Hypochondroplasia, Acanthosis Nigricans, and Insulin Resistance in a Child with FGFR3 Mutation: Is It Just an Association?

FGFR3 mutations cause wide spectrum of disorders ranging from skeletal dysplasias (hypochondroplasia, achondroplasia, and thanatophoric dysplasia), benign skin tumors (epidermal nevi, seborrhaeic keratosis, and acanthosis nigricans), and epithelial malignancies (multiple myeloma and prostate and bladder carcinoma). Hypochondroplasia is the most common type of short-limb dwarfism in children resulting from fibroblast growth factor receptor 3 (FGFR3) mutation. Acanthosis nigricans might be seen in severe skeletal dysplasia, including thanatophoric dysplasia and SADDAN syndrome, without a biochemical evidence of hyperinsulinemia. Insulin insensitivity and acanthosis nigricans are uncommonly seen in hypochondroplasia patients with FGFR3 mutations which may represent a new association. We aim to describe the association of hypochondroplasia, acanthosis nigricans, and insulin resistance in a child harboring FGFR3 mutation. To our knowledge, this is the first case report associating the p.N540 with acanthosis nigricans and the second to describe hyperinsulinemia in hypochondroplasia. This finding demonstrates the possible coexistence of insulin insensitivity and acanthosis nigricans in hypochondroplasia patients

Case Report Hypochondroplasia, Acanthosis Nigricans, and Insulin Resistance in a Child with FGFR3 Mutation: Is It Just an Association?

FGFR3 mutations cause wide spectrum of disorders ranging from skeletal dysplasias (hypochondroplasia, achondroplasia, and thanatophoric dysplasia), benign skin tumors (epidermal nevi, seborrhaeic keratosis, and acanthosis nigricans), and epithelial malignancies (multiple myeloma and prostate and bladder carcinoma). Hypochondroplasia is the most common type of shortlimb dwarfism in children resulting from fibroblast growth factor receptor 3 (FGFR3) mutation. Acanthosis nigricans might be seen in severe skeletal dysplasia, including thanatophoric dysplasia and SADDAN syndrome, without a biochemical evidence of hyperinsulinemia. Insulin insensitivity and acanthosis nigricans are uncommonly seen in hypochondroplasia patients with FGFR3 mutations which may represent a new association. We aim to describe the association of hypochondroplasia, acanthosis nigricans, and insulin resistance in a child harboring FGFR3 mutation. To our knowledge, this is the first case report associating the p.N540 with acanthosis nigricans and the second to describe hyperinsulinemia in hypochondroplasia. This finding demonstrates the possible coexistence of insulin insensitivity and acanthosis nigricans in hypochondroplasia patients

Double homozygous Cystic Fibrosis Transmembrane Regulator gene (CFTR) mutation: A case series and review of the literature

Introduction: Double homozygous mutation with the presence of double mutations in each allele is a very rare phenomenon with only 2 reports that have described this phenomenon in the medical literature.Objective: To find the prevalence of double homozygous in our Cf population and to describe their mutations and review of the literature in this phenomenon.Methodology: A case series and a review of the literature from 1989-2020 for similar phenomenon.Results: A total of 396 patients (312 families) confirmed CF that were positive for the cystic fibrosis transmembrane conductance regulator (CFTR) variants from January 1998 to December 2018. A total of four families that constitute 4 patients were positive for double homozygous CFTR mutations in Trans position status. All parents were first-degree cousins. Their clinical pictures were of the severe type in relation to chest disease and failure to thrive. Family screening showed that 7 family members were carriers with double heterozygous mutations in Cis position. The Prevalence of double homozygous CFTR mutation in our study is 4/312 families or 1-2:100 families which is the highest that has been reported in the medical literature. Literature review showed only 2 cases of double homozygous were reported in 1995 and 2017.&nbsp;Conclusion: Double homozygous CFTR mutations are common in the Saudi population due to consanguinity. Proper and extended genetic counseling is needed for the same family and their relatives to prevent similar conditions.</p

The first case report of double homozygous of 2 different mutations in the CFTR gene in Saudi Arabia

The first cases of a rare double homozygosity of two different mutations in the cystic fibrosis trans-regulator gene (CFTR) of a cystic fibrosis patient in Saudi Arabia. Details of the family screening and a review of the literature on similar cases are discussed

Spectrum of mutations underlying Propionic acidemia and further insight into a genotype-phenotype correlation for the common mutation in Saudi Arabia

Propionic acidemia (PA) is an autosomal recessive metabolic disorder. PA is characterized by deficiency of the mitochondrial enzyme propionyl CoA carboxylase (PCC) that results in the accumulation of propionic acid. Alpha and beta subunits of the PCC enzyme are encoded by the PCCA and PCCB genes, respectively. Pathogenic variants in PCCA or PCCB disrupt the function of the PCC enzyme preventing the proper breakdown of certain amino acids and metabolites. To determine the frequency of pathogenic variants in PA in our population, 84 Saudi Arabian patients affected with PA were sequenced for both the PCCA and PCCB genes. We found that variants in PCCA accounted for 81% of our cohort (68 patients), while variants in PCCB only accounted for 19% (16 patients). In total, sixteen different sequence variants were detected in the study, where 7 were found in PCCA and 9 in PCCB. The pathogenic variant (c.425G > A; p.Gly142Asp) in PCCA is the most common cause of PA in our cohort and was found in 59 families (70.2%), followed by the frameshift variant (c.990dupT; p.E331Xfs*1) in PCCB that was found in 7 families (8.3%). The p.Gly142Asp missense variant is likely to be a founder pathogenic variant in patients of Saudi Arabian tribal origin and is associated with a severe phenotype. All variants were inherited in a homozygous state except for one family who was compound heterozygous. A total of 11 novel pathogenic variants were detected in this study thereby increasing the known spectrum of pathogenic variants in the PCCA and PCCB genes. Keywords: Propionic acidemia, PCCA, PCCB, Founder mutation, Genotype-phenotype correlatio