Two novel pathogenic variants in MED13L: one familial and one isolated case.
Two fresh MED13L gene faults now join the list that can cause intellectual disability.
01Research in Context
What this study did
Doctors looked at two children with severe delays. One child had a brand-new MED13L gene change. The other child’s family already carried the same change.
The team wrote down each child’s medical facts. They checked the gene lab work and compared it with past reports.
What they found
Both kids had never-before-seen MED13L faults. These faults add two more “spelling mistakes” to the list that cause intellectual disability.
One fault traveled through the family. The other appeared for the first time in that child.
How this fits with other research
DAdams et al. (2024) did the same job for Bryant-Li-Bhoj syndrome. Both papers simply map new gene changes and describe the kids who have them.
Lotfizadeh et al. (2020) also listed new gene changes, but in MECP2. The method is twin-like: collect rare patients, run gene tests, publish the list.
de Leeuw et al. (2024) looked at 16p11.2 copy-number changes and found clear behavior links. Hamama et al. (2021) stops at naming the gene; it does not yet say which behaviors go with it.
Why it matters
You may meet a child who tests positive for a MED13L variant. This paper gives you two new codes to watch for. Until behavior data arrive, treat the child’s delays as you normally would while staying alert for possible heart or speech issues already tied to MED13L. Share the family-tree finding with parents so they can seek genetic counseling.
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02At a glance
03Original abstract
BACKGROUND: Genetic variants involving the MED13L gene can lead to an autosomal dominant syndrome characterised by intellectual disability/developmental delay and facial dysmorphism. METHODS: We investigated two cases (one familial and one isolated) of intellectual disability with speech delay and dysmorphic facial features by whole-exome sequencing analyses. Further, we performed a literature review about clinical and molecular aspects of MED13L gene and syndrome. RESULTS: Two MED13L variants have been identified [MED13L(NM_015335.5):c.4417C>T and MED13L(NM_015335.5):c.2318delC] and were classified as pathogenic according to the ACMG (American College of Medical Genetics and Genomics) guidelines. One of the variants was present in sibs. CONCLUSIONS: The two pathogenic variants identified have not been previously reported. Importantly, this is the first report of a familial case of MED13L nonsense mutation. Although the parents of the affected children were no longer available for analysis, their apparently normal phenotypes were surmised from familial verbal descriptions corresponding to normal mental behaviour and phenotype. In this situation, the familial component of mutation transmission might be caused by gonadal mosaicism of a MED13L mutation in a gonad from either the father or the mother. The case reports and the literature review presented in this manuscript can be useful for genetic counselling.
Journal of intellectual disability research : JIDR, 2021 · doi:10.1111/jir.12891