A RARE CASE OF HARLEQUIN ICHTHYOSIS SUCCESSFULLY TREATED WITH ACITRETIN: A CASE REPORT AND LITERATURE REVIEW

Harlequin Ichthyosis is the most serious congenital keratinization disorder. When the children are born, they are enveloped in thick horn armor. They are thick yellow horn plates that tear deeply when they dry out. In the most severe form, the children often die in the first few weeks of life. But there are also many milder courses, whereby there are obviously flowing transitions from collodion baby to harlequin ichthyosis. The skin condition later corresponds to that of a child with severe congenital ichthyosis (ARCI). Similar to the collodion baby, cases of harlequin ichthyosis should initially be cared for in the intensive care unit for newborns and require interdisciplinary therapy. Harlequin ichthyosis is caused by very special mutations in the ABCA12 gene. These mutations also have an impact on survival. If homozygous mutations are present, the prospects are worse than if the parents have heterozygous mutations. Homozygous mutations are often present when the parents are consanguineous.

Genetic pathogenesis, diagnosis, and treatment of short-chain 3-hydroxyacyl-coenzyme A dehydrogenase hyperinsulinism

Congenital hyperinsulinism (CHI), a major cause of persistent and recurrent hypoglycemia in infancy and childhood. Numerous pathogenic genes have been associated with 14 known genetic subtypes of CHI. Adenosine triphosphate-sensitive potassium channel hyperinsulinism (KATP-HI) is the most common and most severe subtype, accounting for 40–50% of CHI cases. Short-chain 3-hydroxyacyl-coenzyme A dehydrogenase hyperinsulinism (SCHAD-HI) is a rare subtype that accounts for less than 1% of all CHI cases that are caused by homozygous mutations in the hydroxyacyl-coenzyme A dehydrogenase (HADH) gene. This review provided a systematic description of the genetic pathogenesis and current progress in the diagnosis and treatment of SCHAD-HI to improve our understanding of this disease.

Progranulin deficiency results in reduced bis(monoacylglycero)phosphate (BMP) levels and gangliosidosis

Homozygous mutations of granulin precursor (GRN) lead to neuronal ceroid lipofuscinosis, a severe neurodevelopmental disease, in humans and neuroinflammation in mice. Haploinsufficiency of GRN almost invariably causes frontotemporal dementia (FTD). The GRN locus produces progranulin (PGRN), a lysosomal precursor protein that is cleaved to granulin peptides. Despite intensive investigation, the function of granulins and the reason why their absence causes neurodegeneration remain unclear. Here, we investigated PGRN function in lipid degradation, a major function of lysosomes. We show that PGRN knockout human cells, PGRN-deficient murine brain, and frontal lobes of human brains from subjects with PGRN deficient FTD have increased levels of gangliosides, highly abundant sialic acid containing glycosphingolipids (GSL) that are degraded in lysosomes. Probing how PGRN deficiency causes these changes, we found normal levels and activities of enzymes that catabolize gangliosides. However, levels of bis(monoacylglycero)phosphate (BMP), a lysosomal lipid required for ganglioside catabolism, were markedly reduced in PGRN deficient cells and brain tissues. These data indicate that granulins are required to maintain BMP levels, which regulate ganglioside catabolism, and that PGRN deficiency in lysosomes leads to gangliosidosis. This aberrant accumulation of gangliosides may contribute to neuroinflammation and neurodegeneration susceptibility.

A single-amino-acid in-frame deletion in CYP17A1 results in combined 17-hydroxylase and 17,20-lyase deficiency in an Iranian family despite the protein mutation site

In this study, we detected homozygous mutations in the CYP17A1 gene (NM_000102.4:c.1053_1055delCCT; p.Leu353del; SCV001479329) in a 28-year-old female patient (46,XX) and her phenotypically female 30-year-old sister (46,XY) who had phenotypes consistent with combined 17-hydroxylase and 17,20-lyase deficiency. The phenotypes were not expected based on the location of the mutation in the CYP17A1 redox partner-binding site and a previous description of the same mutation linked with isolated 17,20-lyase deficiency.

Novel homozygous mutations in Pakistani families with Charcot–Marie–Tooth disease

Background Charcot–Marie–Tooth disease (CMT) is a group of genetically and clinically heterogeneous peripheral nervous system disorders. Few studies have identified genetic causes of CMT in the Pakistani patients. Methods This study was performed to identify pathogenic mutations in five consanguineous Pakistani CMT families negative for PMP22 duplication. Genomic screening was performed by application of whole exome sequencing. Results We identified five pathogenic or likely pathogenic homozygous mutations in four genes: c.2599C > T (p.Gln867*) and c.3650G > A (p.Gly1217Asp) in SH3TC2, c.19C > T (p.Arg7*) in HK1, c.247delG (p.Gly83Alafs*44) in REEP1, and c.334G > A (p.Val112Met) in MFN2. These mutations have not been reported in CMT patients. Mutations in SH3TC2, HK1, REEP1, and MFN2 have been reported to be associated with CMT4C, CMT4G, dHMN5B (DSMA5B), and CMT2A, respectively. The genotype–phenotype correlations were confirmed in all the examined families. We also confirmed that both alleles from the homozygous variants originated from a single ancestor using homozygosity mapping. Conclusions This study found five novel mutations as the underlying causes of CMT. Pathogenic mutations in SH3TC2, HK1, and REEP1 have been reported rarely in other populations, suggesting ethnic-specific distribution. This study would be useful for the exact molecular diagnosis and treatment of CMT in Pakistani patients.

Overdominant mutations restrict adaptive loss of heterozygosity at linked loci

Loss of heterozygosity is a common mode of adaptation in asexual diploid populations. Because mitotic recombination frequently extends the full length of a chromosome arm, the selective benefit of loss of heterozygosity may be constrained by linked heterozygous mutations. In a previous laboratory evolution experiment with diploid yeast, we frequently observed homozygous mutations in the WHI2 gene on the right arm of Chromosome XV. However, when heterozygous mutations arose in the STE4 gene, another common target on Chromosome XV, loss of heterozygosity at WHI2 was not observed. Here we show that mutations at WHI2 are partially dominant and that mutations at STE4 are overdominant. We test whether beneficial heterozygous mutations at these two loci interfere with one another by measuring loss of heterozygosity at WHI2 over 1,000 generations for ~300 populations that differed initially only at STE4 and WHI2. We show that the presence of an overdominant mutation in STE4 reduces, but does not eliminate, loss of heterozygosity at WHI2. By sequencing 40 evolved clones, we show that populations with linked overdominant and partially dominant mutations show less parallelism at the gene level, more varied evolutionary outcomes, and increased rates of aneuploidy. Our results show that the degree of dominance and the phasing of heterozygous beneficial mutations can constrain loss of heterozygosity along a chromosome arm, and that conflicts between partially dominant and overdominant mutations can affect evolutionary outcomes.

Orphanic hereditary hypophosphatemic rachit with hypercalciuria, nephrocalcinosis on account of mutation gene SLC34A3(Review and case report)

Orphan Hereditary Hypophosphatemic Rickets with Hypercalciuria (HHRH) (OMIM: 241530; ORPHA: 157215) with an autosomal recessive mode of inheritance occurs with an estimated prevalence of 1: 250,000 in the child population. HHRH was first described by M. Tieder, et al. (1985). The syndrome is caused by heterozygous or homozygous mutations in the SLC34A3 gene mapped to chromosome 9q34.3, which encodes a type II sodium phosphate cotransporter (NaPiIIc). Mutations result in loss of NaPi-IIc function and impairment of phosphate reabsorption in the proximal renal nephron. HHRH is characterized by a decrease in phosphate reabsorption in the proximal nephron tubules, manifested by hyperphosphaturia, hypercalciuria, hypophosphatemia, an increase in the concentration of 1,25(OH) 2D3, a decrease in parathyroid hormone (PTH) circulating in the blood, osteomalacia, inhibition of growth, low corrosiveness, low corrosiveness. The article presents the characteristics of the phenotype and genotype of HHRH, diagnostic criteria and treatment strategy. A description of a clinical case of HHRH with hypercalciuria, nephrocalcinosis and urolithiasis due to mutation of the SLC34A3gene is presented.