 33 μmol/l

CaseGenotypingMethod: N/A

Variant: NM_000277.3(PAH):c.169-2A>G

ClinVar: 555212 https://www.ncbi.nlm.nih.gov/clinvar/variation/555212/

gnomAD: 0.00003267, http://gnomad.broadinstitute.org/variant/12-103288698-T-C

CaseF6P: 1 yr report, India

CasePresentingHPOs: HP:0001010, HP:0000750, HP:0001249, HP:0006801, HP:0004923 (Hypopigmentation of the skin, Delayed speech and language development, Intellectual disability, Brisk deep tendon reflexes, Hyperphenylalaninemia)

HPOsFreeText: N/A

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Family is consanguinous, Predicted to undergo NMD

CasePreviousTesting: Blood phenylalanine before treatment was 1260 μmol/l, Blood tyrosine before treatment was N/A μmol/l, PKU diagnosis was based on ferric chloride test on patient urine samples and detection of elevated Phenylalanine levels in blood samples by using HPLC, in addition to analysis of clinical features.

CaseGenotypingMethod: Genomic DNA was isolated from blood samples of proband and family members. PCR amplification and sequencing was used to screen for mutations. Each mutation was confirmed by bi-directional DNA sequencing.

Variant: NM_000277.3(PAH):c.526C>T (p.Arg176Ter)

ClinVar: 102723 https://www.ncbi.nlm.nih.gov/clinvar/variation/102723/

gnomAD: 0.00008012, http://gnomad.broadinstitute.org/variant/12-103249094-G-A

CaseBII-1: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 890 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Proband for Family B

Variant1: NM_000277.3(PAH):c.1222C>T (p.Arg408Trp)

ClinVar: 577 https://www.ncbi.nlm.nih.gov/clinvar/variation/577/

gnomAD: 0.001766, https://gnomad.broadinstitute.org/variant/12-102840493-G-A?dataset=gnomad_r3

Variant2: NM_000277.3(PAH):c.1241A>G (p.Tyr414Cys)

ClinVar: 593 https://www.ncbi.nlm.nih.gov/clinvar/variation/593/

gnomAD: 0.0005264, https://gnomad.broadinstitute.org/variant/12-102840474-T-C?dataset=gnomad_r3

CaseEII-2: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 320 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: N/A

Variant1: NM_000277.3(PAH):c.1222C>T (p.Arg408Trp)

ClinVar: 577 https://www.ncbi.nlm.nih.gov/clinvar/variation/577/

gnomAD: 0.001766, https://gnomad.broadinstitute.org/variant/12-102840493-G-A?dataset=gnomad_r3

Variant2: NM_000277.3(PAH):c.533A>G (p.Glu178Gly)

ClinVar: 92746 https://www.ncbi.nlm.nih.gov/clinvar/variation/92746/

gnomAD: 0.0001473, https://gnomad.broadinstitute.org/variant/12-103249087-T-C

CaseCI-1: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 365 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: N/A

Variant1: NM_000277.3(PAH):c.194T>C (p.Ile65Thr)

ClinVar: 636 https://www.ncbi.nlm.nih.gov/clinvar/variation/636/

gnomAD: 0.0005574, https://gnomad.broadinstitute.org/variant/12-102894893-A-G?dataset=gnomad_r3

Variant2: NM_000277.3(PAH):c.261C>A (p.Ser87Arg)

ClinVar: 583 https://www.ncbi.nlm.nih.gov/clinvar/variation/583/

gnomAD: 0.00009294, https://gnomad.broadinstitute.org/variant/12-102894826-G-T?dataset=gnomad_r3

CaseDII-3: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 725 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: N/A

Variant1: NM_000277.3(PAH):c.561G>A (p.Trp187Ter)

ClinVar: 102736 https://www.ncbi.nlm.nih.gov/clinvar/variation/102736/

gnomAD: 0.00001760, https://gnomad.broadinstitute.org/variant/12-103249059-C-T

Variant2: NM_000277.3(PAH):c.782G>C (p.Arg261Pro)

ClinVar: 102832 https://www.ncbi.nlm.nih.gov/clinvar/variation/102832/

gnomAD: Not in gnomAD

CaseDII-2: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 970 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: N/A

Variant1: NM_000277.3(PAH):c.561G>A (p.Trp187Ter)

ClinVar: 102736 https://www.ncbi.nlm.nih.gov/clinvar/variation/102736/

gnomAD: 0.00001760, https://gnomad.broadinstitute.org/variant/12-103249059-C-T

Variant2: NM_000277.3(PAH):c.782G>C (p.Arg261Pro)

ClinVar: 102832 https://www.ncbi.nlm.nih.gov/clinvar/variation/102832/

gnomAD: Not in gnomAD

CaseAII-4: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 2085 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Proband for Family A

Variant1: NM_000277.3(PAH):c.165del (p.Phe55fs)

ClinVar: 611 https://www.ncbi.nlm.nih.gov/clinvar/variation/611/

gnomAD: 0.00002639, https://gnomad.broadinstitute.org/variant/12-103306571-CA-C?dataset=gnomad_r3

Variant2: NM_000277.3(PAH):c.143T>C (p.Leu48Ser)

ClinVar: 608 https://www.ncbi.nlm.nih.gov/clinvar/variation/608/

gnomAD: 0.001025, https://gnomad.broadinstitute.org/variant/12-102912816-A-G?dataset=gnomad_r3

CaseBI-1: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 375 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: N/A

Variant1: NM_000277.3(PAH):c.1222C>T (p.Arg408Trp)

ClinVar: 577 https://www.ncbi.nlm.nih.gov/clinvar/variation/577/

gnomAD: 0.001766, https://gnomad.broadinstitute.org/variant/12-102840493-G-A?dataset=gnomad_r3

Variant2: NM_000277.3(PAH):c.688G>A (p.Val230Ile)

ClinVar: 102784 https://www.ncbi.nlm.nih.gov/clinvar/variation/102784/

gnomAD: 0.0009025, https://gnomad.broadinstitute.org/variant/12-102855154-C-T?dataset=gnomad_r3

CaseEI-1: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 430 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: N/A

Variant1: NM_000277.3(PAH):c.1066-11G>A

ClinVar: 607 https://www.ncbi.nlm.nih.gov/clinvar/variation/607/

gnomAD: 0.0004116, https://gnomad.broadinstitute.org/variant/12-103237568-C-T

Variant2: NM_000277.3(PAH):c.533A>G (p.Glu178Gly)

ClinVar: 92746 https://www.ncbi.nlm.nih.gov/clinvar/variation/92746/

gnomAD: 0.0001473, https://gnomad.broadinstitute.org/variant/12-103249087-T-C

CaseAI-1: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 330 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: N/A

Variant1: NM_000277.3(PAH):c.143T>C (p.Leu48Ser)

ClinVar: 608 https://www.ncbi.nlm.nih.gov/clinvar/variation/608/

gnomAD: 0.001025, https://gnomad.broadinstitute.org/variant/12-102912816-A-G?dataset=gnomad_r3

Variant2: NM_000277.3(PAH):c.898G>T (p.Ala300Ser)

ClinVar: 92751 https://www.ncbi.nlm.nih.gov/clinvar/variation/92751/

gnomAD: 0.006318, https://gnomad.broadinstitute.org/variant/12-102851701-C-A?dataset=gnomad_r3

CaseDI-1: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 365 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: N/A

Variant1: NM_000277.3(PAH):c.561G>A (p.Trp187Ter)

ClinVar: 102736 https://www.ncbi.nlm.nih.gov/clinvar/variation/102736/

gnomAD: 0.00001760, https://gnomad.broadinstitute.org/variant/12-103249059-C-T

Variant2: NM_000277.3(PAH):c.898G>T (p.Ala300Ser)

ClinVar: 92751 https://www.ncbi.nlm.nih.gov/clinvar/variation/92751/

gnomAD: 0.006318, https://gnomad.broadinstitute.org/variant/12-102851701-C-A?dataset=gnomad_r3

CaseAII-5: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 440 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: N/A

Variant1: NM_000277.3(PAH):c.165del (p.Phe55fs)

ClinVar: 611 https://www.ncbi.nlm.nih.gov/clinvar/variation/611/

gnomAD: 0.00002639, https://gnomad.broadinstitute.org/variant/12-103306571-CA-C?dataset=gnomad_r3

Variant2: NM_000277.3(PAH):c.898G>T (p.Ala300Ser)

ClinVar: 92751 https://www.ncbi.nlm.nih.gov/clinvar/variation/92751/

gnomAD: 0.006318, https://gnomad.broadinstitute.org/variant/12-102851701-C-A?dataset=gnomad_r3

CaseAII-3: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 370 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: N/A

Variant1: NM_000277.3(PAH):c.165del (p.Phe55fs)

ClinVar: 611 https://www.ncbi.nlm.nih.gov/clinvar/variation/611/

gnomAD: 0.00002639, https://gnomad.broadinstitute.org/variant/12-103306571-CA-C?dataset=gnomad_r3

Variant2: NM_000277.3(PAH):c.898G>T (p.Ala300Ser)

ClinVar: 92751 https://www.ncbi.nlm.nih.gov/clinvar/variation/92751/

gnomAD: 0.006318, https://gnomad.broadinstitute.org/variant/12-102851701-C-A?dataset=gnomad_r3

CaseCII-1: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 1515 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: N/A

Variant1: NM_000277.3(PAH):c.194T>C (p.Ile65Thr)

ClinVar: 636 https://www.ncbi.nlm.nih.gov/clinvar/variation/636/

gnomAD: 0.0005574, https://gnomad.broadinstitute.org/variant/12-102894893-A-G?dataset=gnomad_r3

Variant2: NM_000277.3(PAH):c.1065+1G>A

ClinVar: 102501 https://www.ncbi.nlm.nih.gov/clinvar/variation/102501/

gnomAD: 0.00004622, http://gnomad.broadinstitute.org/variant/12-103238113-C-T

CaseAII-2: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 375 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: N/A

Variant1: NM_000277.3(PAH):c.165del (p.Phe55fs)

ClinVar: 611 https://www.ncbi.nlm.nih.gov/clinvar/variation/611/

gnomAD: 0.00002639, https://gnomad.broadinstitute.org/variant/12-103306571-CA-C?dataset=gnomad_r3

Variant2: NM_000277.3(PAH):c.898G>T (p.Ala300Ser)

ClinVar: 92751 https://www.ncbi.nlm.nih.gov/clinvar/variation/92751/

gnomAD: 0.006318, https://gnomad.broadinstitute.org/variant/12-102851701-C-A?dataset=gnomad_r3

CaseBII-2: N/A

CasePresentingHPOs: N/A

HPOsFreeText: Pretreatment phenylalanine level at 270 umol/L

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: N/A

Variant1: NM_000277.3(PAH):c.688G>A (p.Val230Ile)

ClinVar: 102784 https://www.ncbi.nlm.nih.gov/clinvar/variation/102784/

gnomAD: 0.0009025, https://gnomad.broadinstitute.org/variant/12-102855154-C-T?dataset=gnomad_r3

Variant2: NM_000277.3(PAH):c.1241A>G (p.Tyr414Cys)

ClinVar: 593 https://www.ncbi.nlm.nih.gov/clinvar/variation/593/

gnomAD: 0.0005264, https://gnomad.broadinstitute.org/variant/12-102840474-T-C?dataset=gnomad_r3

CaseC: Male, Childhood onset, Asian, China

CasePresentingHPOs: HP:0004923 (Hyperphenylalaninemia)

HPOsFreeText: N/A

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Parents are confirmed heterozyogus and proband is homozygous for this mutation

CasePreviousTesting: "Classical Severe PKU" presence confirmed by Guthrie test and clinical criteria described in PMID:7006308, Plasma phenylalanine level in excess of 20 mg/dl, Homozygous for RFLP haplotype 4

CaseGenotypingMethod: PCR amplification of PAH exon three plus the flanking intronic regions was performed. The genomic DNA was cloned and sequenced to confirm the presence of the mutation. Haplotype analysis confirmed linkage disequillibrium with RFLP haplotype 4.

Variant: NM_000277.3(PAH):c.331C>T (p.Arg111Ter)

ClinVar: 581 https://www.ncbi.nlm.nih.gov/clinvar/variation/581/

gnomAD: 0.0001230, https://gnomad.broadinstitute.org/variant/12-103288534-G-A

NonHumanModel: Mouse (Mus musculus)

GeneAlteration: Mutations were induced in mice germline cells at a rate near 10^-3 per locus via an alkylating agent called ethylnitrosourea. Inbred BTBR males were treated with this agent and bred to normal BTBR females. Three hundred and fifty progeny were screened for mutations that did not complement the previous model PAH_enu1 and if present bred to a previous homozygote and tested for hyperphenylalaninemia. A PHE clearance test was performed in questionable cases. For those that tested positive the carrier parents were mated to a normal BTBR partner to establish a cogenic mutant line. Western blot confirmed reduced to absent CRM in liver.

ModelPhenotype: HP:0007513, HP:0000707, HP:0005982, HP:0100610, HP:0004923, HP:0001510, HP:0000252 (Generalized hypopigmentation, Abnormality of the nervous system, Reduced phenylalanine hydroxylase activity, Maternal hyperphenylalaninemia, Hyperphenylalaninemia, Growth delay, Microcephaly)

ModelFreeText: Serum PHE concentrations were 15x wild-type for PAH_enu2 (23.1 +/- 6.9 mg/dl, 1.5 +/- 0.5 reference) and 14x wild-type for PAH_enu3 (20.3 +/- 5.9 mg/dl, 1.5 +/- 0.5 reference), PAH activity was reduced to <1% wild-type for PAH_enu2 (0 +/- 2 delta O.D. x 10^3/min/mg protein, 40 +/- 6 reference) and <10% wild-type for PAH_enu3 (5 +/- 5 delta O.D. x 10^3/min/mg protein, 40 +/- 6 reference)

HumanPhenotype: HP:0007513, HP:0000707, HP:0005982, HP:0100610, HP:0004923, HP:0000252 (Generalized hypopigmentation, Abnormality of the nervous system, Reduced phenylalanine hydroxylase activity, Maternal hyperphenylalaninemia, Hyperphenylalaninemia, Microcephaly)

HumanFreeText: N/A

ModelEvidence: PAH_enu2 has been further characterized many times and results from a missense variant in PAH (PMID: 9119379). PAH_enu3 has also been further characterized and results from a canonical splicing variant in PAH (PMID:11161825). Both models fully recapitulate the phenotypes we expect to see in phenylketonuria, including the quintessential elevated PHE levels and significantly decreased PAH activity. Also of note is the progressive hypopigmentation, microcephaly, growth delay, and neurological abnormalities which are all seen in human probands without proper intervention. Maternal hyperphenylalaninemia is also recapitulated, with no pups surviving beyond several hours with standard breeding diet when born to a mother with the homozygous genotype. Diets low in PKU resulted in less severe symptoms, similar to low protein diets in human probands.

ModelVariant1: NM_000277.3(PAH):c.788T>C (p.Phe263Ser)

ClinVar: 619150 https://www.ncbi.nlm.nih.gov/clinvar/variation/619150/

ModelVariant2: NM_000277.3(PAH):c.1199+2T>G

ClinVar: 557365 https://www.ncbi.nlm.nih.gov/clinvar/variation/557365/

CaseF2: Female, 6 yrs report, Italy

CasePresentingHPOs: HP:0004923 (Hyperphenylalaninemia)

HPOsFreeText: N/A

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Parents do not appear to be tested, DNA sequence analysis "shows the sense sequence expected of compound heterozygotes with two comigrating bands seen"

CasePreviousTesting: Pre-treatment phenylalanine levels determined soon after birth were above 20 mg / 100 ml, Proband has been under treatment since birth and currently tolerates less than 20 mg Phe/kg bodyweight per day

CaseGenotypingMethod: DNA as isolated from leukocytes and haplotype analysis performed. Enzymatic digestion of PCR-amplified DNA fragments was performed and DGGE analysis of all 13 exons and flanking introns were carried out. The resulting samples containing abberant bands were sequenced and cleaved by MaeI and MaeIII for analysis.

Variant1: NM_000277.3(PAH):c.620A>G (p.Asn207Ser)

ClinVar: 102765 https://www.ncbi.nlm.nih.gov/clinvar/variation/102765/

gnomAD: Not in gnomAD

Variant2: NM_000277.3(PAH):c.842C>T (p.Pro281Leu)

ClinVar: 589 https://www.ncbi.nlm.nih.gov/clinvar/variation/589/

gnomAD: 0.0002016, https://gnomad.broadinstitute.org/variant/12-103246593-G-A

CaseF1: Male, 6 yrs report, Italy

CasePresentingHPOs: HP:0004923 (Hyperphenylalaninemia)

HPOsFreeText: N/A

CaseNotHPOs: N/A

NotHPOsFreeText: N/A

CaseAddInfo: Parents were confirmed heterozygous, Splicing variant is predicted to lead to a null protein

CasePreviousTesting: Pre-treatment phenylalanine levels determined soon after birth were above 20 mg / 100 ml, Proband has been under treatment since birth and currently tolerates less than 20 mg Phe/kg bodyweight per day

CaseGenotypingMethod: DNA as isolated from leukocytes and haplotype analysis performed. Enzymatic digestion of PCR-amplified DNA fragments was performed and DGGE analysis of all 13 exons and flanking introns were carried out. The resulting samples containing abberant bands were sequenced and cleaved by MaeI and MaeIII for analysis.

Variant1: NM_000277.2(PAH):c.611A>G (p.Tyr204Cys)

ClinVar: 590 https://www.ncbi.nlm.nih.gov/clinvar/variation/590

gnomAD: 0.0001632, https://gnomad.broadinstitute.org/variant/12-103249009-T-C

Variant2: NM_000277.2(PAH):c.442-2A>C

ClinVar: 120276 https://www.ncbi.nlm.nih.gov/clinvar/variation/120276

gnomAD: Not in gnomAD

RescueModel: Mouse (Mus musculus)

GeneAlteration: PAH_enu2 mice were purchased and bred to obtain the homozygotic mice for this study. Original Generation Method: Mutations were induced in mice germline cells at a rate near 10^-3 per locus via an alkylating agent called ethylnitrosourea. Inbred BTBR males were treated with this agent and bred to normal BTBR females. Three hundred and fifty progeny were screened for mutations that did not complement the previous model PAH_enu1 and if present bred to a previous homozygote and tested for hyperphenylalaninemia. A PHE clearance test was performed in questionable cases. For those that tested positive the carrier parents were mated to a normal BTBR partner to establish a cogenic mutant line. Western blot confirmed reduced to absent CRM in liver.

RescuePhenotype: HP:0007513, HP:0004923, HP:0005982, HP:0100610 (Generalized hypopigmentation, Hyperphenylalaninemia, Reduced phenylalanine hydroxylase activity, Maternal hyperphenylalaninemia)

RescueMethod: The human PAH expression vector plasmid pAAV2-EF-hPAH-WPRE was created by subcloning a full-length human PAH cDNA into a preexisitng parent vector by substitution with eGFP cDNA. Alos included is an EF promoter, woodchuck hepatitis virus post-transcriptional element, and bovine growth hormone poly (A) signal. The rep2/cap2 plasmid or rep2/cap8 plasmid was used to package the vector and produce the final rAAV2/2-hPAH and rAAV2/8-hPAH vectors by triple plasmid transfection. Five-to-six week old PAH_enu2 mice were anesthetized with ketamine-xylazine and infused with viral particles of rAAV2/2-hPAH or rAAV2/8-hPAH through the hepatic portal vein or tail vein.

RescueEvidence: PAH activity in the livers of treated mice six weeks after treatment recovered to 58.43±5.73% and 89.25±8.79% of the wild-type activity in female and male PAH_enu2 mice respectively compared to <1% WT in untreated mice. Plasma phenylalanine concentration in female PAH_enu2 mice infused with rAAV2/8-hPAH vectors decreased markedly to 110±34.5 µM at two weeks from 2,891±336.2 µM and showed continued significant phenylalanine clearance for six month after rAAV2/8-hPAH infusion. Male PAH_enu2 showed a similar reduction, though they started at a lower base concentration of 1,800.6±233.7 µM. The fur color of treated mice also changed from greyish to black from one week after delivery with sustained fur color changes over the entire six month period. Investiation of effects on pregnant mice revealed a complete recovery of fetus length and body weight compared to the untreated mice (1.746±0.203 cm and 774±144 mg for untreated VS 2.081±0.269 cm and 916±67 mg for treated). Spontaneous abortion rate also normalized to 4.55±5.89% from 30.95±14.27%. The rAAV-hPAH genome was not found in the placentae or fetuses nor did the genome of fetuses affect the development parameters.

ModelVariant: NM_000277.3(PAH):c.788T>C (p.Phe263Ser)

ClinVar: 619150 https://www.ncbi.nlm.nih.gov/clinvar/variation/619150/

ExperimentName: PAH Variant Rescued by FokI-Cas9

RescueCellLine: Cytotoxic T cell (CL:0000910) AKA COS-7 Cell Line

GeneAlteration: A wild-type PAH cDNA was introduced into a vector via XbaI and BamHI cleavage after amplification from the plasmid. The mutation was introduced via site-directed mutagenesis and confirmed via Sanger sequencing. COS-7 cells were seeded and cultured before being transfected with either the mutant vector or the wild-type control. The resulting clone was characterized through RT-PCR and expanded.

RescueCellPhenotype: HP:0005982 (Reduced phenylalanine hydroxylase activity)

RescueMethod: The FokI-dCas9-IRES-ZsGreen1 plasmid was created by designing gRNAs to target the 1222C>T variant and synthesizing a final sgRNA expression fragment which was cloned into the base vector. Electroporation was then performed on the COS-7 cells with the expression vectors incorporated. Flow cytometry analysis confirmed that 18.4% of cells co-expressed both the FokI-dCas9 and the sgRNA.The cells were treated with the ssODN that represents the replacement sequence and confirmed via Sanger sequencing. Any off-target sites were anlyzed via Sanger sequencing and displayed no evidence of off-target cleavage.

RescueEvidence: Western blot analysis performed on cell expressing the wild-type PAH and those treated with differing levels of ODN and RS-1 showed that those treated with the replacement sequence had significantly higher PAH expression than the mutant cells that were not transfected with the vectors. Further, liquid chromatography-electrospray ionization tandem mass spectrometry was used to evaluate PAH activity after repair showing an activity of 22.08 +/- 1.67 % with the RS-1 expressed as opposed to 16.86+/- 1.31 % without the replacement sequence.

RescueCellVariant: NM_000277.3(PAH):c.1222C>T (p.Arg408Trp)

ClinVarID: 577 https://www.ncbi.nlm.nih.gov/clinvar/variation/577/