A national long-read sequencing study on chromosomal rearrangements uncovers hidden complexities.

Clinical genetic laboratories often require a comprehensive analysis of chromosomal rearrangements/structural variants (SVs), from large events like translocations and inversions to supernumerary ring/marker chromosomes and small deletions or duplications. Understanding the complexity of these events and their clinical consequences requires pinpointing breakpoint junctions and resolving the derivative chromosome structure. This task often surpasses the capabilities of short-read sequencing technologies.

Hyperinsulinemia in Sotos Syndrome with a Deletion.

Sotos syndrome belongs to the group of diseases characterised by features such as facial dysmorphism, intellectual disability, hypotonia and overgrowth. Usually, Sotos syndrome is caused by heterozygous mutations in the NSD1 gene at chromosome 5q35 or by large genomic deletions of the same region. Genotype-phenotype correlations have mainly been reported as an association of significant or major abnormalities and presence of 5q35 deletions rather than intragenic deletions or point mutations in NSD1.

Pre- and postnatal growth failure with microcephaly due to two novel heterozygous IGF1R mutations and response to growth hormone treatment.

Aim: To explore the phenotype and response to growth hormone in patients with heterozygous mutations in the insulin-like growth factor I receptor gene (IGF1R).

Methods: Children with short stature, microcephaly, born SGA combined with biochemical sign of IGF-I insensitivity were analysed for IGF1R mutations or deletions using Sanger sequencing and Multiple ligation-dependent probe amplification analysis.

Results: In two families, a novel heterozygous non-synonymous missense IGF1R variant was identified.

Genomic screening in rare disorders: New mutations and phenotypes, highlighting ALG14 as a novel cause of severe intellectual disability.

We have investigated 20 consanguineous families with multiple children affected by rare disorders. Detailed clinical examinations, exome sequencing of affected as well as unaffected family members and further validation of likely pathogenic variants were performed. In 16/20 families, we identified pathogenic variants in autosomal recessive disease genes (ALMS1, PIGT, FLVCR2, TFG, CYP7B1, ALG14, EXOSC3, MEGF10, ASAH1, WDR62, ASPM, PNPO, ERCC5, KIAA1109, RIPK4, MAN1B1).

Primary immunodeficiency diseases: Genomic approaches delineate heterogeneous Mendelian disorders.

Background: Primary immunodeficiency diseases (PIDDs) are clinically and genetically heterogeneous disorders thus far associated with mutations in more than 300 genes. The clinical phenotypes derived from distinct genotypes can overlap. Genetic etiology can be a prognostic indicator of disease severity and can influence treatment decisions.

Genotype-phenotype correlations in Bothnia dystrophy caused by RLBP1 gene sequence variations.

Purpose: To evaluate phenotypes caused by different RLBP1 mutations in autosomal recessive retinitis pigmentosa of Bothnia type.

Methods: Compound heterozygotes for mutations in the RLBP1 gene [c.677T>A]+[c.