Inherited skin disorders presenting with poikiloderma

Hereditary fibrosing poikiloderma (POIKTMP syndrome) report of a new mutation and review of the literature

Hereditary fibrosing poikiloderma with tendon contractures, myopathy, and pulmonary fibrosis (POIKTMP) is a genodermatosis with autosomal dominant inheritance caused by mutations in FAM111B. We report another case with a new pathogenic variant and analyze all previously published 34 cases with a focus on sequence of clinical presentation and genotype-phenotype correlation. POIKTMP is characterized by marked age-dependent clinical expressivity. FAM111B encodes a catalytic nuclear protein, expressed in many tissues, which contributes to impaired DNA repair affecting multiple systems. Specific inhibition of catalytic activity might be a future strategy to halt progression of this otherwise untreatable disease. Given the relentless progression of the disease, it would make sense to start such treatment as early as possible. In order to achieve this objective, children with suspected POIKTMP should therefore undergo early imaging of all relevant organ systems.

Case Report: Diverse phenotypes of congenital poikiloderma associated with FAM111B mutations in codon 628: A case report and literature review

Congenital poikiloderma is an extremely rare autosomal dominant genetic syndrome, characterized by a combination of early onset poikiloderma, telangiectasia, and epidermal atrophy. FAM111B gene with multiple mutations has been identified as a potential causative gene for congenital poikiloderma. In this report, we described a boy with congenital poikiloderma confirmed by clinical manifestations. Next-generation sequencing based on a gene probe panel consisting of 541 genetic loci of genodermatoses, was used to screen mutations of the proband and his parents. Results showed that a missense mutation in the FAM111B gene c.1883G>A (rs587777238) was identified in the proband, but absent in his parents, indicating the mutation is de novo. In conclusion, a new case of congenital poikiloderma in China was reported, and the hotspot mutations in codon 628 of FAM111B gene was reviewed, as well as authenticating the uncertain association between genotypes and phenotypes in this rare disease.

Mutations in the ribosome biogenesis factor gene LTV1 are linked to LIPHAK syndrome, a novel poikiloderma-like disorder

In the framework of the UK 100 000 Genomes Project, we investigated the genetic origin of a previously undescribed recessive dermatological condition, which we named LIPHAK (LTV1-associated Inflammatory Poikiloderma with Hair abnormalities and Acral Keratoses), in four affected individuals from two UK families of Pakistani and Indian origins, respectively. Our analysis showed that only one gene, LTV1, carried rare biallelic variants that were shared in all affected individuals, and specifically they bore the NM_032860.5:c.503A > G, p.(Asn168Ser) change, found homozygously in all of them. In addition, high-resolution homozygosity mapping revealed the presence of a small 652-kb stretch on chromosome 6, encompassing LTV1, that was haploidentical and common to all affected individuals. The c.503A > G variant was predicted by in silico tools to affect the correct splicing of LTV1's exon 5. Minigene-driven splicing assays in HEK293T cells and in a skin sample from one of the patients confirmed that this variant was indeed responsible for the creation of a new donor splice site, resulting in aberrant splicing and in a premature termination codon in exon 6 of this gene. LTV1 encodes one of the ribosome biogenesis factors that promote the assembly of the small (40S) ribosomal subunit. In yeast, defects in LTV1 alter the export of nascent ribosomal subunits to the cytoplasm; however, the role of this gene in human pathology is unknown to date. Our data suggest that LIPHAK could be a previously unrecognized ribosomopathy.