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1.  A homozygous splicing mutation in ELAC2 suggests phenotypic variability including intellectual disability with minimal cardiac involvement 
Background
The group of ELAC2-related encephalomyopathies is a recent addition to the rapidly growing heterogeneous mitochondrial disorders.
Results
We describe a highly inbred consanguineous Pakistani family with multiple affected children in 2 branches exhibiting moderately severe global developmental delay. Using homozygosity mapping, we mapped the phenotype in this family to a single locus on chromosome 17. In addition, whole-exome sequencing identified a homozygous splicing mutation (c.1423 + 2 T > A) in ELAC2 gene that disrupted the canonical donor splice site of intron 15 of all known isoforms. A noticeable reduction in ELAC2 expression was observed in patients compared to controls. In addition, patients exhibited significantly increased levels of 5′ end unprocessed mt-RNAs compared to the control fibroblast cells.
Conclusions
The only three previously reported families with defects in ELAC2 gene exhibited infantile hypertrophic cardiomyopathy and complex I deficiency. In contrast, our patients exhibited intellectual disability as the main feature with minimal cardiac involvement. Therefore our findings expand the phenotypic spectrum of ELAC2- associated disorders illustrating clinical heterogeneity of mutations in this gene. In addition, ELAC2 mutations should be considered when evaluating patient with mainly intellectual disability phenotypes.
Electronic supplementary material
The online version of this article (doi:10.1186/s13023-016-0526-8) contains supplementary material, which is available to authorized users.
doi:10.1186/s13023-016-0526-8
PMCID: PMC5073853  PMID: 27769300
ELAC2; Mitochondrial disorder; 5′ end unprocessed mt-RNAs; Splice site mutation; Intellectual disability; Respiratory chain complex I (RCCI) deficiency
2.  LINS, a modulator of the WNT signaling pathway, is involved in human cognition 
Background
Inherited intellectual disability (ID) conditions are a group of genetically heterogeneous disorders that lead to variable degrees of cognition deficits. It has been shown that inherited ID can be caused by mutations in over 100 different genes and there is evidence for the presence of as yet unidentified genes in a significant proportion of patients. We aimed at identifying the defective gene underlying an autosomal recessive ID in two sibs of an Emirati family.
Methods
A combined approach involving homozygosity mapping and whole-exome sequencing was used to identify the causative mutation. RNA analysis was performed to gain further insight into the pathogenic effect of the detected mutation.
Results
We have identified a homozygous splicing mutation (c.1219_1222+1delAAAGG) in the LINS gene in the affected children. LINS is the human homologue of the Drosophila segment polarity gene lin that encodes an essential regulator of the wingless/Wnt signaling. The identified mutation alters the first consensus nucleotide of the 5' donor splice junction of intron 5 and the 3' end of exon 5. Transcript analysis revealed that this change leads to an exon skipping event resulting in direct splicing of exon 4 to exon 6. Another mutation in LINS has been described very briefly in an Iranian family with autosomal recessive ID and microcephaly.
Conclusion
Our study confirms that LINS, a modulator of the WNT pathway, is an indispensable gene to human cognition and this finding sheds further light on the importance of WNT signaling in human brain development and/or function.
doi:10.1186/1750-1172-8-87
PMCID: PMC3847167  PMID: 23773660
3.  A mutation in KIF7 is responsible for the autosomal recessive syndrome of macrocephaly, multiple epiphyseal dysplasia and distinctive facial appearance 
Background
We previously reported the existence of a unique autosomal recessive syndrome consisting of macrocephaly, multiple epiphyseal dysplasia and distinctive facial appearance mapping to chromosome 15q26.
Methods
In this manuscript, we have used whole exome sequencing on two affected members of a consanguineous family with this condition and carried out detailed bioinformatics analysis to elucidate the causative mutation.
Results
Our analysis resulted in the identification of a homozygous p.N1060S missense mutation in a highly conserved residue in KIF7, a regulator of Hedgehog signaling that has been recently found to be causing Joubert syndrome, fetal hydrolethalus and acrocallosal syndromes. The phenotype in our patients partially overlaps with the phenotypes associated with those syndromes but they also exhibit some distinctive features including multiple epiphyseal dysplasia.
Conclusions
We report the first missense homozygous disease-causing mutation in KIF7 and expand the clinical spectrum associated with mutations in this gene to include multiple epiphyseal dysplasia. The missense nature of the mutation might account for the unique presentation in our patients.
doi:10.1186/1750-1172-7-27
PMCID: PMC3492204  PMID: 22587682
KIF7; Acrocallosal; Joubert; Sonic hedgehog; Dysmorphism; Multiple epiphyseal dysplasia; Fetal hydrolethalus

Results 1-3 (3)