A rare variant in the FHL1 gene associated with X-linked recessive hypoparathyroidism.

Isolated familial hypoparathyroidism is an extremely rare disorder, which to date has been linked to several loci including mutations in CASR, GCM2, and PTH, as well as a rare condition defined as X-linked recessive hypoparathyroidism, previously associated with a 1.5 Mb region on Xq26-q27. Here, we report a patient with hypocalcemia-induced seizures leading to the diagnosis of primary hypoparathyroidism. Mutations in CASR, GCM2, and PTH were ruled out, while whole exome sequencing of the family suggested FHL1, located on chromosome Xq26, as the most likely causative gene variant (FHL1, exon 4, c.C283T, p.R95W). Since FHL1 has not been linked to calcium regulation before, we provide evidence for its functional role in hypoparathyroidism by: (i) bioinformatics analysis coupling its action to known modulators of PTH function; (ii) observing strong expression of fhl1b in Corpuscles of Stannius, gland-like aggregates in zebrafish that function in calcium regulation similar to mammalian PTH; and (iii) implicating fhl1b and FHL1 as regulators of calcium homeostasis in zebrafish and human cells, respectively. Altogether, our data suggest that FHL1 is a novel regulator of calcium homeostasis and implicate it as the causative gene for X-linked recessive hypoparathyroidism.

X-linked elliptocytosis with impaired growth is related to mutated AMMECR1.

In this study, we report a family with X-linked recessive syndrome caused by mutated AMMECR1 and characterized by elliptocytosis with or without anemia, midface hypoplasia, proportionate short stature and hearing loss. Recently, mutations in AMMECR1 were reported in two maternal half-brothers, presenting with nephrocalcinosis, midface hypoplasia and, in one of the siblings, deafness and elliptocytosis. AMMECR1 gene is localized in the critical region of contiguous deletion syndrome on Xq22.3 implicated in Alport syndrome, mental retardation, midface hypoplasia, and elliptocytosis (AMME complex). Interestingly, alternative splicing of exon 2, the same exon harboring the truncating mutation, was observed in the proband and in his unaffected mother. Alternative splicing of this exon is predicted to lead to an in-frame deletion. We provide further evidence that mutated AMMECR1 gene is responsible for this clinically recognizable X-linked condition with variable expressivity.

Actionable clinical decisions based on comprehensive genomic evaluation in asymptomatic adults.

Whole-exome sequencing (WES) arises as a new approach in diagnosing individuals affected by multigenic and complex phenotypes. Herein, we aim to examine whether WES is useful in screening asymptomatic individuals for actionable interventions, which has not yet been established. Twenty-five healthy adults underwent WES, bioinformatics, and manual curation of their exomes. Six participants (24%) harbored significant, management-changing variants in cancer predisposition genes, American College of Medical Genetics, and genomics reportable cardiac diseases and pharmacogenomic biomarkers that have led to clinical recommendations and interventions. Furthermore, more than 80% of the participants (21) carried 1-3 genetic variants with an associated clinical guideline for an altered drug dosing or administration based on the FDA's table of pharmacogenomics. These results support WES potential not only to answer specific diagnostic questions presented by the relevant personal and/or family history but also to uncover clinically important genetic findings unrelated to the primary indication for sequencing.