Mutation in ALOX12B likely cause of POI and also ichthyosis in a large Iranian pedigree

The landscape of genetic variations in non-syndromic primary ovarian insufficiency in the MENA region: a systematic review

Introduction

Premature ovarian insufficiency (POI) is a primary cause of infertility with variable clinical manifestations. POI is a multifactorial disease with both environmental and known genetic etiologies, but data on the genetic variations associated with POI in the Middle East and North Africa (MENA) region are scarce. The aim of this study was to systematically review all known genetic causes of POI in the MENA region.

Methods

The PubMed, Science Direct, ProQuest, and Embase databases were searched from inception to December 2022 for all reports of genetic variants associated with POI in the MENA region. Clinical and genetic data were collected from eligible articles, and ClinVar and PubMed (dbSNP) were searched for variants.

Results

Of 1,803 studies, 25 met the inclusion criteria. Fifteen studies were case-control studies and ten were case reports representing 1,080 non-syndromic POI patients in total. Seventy-nine variants in 25 genes associated with POI were reported in ten MENA countries. Of the 79 variants, 46 were rare and 33 were common variants. Of the 46 rare variants, 19 were pathogenic or likely pathogenic according to ACMG classification guidelines and ClinVar. No clear phenotype-genotype association was observed. Male family members carrying pathogenic variants also had infertility problems.

Discussion

To our best knowledge, this is the first systematic review of the genetic variants associated with POI in the MENA region. Further functional studies are needed to assess the disease-causing molecular mechanisms of these variants. Knowledge of the genetic basis of POI in the Middle East could facilitate early detection of the condition and thus early implementation of therapeutic interventions, paving the way for precision medicine options in specific populations.

Identification of the first congenital ichthyosis case caused by a homozygous deletion in the ALOX12B gene due to chromosome 17 mixed uniparental disomy

Uniparental disomy (UPD) is a rare genetic event caused by errors during gametogenesis and fertilization leading to two copies of a chromosome or chromosomal region inherited from one parent. MixUPD is one type of UPD that contains isodisomic and heterodisomic parts because of meiotic recombination. Using whole-exome sequencing (WES), we identified the first case of ichthyosis due to a maternal mixUPD on chromosome 17, which results in a homozygous deletion of partial intron 8 to exon 10 in ALOX12B, being predicted to lead to an internal protein deletion of 97 amino acids. We also performed a retrospective analysis of 198 patients with ALOX12B mutations. The results suggested that the exon 9 and 10 are located in the mutational hotspots of ALOX12B. In addition, our patient has microtia and congenital stenosis of the external auditory canals, which is very rare in patients with ALOX12B mutations. Our study reports the first case of autosomal recessive congenital ichthyosis (ARCI) due to a mixUPD of chromosome 17 and expands the spectrum of clinical manifestations of ARCI caused by mutations in the ALOX12B gene.