Case#: Yzer_2006_Patient_441, female, age 3 months at diagnosis, Belgian maternal and Moroccan paternal origin
CasePresentingHPOs: HP:0003593 (Infantile onset), HP:0000662 (Nyctalopia), HP:0000639 (Nystagmus), HP:0007663 (Reduced visual acuity), HP:0001483 (Eye poking), HP:0000550 (Undetectable electroretinogram)
CaseHPOFreeText: The individual is described as having Leber congenital amaurosis. Age was 15 months at time of last evaluation.
CaseNotHPOs: HP:0000613 (Photophobia), HP:0000563 (Keratoconus), HP:0001098 (Abnormal fundus morphology)
CaseNotHPOFreeText: N/A
CasePreviousTesting: An LCA-specific microarray ChIP was used for initial genotyping, using antisense oligos to screen for 301 known disease-associated variants 6 LCA genes (AIPL1, CRB1, CRX, GUCY2D, RPE65, and RPGRIP1) and two early-onset RP genes (LRAT and MERTK).
CaseMethod1: Sanger sequencing of PCR products from the relevant exon of GUCY2D (or from each of the 20 exons of GUCY2D in the compound heterozygous individual with a novel variant).
CaseMethod2: N/A
CaseGenotypingMethod: The individual was initially screened using an LCA-specific microarray ChIP with antisense oligos to detect 301 known disease-associated variants 6 LCA genes (AIPL1, CRB1, CRX, GUCY2D, RPE65, and RPGRIP1) and two early-onset RP genes (LRAT and MERTK). Subsequent genotyping was performed by Sanger sequencing of PCR products from the relevant exons of the GUCY2D locus.
Variant: The individual is compound heterozygous for the NM_000180.4(GUCY2D):c.1694T>C (p.Phe565Ser) and
NM_000180.4(GUCY2D):c.2302C>T (p.Arg768Trp) variants.
ClinVar: 9350, 98563
gnomAD: The NM_000180.4(GUCY2D):c.1694T>C (p.Phe565Ser) variant exhibits a maximum allele frequency of 0.000008790 in gnomAD version 2.1.1 (in the European non-Finnish population, with no homozygotes).
https://gnomad.broadinstitute.org/variant/17-7912849-T-C?dataset=gnomad_r2_1
The NM_000180.4(GUCY2D):c.2302C>T (p.Arg768Trp) variant exhibits a maximum allele frequency of 0.0002943 in gnomAD version 2.1.1 (in the European non-Finnish population, with no homozygotes).
https://gnomad.broadinstitute.org/variant/17-7917236-C-T
VariantEvidence: PMID: 9888789 provides evidence supporting the pathogenicity of the NM_000180.4(GUCY2D):c.1694T>C (p.Phe565Ser) variant by showing that the orthologous bovine F514S point mutation severely decreases the intrinsic cyclase activity of the protein and inactivates one of its calcium-responsive activating switches, CRM1. Multiple publications have found functional defects in the NM_000180.4(GUCY2D):c.2302C>T (p.Arg768Trp) variant. PMID: 25477517 shows defective binding to its interacting partner RD3, while PMID: 20050595 and PMID: 23035049 show reduced basal enzymatic activity and inability to interact with the activity-stimulating binding partner GCAP1.
CaseAddInfo: Parents were not reported to be consanguineous. Segregation / phasing of two variants was confirmed by parental genotyping.
CasePMIDs: N/A