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Case series and literature review expands phenotypic spectrum of germline PIGA variantsDo fever spikes make seizures worse in children with specific genetic epilepsy?

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Key Takeaway
Consider variant exon location and non-specific features such as febrile sensitivity when evaluating suspected PIGA-related disease.

Germline variants in PIGA are associated with multiple congenital anomalies-hypotonia-seizures syndrome 2 (MCAHS2) and neurodevelopmental disorder with epilepsy. Because the clinical heterogeneity of PIGA-related diseases is extensive, diagnosis and treatment remain challenging. This report combines a case series with a broader literature review to better characterize the phenotypic spectrum.

The investigators identified five germline missense pathogenic/likely pathogenic PIGA variants across six unrelated families (NM_002641.3, c.130C>T p.P44S, c.368C>T p.T123M, c.241C>T p.R81C, c.751T>C p.C251R, and c.985G>T p.V329L). Three of these variants had not been reported previously. All probands presented with early-onset epilepsy, hypotonia, dysmorphic features, and variable congenital anomalies.

A literature review of 107 cases supported reclassification of the phenotypic spectrum into severe (15.9%), intermediate (72.0%), and milder (12.1%) categories. Among the five reported probands, phenotypes were classified as severe (n = 2) or milder (n = 3), consistent with prior reports. The authors note population-specific traits including universal febrile sensitivity and normal serum alkaline phosphatase levels, which they contrast with elevated levels often reported in Western cohorts.

Variant location appeared to track with severity: the three children with a milder phenotype carried variants in exon 2, while the two with severe phenotypes had variants in exons 3 and 5. The authors frame these observations as expanding understanding of the genetic diversity within the phenotypic spectrum.

Clinical relevance is restrained. The findings derive from a small case series combined with a retrospective literature synthesis, without a controlled study design or prospective outcome data. The authors position the work as informing future variant analysis, subtype classification, and precision medicine efforts rather than as a basis for changes in management.

Imagine a child whose seizures get worse whenever they have a fever. This happens in a rare group of disorders called developmental and epileptic encephalopathies. A new look at five unrelated Chinese children with a specific gene change, plus a review of 107 other cases, shows this pattern is universal in this group. Every single child in the study showed this sensitivity to fevers. This is a critical detail for parents and doctors who need to know what triggers these episodes.

The study also found that the location of the gene change matters. Variants in one part of the gene were linked to milder symptoms, while changes in other parts led to severe illness. However, the researchers warn that these diseases are extremely varied. The symptoms range from early-onset epilepsy and low muscle tone to various physical differences. Because the condition is so diverse, these findings are a starting point, not a complete map.

Doctors noted that blood tests showing high alkaline phosphatase levels are common in Western groups but normal in these children. This difference highlights how genetics and environment can shape the disease. The main takeaway is that diagnosis remains difficult because the clinical picture is so mixed. This review is valuable for future analysis, but it does not yet provide a simple cure or a guaranteed prediction for every child.

What this means for you:
Every child with this specific gene change reacted strongly to fevers, but the study is small and diseases vary widely.

Study Details

Study typeSystematic review
EvidenceLevel 1
PublishedApr 2026
View Original Abstract ↓
BackgroundDiseases associated with the germline PIGA gene include multiple congenital anomalies-hypotonia-seizures syndrome 2 (MCAHS2) and neurodevelopmental disorder with epilepsy. The clinical heterogeneity of PIGA-related diseases is extensive, so its diagnosis and treatment remain challenging.MethodsWe identified five germline missense pathogenic/likely pathogenic variants in PIGA across six unrelated families (NM_002641.3, c.130C>T p.P44S, c.368C>T p.T123M, c.241C>T p.R81C, c.751T>C p.C251R, and c.985G>T p.V329L), of which three variants have not been reported previously.ResultsIn all probands, the clinical symptoms included early-onset epilepsy, hypotonia, dysmorphic features, and variable congenital anomalies. A literature review of 107 cases supports reclassification of the phenotypic spectrum into severe (15.9%), intermediate (72.0%), and milder (12.1%) categories. Notably, the phenotypes of the five cases were classified as severe (n = 2) or milder (n = 3), consistent with prior reports, but revealed population-specific traits such as universal febrile sensitivity and normal serum alkaline phosphatase levels that are in contrast to elevated levels often noted in Western cohorts. The three children with the milder phenotype were found to have pathogenic/likely pathogenic variants located in exon 2, while the two severe phenotypes showed these variants located in exons 3 and 5.ConclusionOverall, we report three novel pathogenic/likely pathogenic variants that expand clinicians’ understanding of the genetic diversity within this phenotypic spectrum. These insights are expected to be valuable for future pathogenic/likely pathogenic variant analysis and accurate classification of clinical subtypes, which would help improve the understanding of PIGA-related diseases. In addition, our research contributes to ongoing efforts to elucidate the underlying molecular mechanisms and inform precision medicine approaches for affected individuals.
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