Contrasting painless and painful phenotypes of pediatric restless legs syndrome : a twin family study

Objective: This study was designed to investigate painless and painful subsets of pediatric restless legs syndrome (RLS) for genetic influence and for associations with iron deficiency and common pediatric pain disorders. Methods: In a twin family study, twins (3–18 years) and their oldest siblings, mothers and fathers completed questionnaires, assessing lifetime prevalence of RLS using current criteria, as well as history of iron deficiency and pediatric pain disorders. Subsets were categorized as RLS-Painless or RLS-Painful. Within twin pair analyses were conducted to assess familial and potential genetic effects for the defined subsets. Penalized maximum likelihood logistic regression was used to test familial associations. Random-effects logistic regression modeling was used in the total pediatric sample to investigate univariate and multivariate associations with the subsets. Results: Data were available for 2033 twin individuals (1007 monozygous (MZ), 1026 dizygous (DZ); 51.7% female), 688 siblings, 1013 mothers and 921 fathers. Odds ratios, correlations and casewise concordance were significantly higher in MZ than in DZ twins only for RLS-Painful. RLS-Painless, though familial (co-twin and mother), was not genetically influenced, but was independently associated with female sex (OR 0.52, p = 0.003), iron deficiency (OR 4.20, p < 0.001) and with persistent pain disorders (OR 2.28, p = 0.02). RLS-Painful was familial and was probably genetically influenced; was independently associated with non-migraine headaches (OR 2.70, p = 0.02) and recurrent abdominal pain (OR 2.07, p = 0.04). Conclusions: Pediatric RLS was heterogeneous and was categorized into contrasting painless and painful phenotypes. RLS-Painless was associated with iron deficiency while RLS-Painful accounted for the heritability of RLS

JARID2 haploinsufficiency is associated with a clinically distinct neurodevelopmental syndrome

Purpose: JARID2, located on chromosome 6p22.3, is a regulator of histone methyltransferase complexes that is expressed in human neurons. So far, 13 individuals sharing clinical features including intellectual disability (ID) were reported with de novo heterozygous deletions in 6p22–p24 encompassing the full length JARID2 gene (OMIM 601594). However, all published individuals to date have a deletion of at least one other adjoining gene, making it difficult to determine if JARID2 is the critical gene responsible for the shared features. We aim to confirm JARID2 as a human disease gene and further elucidate the associated clinical phenotype. Methods: Chromosome microarray analysis, exome sequencing, and an online matching platform (GeneMatcher) were used to identify individuals with single-nucleotide variants or deletions involving JARID2. Results: We report 16 individuals in 15 families with a deletion or single-nucleotide variant in JARID2. Several of these variants are likely to result in haploinsufficiency due to nonsense-mediated messenger RNA (mRNA) decay. All individuals have developmental delay and/or ID and share some overlapping clinical characteristics such as facial features with those who have larger deletions involving JARID2. Conclusion: We report that JARID2 haploinsufficiency leads to a clinically distinct neurodevelopmental syndrome, thus establishing gene–disease validity for the purpose of diagnostic reporting

JARID2 haploinsufficiency is associated with a clinically distinct neurodevelopmental syndrome

Purpose: JARID2, located on chromosome 6p22.3, is a regulator of histone methyltransferase complexes that is expressed in human neurons. So far, 13 individuals sharing clinical features including intellectual disability (ID) were reported with de novo heterozygous deletions in 6p22–p24 encompassing the full length JARID2 gene (OMIM 601594). However, all published individuals to date have a deletion of at least one other adjoining gene, making it difficult to determine if JARID2 is the critical gene responsible for the shared features. We aim to confirm JARID2 as a human disease gene and further elucidate the associated clinical phenotype. Methods: Chromosome microarray analysis, exome sequencing, and an online matching platform (GeneMatcher) were used to identify individuals with single-nucleotide variants or deletions involving JARID2. Results: We report 16 individuals in 15 families with a deletion or single-nucleotide variant in JARID2. Several of these variants are likely to result in haploinsufficiency due to nonsense-mediated messenger RNA (mRNA) decay. All individuals have developmental delay and/or ID and share some overlapping clinical characteristics such as facial features with those who have larger deletions involving JARID2. Conclusion: We report that JARID2 haploinsufficiency leads to a clinically distinct neurodevelopmental syndrome, thus establishing gene–disease validity for the purpose of diagnostic reporting

Standardized practices for RNA diagnostics using clinically accessible specimens reclassifies 75% of putative splicing variants

Purpose: Genetic variants causing aberrant premessenger RNA splicing are increasingly being recognized as causal variants in genetic disorders. In this study, we devise standardized practices for polymerase chain reaction (PCR)-based RNA diagnostics using clinically accessible specimens (blood, fibroblasts, urothelia, biopsy). Methods: A total of 74 families with diverse monogenic conditions (31% prenatal-congenital onset, 47% early childhood, and 22% teenage-adult onset) were triaged into PCR-based RNA testing, with comparative RNA sequencing for 19 cases. Results: Informative RNA assay data were obtained for 96% of cases, enabling variant reclassification for 75% variants that can be used for genetic counseling (71%), to inform clinical care (32%) and prenatal counseling (41%). Variant-associated mis-splicing was highly reproducible for 28 cases with samples from ≥2 affected individuals or heterozygotes and 10 cases with ≥2 biospecimens. PCR amplicons encompassing another segregated heterozygous variant was vital for clinical interpretation of 22 of 79 variants to phase RNA splicing events and discern complete from partial mis-splicing. Conclusion: RNA diagnostics enabled provision of a genetic diagnosis for 64% of recruited cases. PCR-based RNA diagnostics has capacity to analyze 81.3% of clinically significant genes, with long amplicons providing an advantage over RNA sequencing to phase RNA splicing events. The Australasian Consortium for RNA Diagnostics (SpliceACORD) provide clinically-endorsed, standardized protocols and recommendations for interpreting RNA assay data