ITPR1-associated spinocerebellar ataxia with craniofacial features-additional evidence for germline mosaicism.

Inositol 1,4,5-triphosphate receptor type 1 (ITPR1) is an endoplasmic reticulum-bound intracellular inositol triphosphate receptor involved in the regulation of intracellular calcium. Pathogenic variants in ITPR1 are associated with spinocerebellar ataxia (SCA) types 15/16 and 29 and have recently been implicated in a facial microsomia syndrome. In this report, we present a family with three affected individuals found to have a heterozygous missense c.800C > T (predicted p.Thr267Met) who present clinically with a SCA29-like syndrome. All three individuals presented with varying degrees of ataxia, developmental delay, and apparent intellectual disability, as well as craniofacial involvement-an uncommon finding in patients with SCA29. The variant was identified using clinical exome sequencing and validated with Sanger sequencing. It is presumed to be inherited via parental germline mosaicism. We present our findings to provide additional evidence for germline mosaic inheritance of SCA29, as well as to expand the clinical phenotype of the syndrome.

Expanding the phenotypic spectrum of NAA10-related neurodevelopmental syndrome and NAA15-related neurodevelopmental syndrome.

Amino-terminal (Nt-) acetylation (NTA) is a common protein modification, affecting 80% of cytosolic proteins in humans. The human essential gene, NAA10, encodes for the enzyme NAA10, which is the catalytic subunit in the N-terminal acetyltransferase A (NatA) complex, also including the accessory protein, NAA15. The full spectrum of human genetic variation in this pathway is currently unknown. Here we reveal the genetic landscape of variation in NAA10 and NAA15 in humans. Through a genotype-first approach, one clinician interviewed the parents of 56 individuals with NAA10 variants and 19 individuals with NAA15 variants, which were added to all known cases (N = 106 for NAA10 and N = 66 for NAA15). Although there is clinical overlap between the two syndromes, functional assessment demonstrates that the overall level of functioning for the probands with NAA10 variants is significantly lower than the probands with NAA15 variants. The phenotypic spectrum includes variable levels of intellectual disability, delayed milestones, autism spectrum disorder, craniofacial dysmorphology, cardiac anomalies, seizures, and visual abnormalities (including cortical visual impairment and microphthalmia). One female with the p.Arg83Cys variant and one female with an NAA15 frameshift variant both have microphthalmia. The frameshift variants located toward the C-terminal end of NAA10 have much less impact on overall functioning, whereas the females with the p.Arg83Cys missense in NAA10 have substantial impairment. The overall data are consistent with a phenotypic spectrum for these alleles, involving multiple organ systems, thus revealing the widespread effect of alterations of the NTA pathway in humans.

Phenotypic variability and gastrointestinal manifestations/interventions for growth in NAA10-related neurodevelopmental syndrome.

Our study of 61 children with NAA10-related neurodevelopmental syndrome, an X-linked disorder due to NAA10 gene variants, demonstrated a high prevalence of growth failure, with weight and height percentiles often in the failure-to-thrive diagnostic range; however, dramatic weight fluctuations and phenotypic variability is evidenced in the growth parameters of this population. Although never previously explored in depth, the gastrointestinal pathology associated with NAA10-related neurodevelopmental syndrome includes feeding difficulties in infancy, dysphagia, GERD/silent reflux, vomiting, constipation, diarrhea, bowel incontinence, and presence of eosinophils on esophageal endoscopy, in order from most to least prevalent. Additionally, the gastrointestinal symptom profile for children with this syndrome has been expanded to include eosinophilic esophagitis, cyclic vomiting syndrome, Mallory Weiss tears, abdominal migraine, esophageal dilation, and subglottic stenosis. Although the exact cause of poor growth in NAA10-related neurodevelopmental syndrome probands is unclear and the degree of contribution to this problem by GI symptomatology remains uncertain, an analysis including nine G-tube or GJ-tube fed probands demonstrates that G/GJ-tubes are overall efficacious with respect to improvements in weight gain and caregiving. The choice to insert a gastrostomy or gastrojejunal tube to aid with weight gain is often a challenging decision to make for parents, who may alternatively choose to rely on oral feeding, caloric supplementation, calorie tracking, and feeding therapy. In this case, if NAA10-related neurodevelopmental syndrome children are not tracking above the failure to thrive (FTT) range past 1 year of age despite such efforts, the treating physicians should be consulted regarding possibly undergoing G-tube placement to avoid prolonged growth failure. If G-tubes are not immediately inducing weight gain after insertion, recommendations could include altering formula, increasing caloric input, or exchanging a G-tube for a GJ-tube by means of a minimally invasive procedure.

Autosomal recessive SLC30A9 variants in a proband with a cerebrorenal syndrome and no parental consanguinity.

An SLC30A9-associated cerebrorenal syndrome was first reported in consanguineous Bedouin kindred by Perez et al. in 2017. Although the function of the gene has not yet been fully elucidated, it may be implicated in Wnt signaling and nuclear regulation, as well as in cell and mitochondrial zinc regulation. In this research report, we present a female proband with two distinct, inherited autosomal recessive loss-of-function SLC30A9 variants from unrelated parents. To our knowledge, this is the first reported case of a possible SLC30A9-associated cerebrorenal syndrome in a nonconsanguineous family. Furthermore, a limited statistical analysis was conducted to identify possible allele frequency differences between populations. Our findings provide further support for an SLC30A9-associated cerebrorenal syndrome and may help clarify the gene's function through its possible disease association.