RNA methyltransferase SPOUT1/CENP-32 links mitotic spindle organization with the neurodevelopmental disorder SpADMiSS.

SPOUT1/CENP-32 encodes a putative SPOUT RNA methyltransferase previously identified as a mitotic chromosome associated protein. SPOUT1/CENP-32 depletion leads to centrosome detachment from the spindle poles and chromosome misalignment. Aided by gene matching platforms, we identified 24 individuals with neurodevelopmental delays from 18 families with bi-allelic variants in SPOUT1/CENP-32 detected by exome/genome sequencing. Zebrafish spout1/cenp-32 mutants showed reduction in larval head size with concomitant apoptosis likely associated with altered cell cycle progression. In vivo complementation assays in zebrafish indicated that SPOUT1/CENP-32 missense variants identified in humans are pathogenic. Crystal structure analysis of SPOUT1/CENP-32 revealed that most disease-associated missense variants mapped to the catalytic domain. Additionally, SPOUT1/CENP-32 recurrent missense variants had reduced methyltransferase activity in vitro and compromised centrosome tethering to the spindle poles in human cells. Thus, SPOUT1/CENP-32 pathogenic variants cause an autosomal recessive neurodevelopmental disorder: SpADMiSS ( SPOUT1 Associated Development delay Microcephaly Seizures Short stature) underpinned by mitotic spindle organization defects and consequent chromosome segregation errors.

Opportunities, barriers, and recommendations in down syndrome research.

BACKGROUND: Recent advances in medical care have increased life expectancy and improved the quality of life for people with Down syndrome (DS). These advances are the result of both pre-clinical and clinical research but much about DS is still poorly understood. In 2020, the NIH announced their plan to update their DS research plan and requested input from the scientific and advocacy community. OBJECTIVE: The National Down Syndrome Society (NDSS) and the LuMind IDSC Foundation worked together with scientific and medical experts to develop recommendations for the NIH research plan. METHODS: NDSS and LuMind IDSC assembled over 50 experts across multiple disciplines and organized them in eleven working groups focused on specific issues for people with DS. RESULTS: This review article summarizes the research gaps and recommendations that have the potential to improve the health and quality of life for people with DS within the next decade. CONCLUSIONS: This review highlights many of the scientific gaps that exist in DS research. Based on these gaps, a multidisciplinary group of DS experts has made recommendations to advance DS research. This paper may also aid policymakers and the DS community to build a comprehensive national DS research strategy.

Patterns of Dietary Supplement Use in Children with Down Syndrome.

OBJECTIVE: To determine the frequency of dietary supplement use for children with Down syndrome, and to obtain additional descriptive data regarding the age of initial treatment, cost, perceived benefits, and disclosure of use to the pediatrician. STUDY DESIGN: An anonymous questionnaire in English and Spanish was created for parents of children under age 18 years with Down syndrome. Surveys were completed in our clinic, or accessed on a number of Down syndrome-related websites. RESULTS: A total of 1167 responses were completed and analyzed. Forty nine percent of responders currently/previously gave their child supplement(s). The average child received 3 supplements (ranging from 1-18). Although Nutrivene, curcumin, and green tea extract were most common, over 150 different products were reported. Supplementation began most often in infancy, generally between age 4 and 6 months. Average cost was $90.53/month. Overall, 87% of users noted improvement, mainly in speech, immunity, and attention; 17% reported side-effects, predominantly gastrointestinal disturbance. Lack of improvement and cost were the main reasons for discontinuation. Most parents learned of supplements through a parent group or friend. In almost 20%, the pediatrician was unaware of the supplement use. CONCLUSIONS: Almost one-half of parents surveyed administer or have administered supplement(s) to their children with Down syndrome. Many of the supplements have concerning ingredient profiles and are given to children too young to articulate potential ill effects. Providers need to be aware of these products and question families about their use.

Intellectual disability and epilepsy due to the K/L-mediated Xq28 duplication: Further evidence of a distinct, dosage-dependent phenotype.

Copy number variants of the X-chromosome are a common cause of X-linked intellectual disability in males. Duplication of the Xq28 band has been known for over a decade to be the cause of the Lubs X-linked Mental Retardation Syndrome (OMIM 300620) in males and this duplication has been narrowed to a critical region containing only the genes MECP2 and IRAK1. In 2009, four families with a distal duplication of Xq28 not including MECP2 and mediated by low-copy repeats (LCRs) designated "K" and "L" were reported with intellectual disability and epilepsy. Duplication of a second more distal region has been described as the cause of the Int22h-1/Int22h-2 Mediated Xq28 Duplication Syndrome, characterized by intellectual disability, psychiatric problems, and recurrent infections. We report two additional families possessing the K/L-mediated Xq28 duplication with affected males having intellectual disability and epilepsy similar to the previously reported phenotype. To our knowledge, this is the second cohort of individuals to be reported with this duplication and therefore supports K/L-mediated Xq28 duplications as a distinct syndrome.

Preoperative evaluation and comprehensive risk assessment for children with Down syndrome.

Down syndrome is a common chromosome disorder affecting all body systems. This creates unique physiologic concerns that can affect safety during anesthesia and surgery. Little consensus exists, however, on the best way to evaluate children with Down syndrome in preparation for surgery. We review a number of salient topics affecting these children in the perioperative period, including cervical spine instability, cardiovascular abnormalities, pulmonary hypertension, upper airway obstruction, hematologic disturbances, prematurity, low birth weight, and the use of supplements and alternative therapies. Recommendations include obtaining a complete blood count to detect an increased risk for bleeding or stroke, and cardiology evaluation to identify patients with pulmonary hypertension, as well as undiagnosed or residual heart disease. Pediatric cardiac anesthesiologists and intensivists should be involved as needed. The potential for cervical spine instability should be considered, and the anesthesiologist may wish to have several options available both for the medications and equipment used. The child's family should always be asked if he or she is on any nutritional supplements, as some products marketed to families may have secondary effects such as inhibition of platelet function. Using this evaluation in presurgical planning will allow physicians to better consider the individual circumstances for their patients with Down syndrome. Our goal was to optimize patient safety by choosing the most appropriate setting and perioperative personnel, and to mitigate those risk factors amenable to intervention.

Mutations of ARX are associated with striking pleiotropy and consistent genotype-phenotype correlation.

We recently identified mutations of ARX in nine genotypic males with X-linked lissencephaly with abnormal genitalia (XLAG), and in several female relatives with isolated agenesis of the corpus callosum (ACC). We now report 13 novel and two recurrent mutations of ARX, and one nucleotide change of uncertain significance in 20 genotypic males from 16 families. Most had XLAG, but two had hydranencephaly and abnormal genitalia, and three males from one family had Proud syndrome or ACC with abnormal genitalia. We obtained detailed clinical information on all 29 affected males, including the nine previously reported subjects. Premature termination mutations consisting of large deletions, frameshifts, nonsense mutations, and splice site mutations in exons 1 to 4 caused XLAG or hydranencephaly with abnormal genitalia. Nonconservative missense mutations within the homeobox caused less severe XLAG, while conservative substitution in the homeodomain caused Proud syndrome. A nonconservative missense mutation near the C-terminal aristaless domain caused unusually severe XLAG with microcephaly and mild cerebellar hypoplasia. In addition, several less severe phenotypes without malformations have been reported, including mental retardation with cryptogenic infantile spasms (West syndrome), other seizure types, dystonia or autism, and nonsyndromic mental retardation. The ARX mutations associated with these phenotypes have included polyalanine expansions or duplications, missense mutations, and one deletion of exon 5. Together, the group of phenotypes associated with ARX mutations demonstrates remarkable pleiotropy, but also comprises a nearly continuous series of developmental disorders that begins with hydranencephaly, lissencephaly, and agenesis of the corpus callosum, and ends with a series of overlapping syndromes with apparently normal brain structure.