Heterozygous variants in CTR9, which encodes a major component of the PAF1 complex, are associated with a neurodevelopmental disorder.

PURPOSE: CTR9 is a subunit of the PAF1 complex (PAF1C) that plays a crucial role in transcription regulation by binding CTR9 to RNA polymerase II. It is involved in transcription-coupled histone modification through promoting H3K4 and H3K36 methylation. We describe the clinical and molecular studies in 13 probands, harboring likely pathogenic CTR9 missense variants, collected through GeneMatcher. METHODS: Exome sequencing was performed in all individuals. CTR9 variants were assessed through 3-dimensional modeling of the activated human transcription complex Pol II-DSIF-PAF-SPT6 and the PAF1/CTR9 complex. H3K4/H3K36 methylation analysis, mitophagy assessment based on tetramethylrhodamine ethyl ester perchlorate immunofluorescence, and RNA-sequencing in skin fibroblasts from 4 patients was performed. RESULTS: Common clinical findings were variable degrees of intellectual disability, hypotonia, joint hyperlaxity, speech delay, coordination problems, tremor, and autism spectrum disorder. Mild dysmorphism and cardiac anomalies were less frequent. For 11 CTR9 variants, de novo occurrence was shown. Three-dimensional modeling predicted a likely disruptive effect of the variants on local CTR9 structure and protein interaction. Additional studies in fibroblasts did not unveil the downstream functional consequences of the identified variants. CONCLUSION: We describe a neurodevelopmental disorder caused by (mainly) de novo variants in CTR9, likely affecting PAF1C function.

The first patient with tandem duplication of 6q14q16: Molecular and phenotypic characterization.

Duplications of the long arm of chromosome 6 have been previously reported in a limited number of patients; however, most reported duplications encompass regions of chromosome 6 distal to band q21. Duplications restricted to the proximal portion of 6q are rare. We report an 8-year-old male with a 16.4 megabase (Mb) tandem duplication of chromosome 6q14.1q16.1 (chr6:78950191-95395865; hg19) who exhibited dysmorphic facial features, seizures, global developmental delay, intellectual disability, autism spectrum disorder, sensorineural hearing loss, and immune deficiency. This patient refines and potentially expands the current, poorly-characterized phenotype associated with duplication of this proximal 6q region. We recommend a low threshold for a hearing evaluation beyond newborn screening and for pursuing an immune work-up in patients with similar 6q duplications. © 2016 Wiley Periodicals, Inc.

Pre-analytic decrease of phenylalanine in plasma of patients with phenylketonuria treated with pegvaliase.

Treatment of phenylketonuria (PKU) has evolved since the initial introduction of a phenylalanine (Phe) restricted diet. The most recent option for adults affected with PKU is treatment with an alternate enzyme, phenylalanine ammonia lyase (PAL), that metabolizes excess Phe. Proper management of all patients with PKU relies on accurate measurement of Phe levels in blood, to comply with guidance intended to minimize the neurological symptoms. Recently, our laboratory was notified of discrepant results for a patient with PKU who is treated with pegvaliase. Two specimens were collected at the same time but yielded unexpectedly different Phe concentrations. After exclusion of specimen mix-ups or analytical errors, we suspected that there was residual pegvaliase activity in the specimens continuing to degrade Phe after collection. To investigate this possibility, we performed spiking studies that showed the degradation of Phe over time at ambient temperatures. Sample preparation by protein crash appears to deactivate pegvaliase and prevents further Phe degradation. However, because pegvaliase deactivation would be required immediately following blood collection, appropriate mitigation measures must be implemented, including stringent pre-analytical requirements, alternate sample matrices such as dried blood spots, or point of care testing. Until then, health care professionals need to be cautious in their interpretation of Phe levels in their patients with PKU that are treated with pegvaliase.

Multi-center implementation of rapid whole genome sequencing provides additional evidence of its utility in the pediatric inpatient setting.

Objective: Multi-center implementation of rapid whole genome sequencing with assessment of the clinical utility of rapid whole genome sequencing (rWGS), including positive, negative and uncertain results, in admitted infants with a suspected genetic disease. Study design: rWGS tests were ordered at eight hospitals between November 2017 and April 2020. Investigators completed a survey of demographic data, Human Phenotype Ontology (HPO) terms, test results and impacts of results on clinical care. Results: A total of 188 patients, on general hospital floors and intensive care unit (ICU) settings, underwent rWGS testing. Racial and ethnic characteristics of the tested infants were broadly representative of births in the country at large. 35% of infants received a diagnostic result in a median of 6 days. The most common HPO terms for tested infants indicated an abnormality of the nervous system, followed by the cardiovascular system, the digestive system, the respiratory system and the head and neck. Providers indicated a major change in clinical management because of rWGS for 32% of infants tested overall and 70% of those with a diagnostic result. Also, 7% of infants with a negative rWGS result and 23% with a variant of unknown significance (VUS) had a major change in management due to testing. Conclusions: Our study demonstrates that the implementation of rWGS is feasible across diverse institutions, and provides additional evidence to support the clinical utility of rWGS in a demographically representative sample of admitted infants and includes assessment of the clinical impact of uncertain rWGS results in addition to both positive and negative results.

Reduction in Newborn Screening False Positive Results Following a New Collection Protocol: a Quality Improvement Project.

OBJECTIVE: Premature infants are known to have a higher rate of false positive newborn screening (NBS) results, with TPN as a contributing factor. The purpose of this quality improvement (QI) project is to reduce false positive NBS results via a TPN interruption protocol. METHODS: A multidisciplinary team reviewed the literature and developed a new NBS collection protocol, which was implemented in 2 periods. In period 1, TPN was interrupted for 4 hours before NBS sample collection and initiation of carnitine supplements was avoided. In period 2, TPN was interrupted for 6 hours for infants birth weight (BW) < 1000 g, carnitine supplementation continued to be avoided. The rates of false positives NBS results were compared pre- and post-interventions in periods 1 and 2. RESULTS: Four hundred twelve neonates were evaluated prior to implementation of this QI project (July 2013-June 2014) and 414 during period 1 intervention (July 2014-June 2016). False positive results decreased from 20.6% to 11.4% (p < 0.001) among all BW categories following the 4-hour TPN interruption. The rate of false positives was further reduced among infants < 1000 g (p = 0.035) in period 2 (n = 112), including a significant reduction in false positive results with elevated amino acid profiles (p = 0.005). CONCLUSIONS: The implementation of a strict NBS collection protocol reduced false positive NBS results, which potentially can improve patient care by reducing unnecessary laboratory draws, pain, and parental anxiety. Interruption of TPN for 6 hours was significant in reducing NBS false positive results in neonates < 1000 g.

Mutations in PDLIM5 are rare in dilated cardiomyopathy but are emerging as potential disease modifiers.

BACKGROUND: A causal genetic mutation is found in 40% of families with dilated cardiomyopathy (DCM), leaving a large percentage of families genetically unsolved. This prevents adequate counseling and clear recommendations in these families. We aim to identify novel genes or modifiers associated with DCM. METHODS: We performed computational ranking of human genes based on coexpression with a predefined set of genes known to be associated with DCM, which allowed us to prioritize gene candidates for their likelihood of being involved in DCM. Top candidates will be checked for variants in the available whole-exome sequencing data of 142 DCM patients. RNA was isolated from cardiac biopsies to investigate gene expression. RESULTS: PDLIM5 was classified as the top candidate. An interesting heterozygous variant (189_190delinsGG) was found in a DCM patient with a known pathogenic truncating TTN-variant. The PDLIM5 loss-of-function (LoF) variant affected all cardiac-specific isoforms of PDLIM5 and no LoF variants were detected in the same region in a control cohort of 26,000 individuals. RNA expression of PDLIM5 and its direct interactors (MYOT, LDB3, and MYOZ2) was increased in cardiac tissue of this patient, indicating a possible compensatory mechanism. The PDLIM5 variant cosegregated with the TTN-variant and the phenotype, leading to a high disease penetrance in this family. A second patient was an infant with a homozygous 10 kb-deletion of exon 2 in PDLIM5 resulting in early-onset cardiac disease, showing the importance of PDLIM5 in cardiac function. CONCLUSIONS: Heterozygous PDLIM5 variants are rare and therefore will not have a major contribution in DCM. Although they likely play a role in disease development as this gene plays a major role in contracting cardiomyocytes and homozygous variants lead to early-onset cardiac disease. Other environmental and/or genetic factors are probably necessary to unveil the cardiac phenotype in PDLIM5 mutation carriers.

Untreated PKU Patients without Intellectual Disability: What Do They Teach Us?

Phenylketonuria (PKU) management is aimed at preventing neurocognitive and psychosocial dysfunction by keeping plasma phenylalanine concentrations within the recommended target range. It can be questioned, however, whether universal plasma phenylalanine target levels would result in optimal neurocognitive outcomes for all patients, as similar plasma phenylalanine concentrations do not seem to have the same consequences to the brain for each PKU individual. To better understand the inter-individual differences in brain vulnerability to high plasma phenylalanine concentrations, we aimed to identify untreated and/or late-diagnosed PKU patients with near-normal outcome, despite high plasma phenylalanine concentrations, who are still alive. In total, we identified 16 such cases. While intellectual functioning in these patients was relatively unaffected, they often did present other neurological, psychological, and behavioral problems. Thereby, these "unusual" PKU patients show that the classical symptomatology of untreated or late-treated PKU may have to be rewritten. Moreover, these cases show that a lack of intellectual dysfunction despite high plasma phenylalanine concentrations does not necessarily imply that these high phenylalanine concentrations have not been toxic to the brain. Also, these cases may suggest that different mechanisms are involved in PKU pathophysiology, of which the relative importance seems to differ between patients and possibly also with increasing age. Further research should aim to better distinguish PKU patients with respect to their cerebral effects to high plasma phenylalanine concentrations.

De novo three-way chromosome translocation 46,XY,t(4;6;21)(p16;p21.1;q21) in a male with cleidocranial dysplasia.

Cleidocranial dysplasia (CCD) is an autosomal dominant skeletal dysplasia associated with cranial, clavicular, and dental anomalies. It is caused by mutations in the RUNX2 gene, which encodes an osteoblast-specific transcription factor and maps to chromosome 6p21. We report clinical and molecular cytogenetic studies in a patient with clinical features of CCD including wormian bones, delayed fontanel closure, hypoplastic clavicles and pubic rami, and supernumerary dentition. Additional abnormalities of bone growth and connective tissue, including easy bruisability, scarring, bleeding, joint hypermobility, and developmental delay were also observed. Molecular cytogenetic studies identified a de novo apparently balanced three-way translocation 46,XY,t(4;6;21)(p16;p21.1;q21). Further mapping revealed the breakpoint on 6p21 to be approximately 50 kb upstream of exon 1 of the RUNX2 gene, with RUNX2 being intact on the derivative chromosome 6. We hypothesize that the proband's CCD has arisen from disruption of the developmentally regulated gene RUNX2 at the 6p21 breakpoint, due to a position effect mutation which may have altered the expression of the gene. Further studies might unravel a new regulatory element for RUNX2.

Adoptees' Pursuit of Genomic Testing to Fill Gaps in Family Health History and Reduce Healthcare Disparity.

In the symposium of stories by adoptees who have faced health issues without family health history information, genomic testing is considered as a potentially life-saving means for adoptees to obtain family medical information. The authors share feelings of loss, frustration in healthcare settings, fear of unknown genetic susceptibility to disease, desire for knowledge and self-empowerment in medical decision making, and uncertainty about the utility of genomic testing. Adoptees may pursue ancestry testing, genetic genealogy to find biological relatives, and medical genomic testing. They may choose direct-to-consumer testing because of its affordability and accessibility. Adopted persons are gaining support from healthcare professionals in their pursuit of genomic testing. The National Society of Genetic Counselors' position statement regarding genetic testing and adoption "supports consideration of genetic testing, including genome-wide testing, for adopted adults." However, predictive genomic testing of children in the adoption process is not recommended by the NSGC unless testing may affect childhood medical management. The American Society of Human Genetics and the American College of Medical Genetics and Genomics similarly recommend that genetic testing of children in the adoption process be limited to diagnostic testing for conditions for which there is timely preventative or therapeutic intervention. Going forward, there is responsibility and opportunity for national genetics and genomics societies and healthcare systems to hone their practice guidelines for genomic testing for adoptees. A successful approach will include evidence-based guidelines for genomic testing, inclusion of genetic counseling before and after testing, and return of genomic test results to adoptees' medical homes.

Can untreated PKU patients escape from intellectual disability? A systematic review.

BACKGROUND: Phenylketonuria (PKU) is often considered as the classical example of a genetic disorder in which severe symptoms can nowadays successfully be prevented by early diagnosis and treatment. In contrast, untreated or late-treated PKU is known to result in severe intellectual disability, seizures, and behavioral disturbances. Rarely, however, untreated or late-diagnosed PKU patients with high plasma phenylalanine concentrations have been reported to escape from intellectual disability. The present study aimed to review published cases of such PKU patients. METHODS: To this purpose, we conducted a literature search in PubMed and EMBASE up to 8th of September 2017 to identify cases with 1) PKU diagnosis and start of treatment after 7 years of age; 2) untreated plasma phenylalanine concentrations ≥1200 µmol/l; and 3) IQ ≥80. Literature search, checking reference lists, selection of articles, and extraction of data were performed by two independent researchers. RESULTS: In total, we identified 59 published cases of patients with late-diagnosed PKU and unexpected favorable outcome who met the inclusion criteria. Although all investigated patients had intellectual functioning within the normal range, at least 19 showed other neurological, psychological, and/or behavioral symptoms. CONCLUSIONS: Based on the present findings, the classical symptomatology of untreated or late-treated PKU may need to be rewritten, not only in the sense that intellectual dysfunction is not obligatory, but also in the sense that intellectual functioning does not (re)present the full picture of brain damage due to high plasma phenylalanine concentrations. Further identification of such patients and additional analyses are necessary to better understand these differences between PKU patients.

Chromosome 2q37 deletion: clinical and molecular aspects.

Terminal deletions of chromosome 2 with breakpoints at or within band 2q37, ranging from visible abnormalities to cryptic, subtelomeric deletions, have been recognized with increasing frequency among children with mild-moderate mental retardation, characteristic facial appearance, and behavioral manifestations which often place them on the autism spectrum. The stereotypic facial characteristics include prominent forehead, thin, highly arched eyebrows, depressed nasal bridge, full cheeks, deficient nasal alae and prominent columella, thin upper lip, and various minor anomalies of the pinnae. Abnormal nipples, including inverted nipples, have been reported in a number of cases. CNS, ocular, cardiac, gastrointestinal, renal, and other GU anomalies have been noted in nearly one-third of patients. Of note, coarctation or hypoplasia of the aorta has been described in several affected children. Wilms tumor, renal dysplasia, and tracheomalacia have been reported only with the most proximal breakpoint at band 2q37.1 while a range of GI anomalies, pyloric stenosis, and diaphragmatic defects have been reported with breakpoints throughout the region. A subset of patients with the most distal deletion present phenotypic features which mimic Albright hereditary osteodystrophy (AHO). In addition to the AHO-like phenotype, later onset findings include seizures and cystic kidneys. Timely diagnosis of this recognizable syndrome provides a basis for genetic counseling, appropriate surveillance, and intervention, and avoids unnecessary and expensive diagnostic testing.

Mitochondrial myopathy, sideroblastic anemia, and lactic acidosis: an autosomal recessive syndrome in Persian Jews caused by a mutation in the PUS1 gene.

We report the seventh case of autosomal recessive inherited mitochondrial myopathy, lactic acidosis, and sideroblastic anemia The patient, a product of consanguineous Persian Jews, had the association of mental retardation, dysmorphic features, lactic acidosis, myopathy, and sideroblastic anemia. Muscle biopsy demonstrated low activity of complexes 1 and 4 of the respiratory chain. Electron microscopy revealed paracrystalline inclusions in most mitochondria. Southern blot of the mitochondrial DNA did not show any large-scale rearrangements. The patient was found to be homozygous for the 656C-->T mutation in the pseudouridine synthase 1 gene (PUS1). Mitochondrial myopathy, lactic acidosis, and sideroblastic anemia is an oxidative phosphorylation disorder causing sideroblastic anemia, myopathy, and, in some cases, mental retardation that is due to mutations in the nuclear-encoded PUS1 gene. This finding provides additional evidence that mitochondrial ribonucleic acid modification impacts the phenotypic expression of oxidative phosphorylation disorders.

De novo mutation in POLG leads to haplotype insufficiency and Alpers syndrome.

Mutations in POLG are a major contributor to pediatric and adult mitochondrial diseases. However, the consequences of many POLG mutations are not well understood. We investigated the molecular cause of Alpers syndome in a patient harboring the POLG mutations A467T in trans with c.2157+5_+6 gc-->ag in intron 12. Analysis of transcripts arising from the c.2157+5_+6 gc-->ag allele revealed alternative splicing with an insertion of 30 intronic nucleotides leading to a premature termination codon. These transcripts were subsequently removed through nonsense-mediated decay, leading to haplotype insufficiency due to expression of the A467T allele and decreased expression of the c.2157+5_+6 gc-->ag allele, which is likely responsible for the Alpers syndrome phenotype.

Mitochondrial myopathy and sideroblastic anemia.

We report four new cases of mitochondrial myopathy and sideroblastic anemia (MSA). Hallmark features of MSA include progressive exercise intolerance during childhood, onset of sideroblastic anemia around adolescence, basal lactic acidemia, and mitochondrial myopathy. Autosomal recessive inheritance of MSA in the family we describe is assumed due to the presence of two affected sibling pairs, unaffected parents, an unaffected sibling, and parental consanguinity. The nuclear families we describe are paternally related and originate from the same Iranian city as a family with MSA described by [Inbal et al., 1995]. These families provide an opportunity to clarify the molecular basis of tissue specific expression of mitochondrial disorders.

Missense mutation in pseudouridine synthase 1 (PUS1) causes mitochondrial myopathy and sideroblastic anemia (MLASA).

Mitochondrial myopathy and sideroblastic anemia (MLASA) is a rare, autosomal recessive oxidative phosphorylation disorder specific to skeletal muscle and bone marrow. Linkage analysis and homozygosity testing of two families with MLASA localized the candidate region to 1.2 Mb on 12q24.33. Sequence analysis of each of the six known genes in this region, as well as four putative genes with expression in bone marrow or muscle, identified a homozygous missense mutation in the pseudouridine synthase 1 gene (PUS1) in all patients with MLASA from these families. The mutation is the only amino acid coding change in these 10 genes that is not a known polymorphism, and it is not found in 934 controls. The amino acid change affects a highly conserved amino acid, and appears to be in the catalytic center of the protein, PUS1p. PUS1 is widely expressed, and quantitative expression analysis of RNAs from liver, brain, heart, bone marrow, and skeletal muscle showed elevated levels of expression in skeletal muscle and brain. We propose deficient pseudouridylation of mitochondrial tRNAs as an etiology of MLASA. Identification of the pathophysiologic pathways of the mutation in these families may shed light on the tissue specificity of oxidative phosphorylation disorders.

Gene responsible for mitochondrial myopathy and sideroblastic anemia (MSA) maps to chromosome 12q24.33.

Mitochondrial myopathy and sideroblastic anemia (MSA) is a rare autosomal recessive disorder of oxidative phosphorylation and iron metabolism. Individuals with MSA present with weakness and anemia in late childhood and may become dependent on blood transfusions. Recently, we reported affected sibling pairs from a Jewish-Iranian kindred living in the US [Casas and Fischel-Ghodsian, 2003]. A genome scan and fine mapping of DNA from this family revealed homozygous alleles in the affected individuals, and a multipoint logarithm of the odds (lod) score of 3.3, within 2.3 mb of chromosome 12q24.33. Previously, Inbal et al. [1995: Am J Med Genet 55:372-378] described siblings with a similar clinical phenotype who lived in Israel but originated from the same Iranian town as the US family. Focused analysis of DNA from the Israeli family confirmed the presence of identical, homozygous alleles in the affected of the US and Israeli families within 1.2 mb of chromosome 12q24.33. Combined multipoint linkage analysis revealed a maximum lod score of 5.41 at the 132 cM position of chromosome 12. Therefore, in these two families of Jewish-Iranian descent, a disease gene for MSA maps to a 1.2 mb region of chromosome 12q24.33. This region contains 6 well described genes (SFRS8, MMP17, ULK1, PUS1, EP400, and GALNT9) and at least 15 additional putative transcripts. The known genes are expressed in multiple tissues and lack a function specific to mitochondria, making none an obvious candidate. The eventual identification of the disease gene in MSA is expected to provide insight into the tissue specificity and phenotypic variability of mitochondrial disease.

Mitochondrial myopathy and sideroblastic anemia (MSA) is a rare autosomal recessive disorder of oxidative phosphorylation and iron metabolism. Individuals with MSA present with weakness and anemia in late childhood and may become dependent on blood transfusions. Recently, we reported affected sibling pairs from a Jewish-Iranian kindred living in the US [Casas and Fischel-Ghodsian, 2003]. A genome scan and fine mapping of DNA from this family revealed homozygous alleles in the affected individuals, and a multipoint logarithm of the odds (lod) score of 3.3, within 2.3 mb of chromosome 12q24.33. Previously, Inbal et al. [1995: Am J Med Genet 55:372-378] described siblings with a similar clinical phenotype who lived in Israel but originated from the same Iranian town as the US family. Focused analysis of DNA from the Israeli family confirmed the presence of identical, homozygous alleles in the affected of the US and Israeli families within 1.2 mb of chromosome 12q24.33. Combined multipoint linkage analysis revealed a maximum lod score of 5.41 at the 132 cM position of chromosome 12. Therefore, in these two families of Jewish-Iranian descent, a disease gene for MSA maps to a 1.2 mb region of chromosome 12q24.33. This region contains 6 well described genes (SFRS8, MMP17, ULK1, PUS1, EP400, and GALNT9) and at least 15 additional putative transcripts. The known genes are expressed in multiple tissues and lack a function specific to mitochondria, making none an obvious candidate. The eventual identification of the disease gene in MSA is expected to provide insight into the tissue specificity and phenotypic variability of mitochondrial disease.

Chromosome 2q terminal deletion: report of 6 new patients and review of phenotype-breakpoint correlations in 66 individuals.

We report a new patient with terminal deletion of chromosome 2 with breakpoint at 2q36 and five additional new patients with 2q terminal deletion with breakpoint at 2q37. Hemidiaphragmatic hernia is a novel finding in one patient with a breakpoint at 2q37.1. In comparing these patients to 60 previously reported individuals with 2q terminal deletions, certain physical abnormalities are loosely associated with positions of breakpoint. For example, facial features (e.g., prominent forehead, depressed nasal bridge, and dysmorphic ears and nose), short stature, and short hands and feet were frequent in patients with breakpoints at or proximal to 2q37.3. Reports of horseshoe kidney and Wilms tumor were limited to patients with a breakpoint at 2q37.1, and structural brain anomalies and tracheal anomalies were reported only in patients with breakpoints at or proximal to 2q37.1. Cleft palate was reported only in patients with the most proximal breakpoints (2q36 or 2q35). Neurological effects including developmental delay, mental retardation, autistic-like behavior, and hypotonia were typical in this patient population but did not stratify in severity according to breakpoint. Terminal deletion of the long arm of chromosome 2 should be considered in the infant with marked hypotonia, poor feeding, gastroesophageal reflux, and growth delay, and the older child with developmental delay, autistic behavior, and the characteristic facial and integumentary features described herein. Assignment of clinical features to specific breakpoints and refinement of predictive value may be useful in counseling.