The past, present, and future of child growth monitoring: A review and primer for clinical genetics

Child growth measurements are critical vital signs to track, with every individual child growth curve potentially revealing a story about a child's health and well-being. Simply put, every baby born requires basic building blocks to grow and thrive: proper nutrition, love and care, and medical health. To ensure that every child who is missing one of these vital aspects is identified, growth is traditionally measured at birth and each well-child visit. While the blue and pink growth curves appear omnipresent in pediatric clinics, it is surprising to realize that their use only became standard of care in 1977 when the National Center for Health Statistics (NCHS) adopted the growth curve as a clinical tool for health. Behind this practice lies a socioeconomically, culturally, and politically complex interplay of individuals and institutions around the world. In this review, we highlight the often forgotten past, current state of practice, and future potential of this powerful clinical tool: the growth reference chart, with a particular focus on clinical genetics practice. The goal of this article is to understand ongoing work in the field of anthropometry (the scientific study of human measurements) and its direct impact on modern pediatric and genetic patient care.

Metabolic Contributions to Pathobiology of Asthma

Asthma is a heterogenous disorder driven by inflammatory mechanisms that result in multiple phenotypes. Given the complex nature of this condition, metabolomics is being used to delineate the pathobiology of asthma. Metabolomics is the study of metabolites in biology, which includes biofluids, cells, and tissues. These metabolites have a vital role in a disease as they contribute to the pathogenesis of said condition. This review describes how macrometabolic and micrometabolic studies pertaining to these metabolites have contributed to our current understanding of asthma, as well as its many phenotypes. One of the main phenotypes this review will discuss in further detail is obesity as well as diabetes. Distinct roles of metabolites in endotyping asthma and their translation to potential therapy development for asthma is also discussed in this review.

The natural history of type 2 Gaucher disease in the 21st century: A retrospective study

OBJECTIVE

To gather natural history data to better understand the changing course of type 2 Gaucher disease (GD2) in order to guide future interventional protocols.

METHODS

A structured interview was conducted with parents of living or deceased patients with GD2. Retrospective information obtained included disease presentation, progression, medical and surgical history, medications, family history, management, complications, and cause of death, as well as the impact of disease on families.

RESULTS

Data from 23 patients were analyzed (20 deceased and 3 living), showing a mean age at death of 19.2 months, ranging from 3 to 55 months. Fourteen patients were treated with enzyme replacement therapy, 2 were treated with substrate reduction therapy, and 3 underwent bone marrow transplantation. Five patients received ambroxol and one was on N-acetylcysteine, both considered experimental treatments. Fifteen patients had gastrostomy tubes placed; 10 underwent tracheostomies. Neurologic disease manifestations included choking episodes, myoclonic jerks, autonomic dysfunction, apnea, seizures, and diminished blinking, all of which worsened as disease progressed.

CONCLUSIONS

Current available therapies appear to prolong life but do not alter neurologic manifestations. Despite aggressive therapeutic interventions, GD2 remains a progressive disorder with a devastating prognosis that may benefit from new treatment approaches.

Variation in cognitive function over time in Gaucher disease type 3

OBJECTIVE

To identify relevant efficacy parameters essential in designing clinical trials for brain-penetrant therapies for Gaucher disease, we evaluated cognitive function longitudinally in 34 patients with Gaucher disease type 3 seen at the NIH Clinical Center.

METHODS

Individuals were tested with age-appropriate Wechsler Intelligence Scales administered between 1 and 18 times over 29 years. Variation in all IQ domains was not linear with time and was best characterized with the coefficient of variation (SD/mean) for each individual. Mixed-effects regressions were used to determine whether IQ was associated with clinical features. Models were controlled for variation in test version, participant identification, and test administrator.

RESULTS

Mean verbal, performance, and full-scale IQs were 81.77, 75.98, and 82.02, respectively, with a consistent discrepancy between verbal and performance IQs. Mean (SD) verbal, performance, and full-scale coefficient of variations were 0.07 (0.04), 0.09 (0.05), and 0.06 (0.02), respectively. IQ varied about a mean, with no clear trajectory, indicating no clear patterns of improvement or decline over time. EEG lateralization and behavioral issues were consistently associated with IQ.

CONCLUSIONS

The observed variation in IQ in Gaucher disease type 3 across the cohort and within single individuals over time may be characteristic of other neuronopathic diseases. Therefore, to reliably use IQ as an efficacy measure in any clinical trial of neurotherapeutics, a normal variation range must be established to assess the clinical relevance of any IQ change.

Five-parameter evaluation of dysphagia: A novel prognostic scale for assessing neurological decline in Gaucher disease type 2

BACKGROUND

Gaucher disease type 2 (GD2) is defined by acute neurological decline, failure to thrive, and early demise. Currently, there is no clear standard for evaluating, staging, and counseling regarding neurological decline in GD2. Due to the high prevalence of progressive dysphagia secondary to acute neurological involvement, we aimed to identify key components of swallow function which could serve as markers of disease progression in GD2.

METHODS

A post-hoc analysis of modified barium swallow studies was performed. Six parameters of swallowing were scored in a retrospective chart review of eleven infants with GD2. Mixed effects regression, principal component analysis (PCA), and a transition analysis were used to evaluate swallow function and model disease progression.

RESULTS

All patients exhibited impaired swallow function. There was no association between any of the swallow parameters and age, indicating non-linear disease progression. PCA and transition analysis identified five parameters capturing multiple dimensions of swallowing which defined two distinct disease states.

CONCLUSION

A five-parameter swallow evaluation was sufficient to identify distinct states of GD2 and model prospective outcomes. This multi-dimensional evaluation could be a useful efficacy parameter for future therapeutic trials in GD2 and other neurodegenerative disorders of infancy.

Induced pluripotent stem cell models of lysosomal storage disorders

Induced pluripotent stem cells (iPSCs) have provided new opportunities to explore the cell biology and pathophysiology of human diseases, and the lysosomal storage disorder research community has been quick to adopt this technology. Patient-derived iPSC models have been generated for a number of lysosomal storage disorders, including Gaucher disease, Pompe disease, Fabry disease, metachromatic leukodystrophy, the neuronal ceroid lipofuscinoses, Niemann-Pick types A and C1, and several of the mucopolysaccharidoses. Here, we review the strategies employed for reprogramming and differentiation, as well as insights into disease etiology gleaned from the currently available models. Examples are provided to illustrate how iPSC-derived models can be employed to develop new therapeutic strategies for these disorders. We also discuss how models of these rare diseases could contribute to an enhanced understanding of more common neurodegenerative disorders such as Parkinson’s disease, and discuss key challenges and opportunities in this area of research.

Summary: This Review discusses how induced pluripotent stem cells (iPSCs) provide new opportunities to explore the biology and pathophysiology of lysosomal storage diseases, and how iPSCs have illuminated the role of lysosomes in more common disorders.

Type 2 Gaucher disease in an infant despite a normal maternal glucocerebrosidase gene

Gaucher disease (GD) is a recessively inherited autosomal lysosomal storage disease, the most severe of which is type 2, an acute neuronopathic form. We report an affected infant who inherited one mutant allele, Arg257Gln (c.887G>A; p.Arg296Gln) from his father, while the second, Gly202Arg (c.721G>A; p.Gly241Arg) arose by either maternal germline mosaicism or as a de novo mutation. This is the first time mutation Gly202Arg has been reported to be inherited non-traditionally. This report is part of a growing literature suggesting that GD can be inherited via germline or de novo mutations, and emphasizes that it is critical for clinicians to consider such inheritance when making diagnostic decisions or providing genetic counseling.

The Spectrum of Neurological Manifestations Associated with Gaucher Disease

Gaucher disease, the most common lysosomal storage disorder, is due to a deficiency in the enzyme glucocerebrosidase. This leads to the accumulation of its normal substrate, glucocerebroside, in tissue macrophages, affecting the hematological, visceral, bone and neurologic systems. Gaucher disease is classified into three broad phenotypes based upon the presence or absence of neurological involvement: type 1 (non-neuronopathic), type 2 (acute neuronopathic), and type 3 (subacute neuronopathic). Phenotypically, there is a wide spectrum of visceral and neurological manifestations. Enzyme replacement is effective in managing the visceral disease; however, treating the neurological manifestations has proved to be more challenging. This review discusses the various neurological manifestations encountered in Gaucher disease, and provides a brief overview regarding the treatment and ongoing research challenges.

Dopa responsive dystonia with diurnal fluctuation (Segawa's syndrome)

A 10-year-old girl presented with progressive dystonia with diurnal fluctuation. Response to low dose L-Dopa was dramatic and sustained with no complications. Recurrence of symptoms was observed on attempted withdrawal. Because of the dramatic response to therapy, dopa-responsive dystonia must be considered in the differential diagnosis of disorders presenting as gait disorders in childhood.