Exome sequencing identifies novel genes underlying primary congenital glaucoma in the National Birth Defects Prevention Study.

BACKGROUND: Primary congenital glaucoma (PCG) affects approximately 1 in 10,000 live born infants in the United States (U.S.). PCG has a autosomal recessive inheritance pattern, and variable expressivity and reduced penetrance have been reported. Likely causal variants in the most commonly mutated gene, CYP1B1, are less prevalent in the U.S., suggesting that alternative genes may contribute to the condition. This study utilized exome sequencing to investigate the genetic architecture of PCG in the U.S. and to identify novel genes and variants. METHODS: We studied 37 family trios where infants had PCG and were part of the National Birth Defects Prevention Study (births 1997-2011), a U.S. multicenter study of birth defects. Samples underwent exome sequencing and sequence reads were aligned to the human reference sample (NCBI build 37/hg19). Variant filtration was conducted under de novo and Mendelian inheritance models using GEMINI. RESULTS: Among candidate variants, CYP1B1 was most represented (five trios, 13.5%). Twelve probands (32%) had potentially pathogenic variants in other genes not previously linked to PCG but important in eye development and/or to underlie Mendelian conditions with potential phenotypic overlap (e.g., CRYBB2, RXRA, GLI2). CONCLUSION: Variation in the genes identified in this population-based study may help to further explain the genetics of PCG.

Genetic counseling access and service delivery in New York State is variable for parents of infants with complex CFTR genotypes conferring uncertain phenotypes.

BACKGROUND: New York State (NYS) utilizes a three-tiered cystic fibrosis newborn screening (CFNBS) algorithm that includes cystic fibrosis transmembrane conductance regulator (CFTR) gene sequencing. Infants with >1 CFTR variant of potential clinical relevance, including variants of uncertain significance or varying clinical consequence are referred for diagnostic evaluation at NYS cystic fibrosis (CF) Specialty Care Centers (SCCs). AIMS: As part of ongoing quality improvement efforts, demographic, screening, diagnostic, and clinical data were evaluated for 289 CFNBS-positive infants identified in NYS between December 2017 and November 2020 who did not meet diagnostic criteria for CF and were classified as either: CFTR-related metabolic syndrome/CF screen positive, inconclusive diagnosis (CRMS/CFSPID) or CF carriers. RESULTS: Overall, 194/289 (67.1%) had CFTR phasing to confirm whether the infant's CFTR variants were in cis or in trans. Eighteen complex alleles were identified in cis; known haplotypes (p.R117H+5T, p.F508del+p.L467F, and p.R74W+p.D1270N) were the most common identified. Thirty-two infants (16.5%) with all variants in cis were reclassified as CF carriers rather than CRMS/CFSPID. Among 263 infants evaluated at an NYS SCC, 70.3% were reported as having received genetic counseling about their results by any provider, with 96/263 (36.5%) counseled by a certified genetic counselor. CONCLUSION: Given the particularly complex genetic interpretation of results generated by CFNBS algorithms including sequencing analysis, additional efforts are needed to ensure families of infants with a positive CFNBS result have CFTR phasing when needed to distinguish carriers from infants with CRMS/CFSPID, and access to genetic counseling to address implications of CFNBS results.