Young XLH Patients-Reported Experience with a Supportive Care Program.

Purpose: X-linked hypophosphatemia (XLH) is a rare, chronic, genetic condition characterized by renal phosphate wasting and abnormal bone and teeth mineralization. It represents a challenging and multifaceted disease that causes wide-ranging impacts on patients' lives. In this context, a scientific committee has designed a support initiative for patients treated for XLH: the aXess program. We sought to determine if a patient support program (PSP) could help XLH patients cope with their condition. Methods: During the 12 months of participation in the aXess program, XLH patients were contacted by phone by a nurse to coordinate their treatment, ensure treatment adherence, and provide motivational interviews. A Pediatric QOL inventory was conducted on all participants at enrollment (D0), at month 6, and month 12. Results: Altogether, a total of 59 patients were enrolled in the program. Most patients reported an improvement in QOL in all examined dimensions by month 12 (physical, emotional, social, and school, 85.4 ± 0.2 at month 12 versus 75.6 ± 0.3 at enrollment, p<0.05). Patients were very satisfied with the program, with a mean overall satisfaction score of 9.8 ± 0.6 (on a scale from 0 to 10) at month 6 and 9.2 ± 1.5 at month 12. Conclusion: Our findings indicate that this program might improve the QOL for patients with chronic conditions such as XLH through patient education, therapy adherence, motivational interviews, and frequent follow-up. It links the home environment and overall illness management, bringing patients, families, and caregivers together.

Changes in the clinical management of 5α-reductase type 2 and 17ß-hydroxysteroid dehydrogenase type 3 deficiencies in France.

Objectives: To examine the changes in diagnostic practices and clinical management of patients with 5α-reductase type 2 (SRD5A2) or 17ß-hydroxysteroid dehydrogenase type 3 (HSD17B3) deficiency since molecular diagnoses became available. Methods: Clinical, laboratory, and therapeutic data were retrieved from the medical records of 52 patients with a molecular diagnosis of SRD5A2 (n = 31) or HSD17B3 (n = 21) deficiency. Temporal trends regarding age at assessment and initial sex assignment over 1994-2020 were qualitatively analyzed. Age at molecular diagnosis was compared between two subgroups of patients according to their year of birth. Results: Fifty-eight percent (n = 30) patients were diagnosed during the perinatal period, 33% (n = 17) during infancy, and 9% (n = 5) during adolescence or adulthood. Over the studied period, the patients' age at initial assessment and diagnosis frankly decreased. The median (range) age at diagnostic confirmation was 10.5 (0-53.2) years for patients born before 2007 and 0.4 (0-9.3) years for those born in 2007 or later (P = 0.029). Genetic testing identified 27 different variants for the SRD5A2 gene (30% novel, n = 8) and 18 for the HSD17B3 gene (44% novel, n = 8). Before 2002, most patients were initially assigned as females (95%, n = 19), but this proportion dropped for those born later (44%, n = 14; P < 0.001). The influence of initial genital appearance on these decisions seemingly decreased in the most recent years. Therapeutic interventions differed according to the sex of rearing. Ten percent (n = 2) patients requested female-to-male reassignment during adulthood. Conclusion: This study showed, over the past two decades, a clear trend toward earlier diagnosis and assignment of affected newborns as males.

Genotype-phenotype Description of Vitamin D-dependent Rickets 1A: CYP27B1 p.(Ala129Thr) Variant Induces a Milder Disease.

INTRODUCTION: Vitamin D-dependent rickets type 1A (VDDR1A) is a rare genetic disease associated with loss-of-function variations in the gene encoding the vitamin D-activating enzyme 1α-hydroxylase (CYP27B1). Phenotype-genotype correlation is unclear. Long-term outcome data are lacking. The objective of this study was to describe characteristics and outcomes to search for a phenotype-genotype correlation. METHODS: We retrospectively collected clinical data, genetic features, and outcomes from 24 genetically confirmed cases from 10 French centers; results are presented as median (min-max). RESULTS: Clinical symptoms at diagnosis (age, 1.5 [0.5-8.7] years) were mainly bone and neurological abnormalities, and laboratory data showed hypocalcemia (1.97 [1.40-2.40] mmol/L), hypophosphatemia (-3.4 [-13.4 to (-)0.2] SD score for age), low 25OHD and low 1,25(OH)2D3, secondary hyperparathyroidism with PTH at 6.6 (1.3-13.7) times the upper limit for normal (ULN; PTH expressed as ULN to homogenize data presentation), and increased alkaline phosphatase (1968 [521-7000] IU/L). Bone radiographs were abnormal in 83% of patients. We identified 17 variations (11 missense, 3 frameshift, 2 truncating, and 1 acceptor splice site variations) in 19 families (homozygous state in 58% [11/19]). The partial loss-of-function variation p.(Ala129Thr) was associated with a milder phenotype: older age at diagnosis, higher serum calcium (2.26 vs 1.85 mmol/L), lower PTH (4.7 vs 7.5 ULN), and lower alkaline phosphatase (759 vs 2082 IU/L). Patients were treated with alfacalcidol. Clinical (skeletal, neurological), biochemical, and radiological outcomes were satisfactory, and complications occurred if there was bad adherence. CONCLUSION: Overall, our findings highlight good outcomes under substitutive treatment and the need of a closer follow-up of eyes, teeth, kidneys, and blood pressure in VDDR1A.

Presenting features and molecular genetics of primary hyperparathyroidism in the paediatric population.

AIM: To describe the presenting features and molecular genetics of primary hyperparathyroidism (PHPT) in the paediatric population. METHODS: Retrospective study of 63 children diagnosed with primary PHPT from 1998 to 2018. RESULTS: Compared to older children, infants were often asymptomatic (54% vs 15%, P = 0.002) with a milder form of PHPT. When symptomatic, children and adolescents mostly presented with non-specific complaints such as asthenia, depression, weight loss, vomiting or abdominal pain. A genetic cause of PHPT was identified in about half of this cohort (52%). The infancy period was almost exclusively associated with mutation in genes involved in the calcium-sensing receptor (CaSR) signalling pathway (i.e. CaSR and AP2S1 genes, 'CaSR group'; 94% of infants with mutations) whereas childhood and adolescence were associated with mutation in genes involved in parathyroid cell proliferation (i.e. MEN1, CDC73, CDKN1B and RET genes, 'cell proliferation group'; 69% of children and adolescents with mutations). Although serum calcium levels did not differ between the two groups (P = 0.785), serum PTH levels and the urinary calcium/creatinine ratio were significantly higher in 'cell proliferation group' patients compared to those in the 'CaSR group' (P = 0.001 and 0.028, respectively). CONCLUSION: Although far less common than in adults, PHPT can develop in children and is associated with significant morbidity. Consequently, this diagnosis should be considered in children with non-specific complaints and lead to monitoring of mineral homeostasis parameters. A genetic cause of PHPT can be identified in about half of these patients.

A targeted next-generation sequencing assay for the molecular diagnosis of genetic disorders with orodental involvement.

BACKGROUND: Orodental diseases include several clinically and genetically heterogeneous disorders that can present in isolation or as part of a genetic syndrome. Due to the vast number of genes implicated in these disorders, establishing a molecular diagnosis can be challenging. We aimed to develop a targeted next-generation sequencing (NGS) assay to diagnose mutations and potentially identify novel genes mutated in this group of disorders. METHODS: We designed an NGS gene panel that targets 585 known and candidate genes in orodental disease. We screened a cohort of 101 unrelated patients without a molecular diagnosis referred to the Reference Centre for Oro-Dental Manifestations of Rare Diseases, Strasbourg, France, for a variety of orodental disorders including isolated and syndromic amelogenesis imperfecta (AI), isolated and syndromic selective tooth agenesis (STHAG), isolated and syndromic dentinogenesis imperfecta, isolated dentin dysplasia, otodental dysplasia and primary failure of tooth eruption. RESULTS: We discovered 21 novel pathogenic variants and identified the causative mutation in 39 unrelated patients in known genes (overall diagnostic rate: 39%). Among the largest subcohorts of patients with isolated AI (50 unrelated patients) and isolated STHAG (21 unrelated patients), we had a definitive diagnosis in 14 (27%) and 15 cases (71%), respectively. Surprisingly, COL17A1 mutations accounted for the majority of autosomal-dominant AI cases. CONCLUSIONS: We have developed a novel targeted NGS assay for the efficient molecular diagnosis of a wide variety of orodental diseases. Furthermore, our panel will contribute to better understanding the contribution of these genes to orodental disease. TRIAL REGISTRATION NUMBERS: NCT01746121 and NCT02397824.

Mutations in the latent TGF-beta binding protein 3 (LTBP3) gene cause brachyolmia with amelogenesis imperfecta.

Inherited dental malformations constitute a clinically and genetically heterogeneous group of disorders. Here, we report on four families, three of them consanguineous, with an identical phenotype, characterized by significant short stature with brachyolmia and hypoplastic amelogenesis imperfecta (AI) with almost absent enamel. This phenotype was first described in 1996 by Verloes et al. as an autosomal recessive form of brachyolmia associated with AI. Whole-exome sequencing resulted in the identification of recessive hypomorphic mutations including deletion, nonsense and splice mutations, in the LTBP3 gene, which is involved in the TGF-beta signaling pathway. We further investigated gene expression during mouse development and tooth formation. Differentiated ameloblasts synthesizing enamel matrix proteins and odontoblasts expressed the gene. Study of an available knockout mouse model showed that the mutant mice displayed very thin to absent enamel in both incisors and molars, hereby recapitulating the AI phenotype in the human disorder.

Analysis of AP2S1, a calcium-sensing receptor regulator, in familial and sporadic isolated hypoparathyroidism.

BACKGROUND: Except after neck surgery, hypoparathyroidism is a rare disease caused by defects in genes involved in parathyroid gland development (TBX1/22q11.2 del, GCMB, GATA3, TBCE) or function [calcium sensing receptor (CASR), GNA11, PTH], or the autoimmune polyglandular syndrome type 1 (AIRE). Approximately 90% of sporadic cases and 30% of familial cases of isolated hypoparathyroidism remain unexplained. Recurrent missense mutations in AP2S1, a calcium-sensing receptor regulator, have been recently identified in familial hyperparathyroidism. AIM: The aim of the study was to investigate AP2S1 as a putative hypoparathyroidism-causing gene. METHODS: Sequencing analysis and quantitative genomic PCR of the AP2S1 gene in a large cohort of 10 index cases (from nine families) and 50 sporadic cases affected with isolated hypoparathyroidism were investigated. RESULTS AND CONCLUSIONS: None of the 60 patients presented with nucleotidic changes or copy number variation in the AP2S1 gene, thereby excluding AP2S1 defects as a frequent cause of isolated hypoparathyroidism.

Frasier syndrome, a potential cause of end-stage renal failure in childhood.

The diagnosis of Frasier syndrome is based on the association of male pseudohermaphroditism (as a result of gonadal dysgenesis), with steroid-resistant nephrotic syndrome due to focal and segmental glomerular sclerosis (FSGS), which progresses to end-stage renal failure (ESRF) during adolescence or adulthood. Frasier syndrome results from mutations in the Wilms' tumour suppressor gene WT1, which is responsible for alterations in male genital development and podocyte dysfunction. We describe the case of a 7-year-old girl who was referred to the paediatric emergency department with ESRF. Haemodialysis was started immediately because of severe hypertension and hyperkalaemia. In view of the fact that our patient had a past medical history of pseudohermaphroditism, we suspected that the acute presentation in ESRF may be related to a new diagnosis of Frasier syndrome. Our hypothesis was confirmed on examination of the medical records. There had been no medical follow-up for several years and, in particular, no renal imaging or functional assessment had ever been performed. This lack of surveillance explains why our patient presented with ESRF much earlier in this disease than expected and subsequently had to undergo kidney transplantation at a very young age.

Mutational analysis of steroidogenic factor 1 (NR5a1) in 24 boys with bilateral anorchia: a French collaborative study.

BACKGROUND Steroidogenic factor 1 (SF1/AdBP4/FTZF1, NR5A1) is a nuclear receptor transcription factor that plays a key role in regulating adrenal and gonadal development, steroidogenesis and reproduction. Recently, haploinsufficiency of SF1 has been described in several 46,XY individuals with mild gonadal dysgenesis and impaired androgenization, but normal adrenal function, suggesting that dosage-sensitive or domain-specific effects of SF1 action are important in human testicular development and function. Our objective was to investigate whether partial defects in SF1 function might be associated with milder male reproductive phenotypes, such as bilateral anorchia ('vanishing testis syndrome') and micropenis. METHODS This study involved mutational analysis of NR5A1 in 24 individuals with bilateral anorchia and micropenis from the French Collaborative Anorchia study, as well as in vitro functional studies of SF1-dependent transcriptional activation and computer modeling. RESULTS A novel heterozygous missense mutation (V355M) in SF1 was found in one boy with a micropenis and testicular regression syndrome. This non-synonymous change was found to affect a highly conserved amino acid within helix 7 of the ligand-binding domain of SF1. This V355M mutation did not affect stability or nuclear localization, but did result in an approximately 50% reduction in SF1 activity in several different assay systems. CONCLUSIONS In conclusion, heterozygous partial loss of function mutations in SF1 may be associated with bilateral anorchia ('vanishing testis syndrome') and micropenis in humans.

GH deficiency with central precocious puberty: a new rare disorder associated with a developmental defect of the hypothalamic-pituitary area.

CONTEXT: GH deficiency (GHD) associated with central precocious puberty (CPP) has been widely reported in cases of arachnoid cyst, septo-optic dysplasia, brain tumors, or after cerebral radiation therapy. However, idiopathic GHD associated with CPP has been reported in only one isolated case. OBJECTIVE: To evaluate the occurrence and clinical features of the association of nonacquired GHD and CPP. DESIGN AND SETTING: This was a retrospective multicenter study. PATIENTS AND METHODS: The study population was identified through a French nationwide multicenter network (about 3000 patients). We reviewed the medical records of all subjects diagnosed with nonacquired GHD and CPP, with or without developmental abnormalities of the hypothalamic-pituitary axis on cerebral magnetic resonance imaging (MRI), and without any known associated anomaly. RESULTS: We identified four patients with either isolated GHD (n=1) or multiple anterior pituitary hormone deficiencies (n=3). Clinical signs of CPP occurred at 6.4 +/- 2.3 years in boys and 7.5 +/- 0.5 years in girls, and GnRH analog therapy was started at 4.2 +/- 1.6 years after the initiation of recombinant human GH treatment. Cerebral MRI demonstrated ectopic neurohypophysis associated with anterior pituitary hypoplasia in three out of the four patients. The morphology and position of the anterior pituitary and neurohypophysis were normal in one patient who displayed a persistence of the craniopharyngeal canal. CONCLUSIONS: CPP is very rare in patients with nonacquired GHD and is mostly associated with developmental defects in the hypothalamic-pituitary area. Whether molecular mechanisms governing development and activation of the hypothalamic-pituitary axis share dependent factors remains to be explored.

Intensified and daily hemodialysis in children might improve statural growth.

In children conventional hemodialysis does not often improve growth. We determined linear growth in five children on in-center intensified and daily hemodialysis (IDd) regimen, with a mean age of 8 years 7 months at enrollment. Four of five were on growth hormone started for a median of 28.5 months before IDd. IDd was delivered 5 to 6 times weekly, for three hours each session. Mean follow up of IDd was 18.6 months. Dropout from IDd was kidney transplantation (n=4) or transfer to another center (n=1). IDd and free diet improved appetite, thereby protein intake, was above 2 g/kg/BW. Median weekly Kt/V(urea) was 9.1 (8.7 to 10.4). Predialysis phosphorus blood levels were higher at the start (2.04+/-0.34 mmol/L) than at end of IDd (1.39+/-0.41 mmol/L) without need for carbonate of calcium in four of five cases. During conventional dialysis ht SDS decreased from -0.8 to -1.44, which occurred predominantly before rhGH start. Conversion to IDd significantly increased growth velocity to a mean of 13 cm/year (10.3-18) with a mean change of +1.84 ht SDS/year (0.4 to 2.7). This preliminary report suggests the potential efficacy of IDd regimen in promising growth velocity, either directly from a higher dialysis dose or indirectly through an improved nutritional status.