Identification of a novel CFAP61 homozygous splicing variant associated with multiple morphological abnormalities of the flagella.

In this study, we investigated the role of a newly identified homozygous variant (c.1245 + 6T > C) in the CFAP61 gene in the development of multiple morphologically abnormal flagella (MMAF) in an infertile patient. Using exome sequencing, we identified this variant, which led to exon 12 skipping and the production of a truncated CFAP61 protein. Transmission electron microscopy analysis of the patient's spermatozoa revealed various flagellar abnormalities, including defective nuclear chromatin condensation, axoneme disorganization, and mitochondria embedded in residual cytoplasmic droplets. Despite a fertilization rate of 83.3% through ICSI, there was no successful pregnancy due to poor embryo quality.Our findings suggest a link between the identified CFAP61 variant and MMAF, indicating potential disruption in radial spokes' assembly or function crucial for normal ciliary motility. Furthermore, nearly half of the observed sperm heads displayed chromatin condensation defects, possibly contributing to the low blastulation rate. This case underscores the significance of genetic counseling and testing, particularly for couples dealing with infertility and MMAF. Early identification of such genetic variants can guide appropriate interventions and improve reproductive outcomes.

Results and perinatal outcomes from 189 ICSI cycles of couples with asthenozoospermic men and flagellar defects assessed by transmission electron microscopy.

RESEARCH QUESTION: Do patients presenting with flagella ultrastructural defects as assessed by electron microscopy, and defined within three phenotypes (dysplasia of the fibrous sheath [DFS], primary flagellar dyskinesia [PFD] and non-specific flagellar abnormalities [NSFA]), have decreased chances of success in intracytoplasmic sperm injection (ICSI) or adverse obstetric and neonatal outcomes? DESIGN: Retrospective analysis of 189 ICSI cycles from 80 men with spermatozoa flagellum ultrastructural defects (DFS [n = 16]; PFD [n = 14]; NSFA [n = 50] compared with a control group (n = 97). Cycles were cumulatively analysed. All fresh and frozen embryo transfers resulting from each ICSI attempt were included. The effect of transmission electron microscopy (TEM) phenotype on the main ICSI outcomes was assessed by a multivariate logistic regression combined with a generalized linear mixed model to account for the non-independence of the observations. RESULTS: No predictive value of TEM phenotype was found on the main outcomes of ICSI, namely fertilization rates, pregnancy and delivery rates, and cumulative pregnancy and delivery rates. Cumulative pregnancy rates ranged from 29.0-43.3% in the different TEM phenotype subgroups compared with 36.8% in the control group. Cumulative live birth rates ranged from 24.6-36.7% compared with 31.4% in the control group. No increase was found in miscarriages, preterm births, low birth weights or birth abnormalities. CONCLUSIONS: Data on the cumulative chances of success in ICSI of patients with ultrastructural flagellar defects, a rare cause of male infertility often associated with an underlying genetic cause, are reassuring, as are obstetrical and neonatal outcomes in this population.

Psychosocial Impact of Predictive Genetic Testing in Hereditary Heart Diseases: The PREDICT Study.

Predictive genetic testing (PGT) is offered to asymptomatic relatives at risk of hereditary heart disease, but the impact of result disclosure has been little studied. We evaluated the psychosocial impacts of PGT in hereditary heart disease, using self-report questionnaires (including the State-Trait Anxiety Inventory) in 517 adults, administered three times to the prospective cohort (PCo: n = 264) and once to the retrospective cohort (RCo: n = 253). The main motivations for undergoing PGT were "to remove doubt" and "for their children". The level of anxiety increased between pre-test and result appointments (p <0.0001), returned to baseline after the result (PCo), and was moderately elevated at 4.4 years (RCo). Subjects with a history of depression or with high baseline anxiety were more likely to develop anxiety after PGT result (p = 0.004 and p <0.0001, respectively), whatever it was. Unfavourable changes in professional and/or family life were observed in 12.4% (PCo) and 18.7% (RCo) of subjects. Few regrets about PGT were expressed (0.8% RCo, 2.3% PCo). Medical benefit was not the main motivation, which emphasises the role of pre/post-test counselling. When PGT was performed by expert teams, the negative impact was modest, but careful management is required in specific categories of subjects, whatever the genetic test result.

Systematic thyroid screening in myotonic dystrophy: link between thyroid volume and insulin resistance.

BACKGROUND: Myotonic dystrophy (DM1), a neuromuscular disease related to DMPK gene mutations, is associated to endocrine disorders and cancer. A routine endocrine work-up, including thyroid ultrasound (US), was conducted in 115 genetically-proven DM1 patients in a neuromuscular reference center. The aim of this study was to determine the prevalence and the causes of US thyroid abnormalities in DM1. RESULTS: In the whole population (age 45.1 ± 12.2 years, 61.7% female), palpable nodules or goiters were present in 29.2%. The percentage of US goiter (thyroid volume > 18 mL) and US nodules were, respectively, 38.3 and 60.9%. Sixteen of the 115 patients had a thyroidectomy, after 22 fine-needle aspiration cytology guided by thyroid imaging reporting and data system (TIRADS) classification. Six micro- (1/6 pT3) and 3 macro-papillary thyroid carcinoma (PTCs) (2/3 intermediate risk) were diagnosed (7.9% of 115). Thyroid US led to the diagnosis of 4 multifocal and 2 unifocal (including 1 macro-PTC) non-palpable PTCs. Ultrasound thyroid volume was positively correlated to body mass index (BMI) (p = 0.015) and parity (p = 0.036), and was inversely correlated to TSH (p < 0.001) and vitamin D levels (p = 0.023). The BMI, the frequencies of glucose intolerance and PTC were significantly higher in UsGoiter versus non-UsGoiter groups. CONCLUSION: In this systematically screened DM1 cohort, the frequency of UsGoiter, mainly associated to BMI, was about 40%, US nodules 60%, thyroidectomies 13-14%, and PTCs 8%, two-thirds of them being micro-PTCs with good prognosis. Therefore, a systematic screening remains debatable. A targeted US screening in case of clinical abnormality or high BMI seems more appropriate.

Functional assessment of creatine transporter in control and X-linked SLC6A8-deficient fibroblasts.

Creatine transporter is currently the focus of renewed interest with emerging roles in brain neurotransmission and physiology, and the bioenergetics of cancer metastases. We here report on amendments of a standard creatine uptake assay which might help clinical chemistry laboratories to extend their current range of measurements of creatine and metabolites in body fluids to functional enzyme explorations. In this respect, short incubation times and the use of a stable-isotope-labeled substrate (D3-creatine) preceded by a creatine wash-out step from cultured fibroblast cells by removal of fetal bovine serum (rich in creatine) from the incubation medium are recommended. Together, these measures decreased, by a first order of magnitude, creatine concentrations in the incubation medium at the start of creatine-uptake studies and allowed to functionally discriminate between 4 hemizygous male and 4 heterozygous female patients with X-linked SLC6A8 deficiency, and between this cohort of eight patients and controls. The functional assay corroborated genetic diagnosis of SLC6A8 deficiency. Gene anomalies in our small cohort included splicing site (c.912G > A [p.Ile260_Gln304del], c.778-2A > G and c.1495 + 2 T > G), substitution (c.407C > T) [p.Ala136Val] and deletion (c.635_636delAG [p.Glu212Valfs*84] and c.1324delC [p.Gln442Lysfs*21]) variants with reduced creatine transporter function validating their pathogenicity, including that of a previously unreported c.1324delC variant. The present assay adaptations provide an easy, reliable and discriminative manner for exploring creatine transporter activity and disease variations. It might apply to drug testing or other evaluations in the genetic and metabolic horizons covered by the emerging functions of creatine and its transporter, in a way, however, requiring and completed by additional studies on female patients and blood-brain barrier permeability properties of selected compounds. As a whole, the proposed assay of creatine transporter positively adds to currently existing measurements of this transporter activity, and determining on a large scale the extent of its exact suitability to detect female patients should condition in the future its transfer in clinical practice.

Affected female carriers of MTM1 mutations display a wide spectrum of clinical and pathological involvement: delineating diagnostic clues.

X-linked myotubular myopathy (XLMTM), a severe congenital myopathy, is caused by mutations in the MTM1 gene located on the X chromosome. A majority of affected males die in the early postnatal period, whereas female carriers are believed to be usually asymptomatic. Nevertheless, several affected females have been reported. To assess the phenotypic and pathological spectra of carrier females and to delineate diagnostic clues, we characterized 17 new unrelated affected females and performed a detailed comparison with previously reported cases at the clinical, muscle imaging, histological, ultrastructural and molecular levels. Taken together, the analysis of this large cohort of 43 cases highlights a wide spectrum of clinical severity ranging from severe neonatal and generalized weakness, similar to XLMTM male, to milder adult forms. Several females show a decline in respiratory function. Asymmetric weakness is a noteworthy frequent specific feature potentially correlated to an increased prevalence of highly skewed X inactivation. Asymmetry of growth was also noted. Other diagnostic clues include facial weakness, ptosis and ophthalmoplegia, skeletal and joint abnormalities, and histopathological signs that are hallmarks of centronuclear myopathy such as centralized nuclei and necklace fibers. The histopathological findings also demonstrate a general disorganization of muscle structure in addition to these specific hallmarks. Thus, MTM1 mutations in carrier females define a specific myopathy, which may be independent of the presence of an XLMTM male in the family. As several of the reported affected females carry large heterozygous MTM1 deletions not detectable by Sanger sequencing, and as milder phenotypes present as adult-onset limb-girdle myopathy, the prevalence of this myopathy is likely to be greatly underestimated. This report should aid diagnosis and thus the clinical management and genetic counseling of MTM1 carrier females. Furthermore, the clinical and pathological history of this cohort may be useful for therapeutic projects in males with XLMTM, as it illustrates the spectrum of possible evolution of the disease in patients surviving long term.

Incomplete penetrance and phenotypic variability of 6q16 deletions including SIM1.

6q16 deletions have been described in patients with a Prader-Willi-like (PWS-like) phenotype. Recent studies have shown that certain rare single-minded 1 (SIM1) loss-of-function variants were associated with a high intra-familial risk for obesity with or without features of PWS-like syndrome. Although SIM1 seems to have a key role in the phenotype of patients carrying 6q16 deletions, some data support a contribution of other genes, such as GRIK2, to explain associated behavioural problems. We describe 15 new patients in whom de novo 6q16 deletions were characterised by comparative genomic hybridisation or single-nucleotide polymorphism (SNP) array analysis, including the first patient with fetopathological data. This fetus showed dysmorphic facial features, cerebellar and cerebral migration defects with neuronal heterotopias, and fusion of brain nuclei. The size of the deletion in the 14 living patients ranged from 1.73 to 7.84 Mb, and the fetus had the largest deletion (14 Mb). Genotype-phenotype correlations confirmed the major role for SIM1 haploinsufficiency in obesity and the PWS-like phenotype. Nevertheless, only 8 of 13 patients with SIM1 deletion exhibited obesity, in agreement with incomplete penetrance of SIM1 haploinsufficiency. This study in the largest series reported to date confirms that the PWS-like phenotype is strongly linked to 6q16.2q16.3 deletions and varies considerably in its clinical expression. The possible involvement of other genes in the 6q16.2q16.3-deletion phenotype is discussed.

Genetic and clinical specificity of 26 symptomatic carriers for dystrophinopathies at pediatric age.

The molecular basis underlying the clinical variability in symptomatic Duchenne muscular dystrophy (DMD) carriers are still to be precised. We report 26 cases of early symptomatic DMD carriers followed in the French neuromuscular network. Clinical presentation, muscular histological analysis and type of gene mutation, as well as X-chromosome inactivation (XCI) patterns using DNA extracted from peripheral blood or muscle are detailed. The initial symptoms were significant weakness (88%) or exercise intolerance (27%). Clinical severity varied from a Duchenne-like progression to a very mild Becker-like phenotype. Cardiac dysfunction was present in 19% of the cases. Cognitive impairment was worthy of notice, as 27% of the carriers are concerned. The muscular analysis was always contributive, revealing muscular dystrophy (83%), mosaic in immunostaining (81%) and dystrophin abnormalities in western blot analysis (84%). In all, 73% had exonic deletions or duplications and 27% had point mutations. XCI pattern was biased in 62% of the cases. In conclusion, we report the largest series of manifesting DMD carriers at pediatric age and show that exercise intolerance and cognitive impairment may reveal symptomatic DMD carriers. The complete histological and immunohistological study of the muscle is the key of the diagnosis leading to the dystrophin gene analysis. Our study shows also that cognitive impairment in symptomatic DMD carriers is associated with mutations in the distal part of the DMD gene. XCI study does not fully explain the mechanisms as well as the wide spectrum of clinical phenotype, though a clear correlation between the severity of the phenotype and inactivation bias was observed.

Insights into genotype-phenotype correlations in spinal muscular atrophy: a retrospective study of 103 patients.

Spinal muscular atrophy (SMA) is an autosomal recessive disorder associated with homozygous deletion of the survival motor neuron 1 gene (SMN1). Its centromeric copy gene, SMN2, is the major modifying factor. However, the genotype-phenotype correlation is incomplete and is therefore not useful in clinical practice. We studied a cohort of 103 patients in order to refine this correlation. In addition to standard disease severity data, we collected three additional criteria: age at death; brainstem involvement; and loss of ambulation. Gene dosage analysis was conducted by multiplex ligation-dependent probe amplification (MLPA). SMN2 copynumber was highly correlated with survival duration in SMA type I and ambulation conservation or loss in type III. Among SMA severity groups, it was not significantly different in cases with brainstem involvement. Although the SMN2 copynumber could provide prognostic indications, clinical discrepancies still exist among patients, suggesting the existence of unidentified modifying factors.

Kallmann syndrome: mutations in the genes encoding prokineticin-2 and prokineticin receptor-2.

Kallmann syndrome combines anosmia, related to defective olfactory bulb morphogenesis, and hypogonadism due to gonadotropin-releasing hormone deficiency. Loss-of-function mutations in KAL1 and FGFR1 underlie the X chromosome-linked form and an autosomal dominant form of the disease, respectively. Mutations in these genes, however, only account for approximately 20% of all Kallmann syndrome cases. In a cohort of 192 patients we took a candidate gene strategy and identified ten and four different point mutations in the genes encoding the G protein-coupled prokineticin receptor-2 (PROKR2) and one of its ligands, prokineticin-2 (PROK2), respectively. The mutations in PROK2 were detected in the heterozygous state, whereas PROKR2 mutations were found in the heterozygous, homozygous, or compound heterozygous state. In addition, one of the patients heterozygous for a PROKR2 mutation was also carrying a missense mutation in KAL1, thus indicating a possible digenic inheritance of the disease in this individual. These findings reveal that insufficient prokineticin-signaling through PROKR2 leads to abnormal development of the olfactory system and reproductive axis in man. They also shed new light on the complex genetic transmission of Kallmann syndrome.

Metaphyseal chondrodysplasia with cone-shaped epiphyses: a specific form involving the lower limbs.

Three unrelated patients affected by a characteristic metaphyseal chondrodysplasia with cup-shaped metaphyses of the knees are described. Lower femoral and upper tibial cone-shaped epiphyses were embedded in the metaphyses. Main clinical features are short stature, shortening of the lower limbs, limitation of knee extension, and normal hands length. Radiographs of skull, spine, and hands showed no abnormality. This particular appearance of the knees has been seldom described in acquired disease such as repeated injuries, meningococcemia, scurvy, and hypervitaminosis A. Metaphyseal dysplasias with these distinctive radiological findings of the knees are uncommon. Differential diagnosis includes trichoscyphodysplasia and acroscyphodysplasia among others. Two other cases reported by Kozlowski showed the most similarities to our three cases and defined a new form of metaphyseal dysplasia with specific lower limbs involvement and cup-shaped metaphyses.