Diagnostic yield of genetic testing in 324 infants with hypotonia

Whole genome sequencing diagnostic yield for paediatric patients with suspected genetic disorders: systematic review, meta-analysis, and GRADE assessment

BACKGROUND

About 80% of the roughly 7,000 known rare diseases are single gene disorders, about 85% of which are ultra-rare, affecting less than one in one million individuals. NGS technologies, in particular whole genome sequencing (WGS) in paediatric patients suffering from severe disorders of likely genetic origin improve the diagnostic yield allowing targeted, effective care and management. The aim of this study is to perform a systematic review and meta-analysis to assess the effectiveness of WGS, with respect to whole exome sequencing (WES) and/or usual care, for the diagnosis of suspected genetic disorders among the paediatric population.

METHODS

A systematic review of the literature was conducted querying relevant electronic databases, including MEDLINE, EMBASE, ISI Web of Science, and Scopus from January 2010 to June 2022. A random-effect meta-analysis was run to inspect the diagnostic yield of different techniques. A network meta-analysis was also performed to directly assess the comparison between WGS and WES.

RESULTS

Of the 4,927 initially retrieved articles, thirty-nine met the inclusion criteria. Overall results highlighted a significantly higher pooled diagnostic yield for WGS, 38.6% (95% CI: [32.6 - 45.0]), in respect to WES, 37.8% (95% CI: [32.9 - 42.9]) and usual care, 7.8% (95% CI: [4.4 - 13.2]). The meta-regression output suggested a higher diagnostic yield of the WGS compared to WES after controlling for the type of disease (monogenic vs non-monogenic), with a tendency to better diagnostic performances for Mendelian diseases. The network meta-analysis showed a higher diagnostic yield for WGS compared to WES (OR = 1.54, 95%CI: [1.11 - 2.12]).

CONCLUSIONS

Although whole genome sequencing for the paediatric population with suspected genetic disorders provided an accurate and early genetic diagnosis in a high proportion of cases, further research is needed for evaluating costs, effectiveness, and cost-effectiveness of WGS and achieving an informed decision-making process.

TRIAL REGISTRATION

This systematic review has not been registered.

Assessing floppy infants: a new module

Our aim was to develop a new module for assessing the floppy infant, to describe the application of the module in a cohort of low-risk newborns and piloting the module in a cohort of floppy infants. The module was applied to a cohort of 143 low-risk newborns and piloted in in a cohort of 24 floppy infants. The new add-on module includes a neurological section and provides a section for recording information obtained by physical examination and antenatal history. For each item, column 1 reports abnormal findings, column 3 normal findings, and column 2 intermediate signs to be followed. Consistent with previous studies, in low-risk infants, none had definitely abnormal or mildly abnormal signs, with the exception of tendon reflexes that were not easily elicitable in 17.14% of term-born infants.

CONCLUSION

Our study suggest that the module can be easily used in a clinical setting as an add-on to the regular neonatal neurological examination in newborns identified as hypotonic on routine examination. Larger cohorts are needed to establish the accuracy of the prognostic value of the module in the differential diagnosis of floppy infant.

WHAT IS KNOWN

• Hypotonia is one of the key signs in newborns with neuromuscular disorders and can be associated with a wide range of other conditions (central nervous system involvement, genetic and metabolic diseases). • Weakness or/and contractures can identify infants with a neuromuscular disorder and help in the differential diagnosis of floppy infants.

WHAT IS NEW

• To date, this is the first attempt to develop and apply a specific neurological module for the assessment of the floppy infant. • The module can be used in a routine clinical setting as an add-on to the regular neurological examination and has potential to differentiate the floppy infants from the low-risk infants.