Glycogen storage disease type 1a in the Ohio Amish

Glycogen storage disease type 1a (GSD1a) is an inborn error of glucose metabolism characterized by fasting hypoglycemia, hepatomegaly, and growth failure. Late complications include nephropathy and hepatic adenomas. We conducted a retrospective observational study on a cohort of Amish patients with GSD1a. A total of 15 patients cared for at a single center, with a median age of 9.9 years (range 0.25–24 years) were included. All patients shared the same founder variant in GCPC c.1039 C > T. The phenotype of this cohort demonstrated good metabolic control with median cohort triglyceride level slightly above normal, no need for continuous overnight feeds, and a higher quality of life compared to a previous GSD cohort. The most frequent complications were oral aversion, gross motor delay, and renal hyperfiltration. We discuss our unique care delivery at a single center that cares for Amish patients with inherited disorders.

Elucidating the clinical spectrum and molecular basis of HYAL2 deficiency

PURPOSE

We previously defined biallelic HYAL2 variants causing a novel disorder in 2 families, involving orofacial clefting, facial dysmorphism, congenital heart disease, and ocular abnormalities, with Hyal2 knockout mice displaying similar phenotypes. In this study, we better define the phenotype and pathologic disease mechanism.

METHODS

Clinical and genomic investigations were undertaken alongside molecular studies, including immunoblotting and immunofluorescence analyses of variant/wild-type human HYAL2 expressed in mouse fibroblasts, and in silico modeling of putative pathogenic variants.

RESULTS

Ten newly identified individuals with this condition were investigated, and they were associated with 9 novel pathogenic variants. Clinical studies defined genotype-phenotype correlations and confirmed a recognizable craniofacial phenotype in addition to myopia, cleft lip/palate, and congenital cardiac anomalies as the most consistent manifestations of the condition. In silico modeling of missense variants identified likely deleterious effects on protein folding. Consistent with this, functional studies indicated that these variants cause protein instability and a concomitant cell surface absence of HYAL2 protein.

CONCLUSION

These studies confirm an association between HYAL2 alterations and syndromic cleft lip/palate, provide experimental evidence for the pathogenicity of missense alleles, enable further insights into the pathomolecular basis of the disease, and delineate the core and variable clinical outcomes of the condition.

Vaccination patterns of the northeast Ohio Amish revisited

OBJECTIVES

The Holmes County Amish have low vaccination rates, an increasingly diverse population, and have an increased incidence of certain inherited diseases. The objectives were to evaluate; the rate and influences of vaccine hesitancy compared to a decade ago, vaccination patterns between Amish affiliations, vaccine practices of Amish special needs children, and the Amish's acceptance of a COVID-19 vaccine.

STUDY DESIGN

In April of 2020, a survey assessing vaccination patterns and beliefs were mailed to 1000 Amish families, including ultra-conservative Amish sects and special needs families.

RESULTS

The response rate was 39%. Among 391 respondents, 59% did not vaccinate their children, compared to only 14% that refused all vaccinations reported by Wenger et al in the same community only a decade ago. The ultra-conservative Amish rejected vaccines more often. Amish special needs children were more likely to receive vaccines than healthy Amish children. 75% responded they would reject a COVID-19 vaccine. Fear of adverse effects was the most common reason to reject vaccines. Families that accepted vaccines were more likely to cite a healthcare worker as the primary influence to vaccinate. Wives were more likely to cite their spouse as the primary influence to vaccinate. Families that rejected vaccines were more likely to state their bishop was the most influential person on vaccination.

CONCLUSION

The Holmes County Amish have decreasing vaccine acceptance. Efforts to improve vaccination will require a targeted focus on the primary influences and beliefs of sub-populations within the Amish. Physician advocacy, peer mentorship, father-directed education, and close partnership with Church leadership will be needed to limit vaccine-preventable disease. The Amish may be at risk for low uptake of a COVID-19 vaccine.

Homozygosity for a mutation affecting the catalytic domain of tyrosyl-tRNA synthetase (YARS) causes multisystem disease

Aminoacyl-tRNA synthetases (ARSs) are critical for protein translation. Pathogenic variants of ARSs have been previously associated with peripheral neuropathy and multisystem disease in heterozygotes and homozygotes, respectively. We report seven related children homozygous for a novel mutation in tyrosyl-tRNA synthetase (YARS, c.499C > A, p.Pro167Thr) identified by whole exome sequencing. This variant lies within a highly conserved interface required for protein homodimerization, an essential step in YARS catalytic function. Affected children expressed a more severe phenotype than previously reported, including poor growth, developmental delay, brain dysmyelination, sensorineural hearing loss, nystagmus, progressive cholestatic liver disease, pancreatic insufficiency, hypoglycemia, anemia, intermittent proteinuria, recurrent bloodstream infections and chronic pulmonary disease. Related adults heterozygous for YARS p.Pro167Thr showed no evidence of peripheral neuropathy on electromyography, in contrast to previous reports for other YARS variants. Analysis of YARS p.Pro167Thr in yeast complementation assays revealed a loss-of-function, hypomorphic allele that significantly impaired growth. Recombinant YARS p.Pro167Thr demonstrated normal subcellular localization, but greatly diminished ability to homodimerize in human embryonic kidney cells. This work adds to a rapidly growing body of research emphasizing the importance of ARSs in multisystem disease and significantly expands the allelic and clinical heterogeneity of YARS-associated human disease. A deeper understanding of the role of YARS in human disease may inspire innovative therapies and improve care of affected patients.

Recessive GM3 synthase deficiency: Natural history, biochemistry, and therapeutic frontier

GM3 synthase, encoded by ST3GAL5, initiates synthesis of all downstream cerebral gangliosides. Here, we present biochemical, functional, and natural history data from 50 individuals homozygous for a pathogenic ST3GAL5 c.862C>T founder allele (median age 8.1, range 0.7-30.5 years). GM3 and its derivatives were undetectable in plasma. Weight and head circumference were normal at birth and mean Apgar scores were 7.7 ± 2.0 (1 min) and 8.9 ± 0.5 (5 min). Somatic growth failure, progressive microcephaly, global developmental delay, visual inattentiveness, and dyskinetic movements developed within a few months of life. Infantile-onset epileptic encephalopathy was characterized by a slow, disorganized, high-voltage background, poor state transitions, absent posterior rhythm, and spike trains from multiple independent cortical foci; >90% of electrographic seizures were clinically silent. Hearing loss affected cochlea and central auditory pathways and 76% of children tested failed the newborn hearing screen. Development stagnated early in life; only 13 (26%) patients sat independently (median age 30 months), three (6%) learned to crawl, and none achieved reciprocal communication. Incessant irritability, often accompanied by insomnia, began during infancy and contributed to high parental stress. Despite catastrophic neurological dysfunction, neuroimaging showed only subtle or no destructive changes into late childhood and hospitalizations were surprisingly rare (0.2 per patient per year). Median survival was 23.5 years. Our observations corroborate findings from transgenic mice which indicate that gangliosides might have a limited role in embryonic neurodevelopment but become vital for postnatal brain growth and function. These results have critical implications for the design and implementation of ganglioside restitution therapies.

Underimmunization in Ohio's Amish: parental fears are a greater obstacle than access to care

OBJECTIVE

Holmes County, Ohio, one of the largest Amish communities in the world, has persistently low immunization rates. Studies of other Amish communities have revealed that parents do not immunize their children because of lack of access to immunizations. Our study explored reasons that Amish parents in the previously uninvestigated Holmes County population exempt themselves from immunizations.

METHODS

In January 2007, questionnaires for assessing attitudes regarding immunizations were mailed to a random sampling of 1000 Amish parents in Holmes County.

RESULTS

Thirty-seven percent of the parents responded. Among the 359 respondents, 68% stated that all of their children had received at least 1 immunization, and 17% reported that some of their children had received at least 1 immunization. Only 14% of the parents reported that none of their children had received immunizations. Eighty-six percent of the parents who completely exempted their children from vaccines stated that the main reason they do not vaccinate their children is concern over adverse effects. Many parents indicated that they allow their children to receive only some vaccines because of concern about the way certain vaccines are produced.

CONCLUSIONS

The reasons that Amish parents resist immunizations mirror reasons that non-Amish parents resist immunizations. Even in America's closed religious communities, the major barrier to vaccination is concern over adverse effects of vaccinations. If 85% of Amish parents surveyed accept some immunizations, they are a dynamic group that may be influenced to accept preventative care. Underimmunization in the Amish population must be approached with emphasis on changing parental perceptions of vaccines in addition to ensuring access to vaccines.