Cat eye syndrome: Clinical, cytogenetics and familial findings in a large cohort of 43 patients highlighting the importance of congenital heart disease and inherited cases

Cat Eye Syndrome (CES) is a rare genetic disease caused by the presence of a small supernumerary marker chromosome derived from chromosome 22, which results in a partial tetrasomy of 22p-22q11.21. CES is classically defined by association of iris coloboma, anal atresia, and preauricular tags or pits, with high clinical and genetic heterogeneity. We conducted an international retrospective study of patients carrying genomic gain in the 22q11.21 chromosomal region upstream from LCR22-A identified using FISH, MLPA, and/or array-CGH. We report a cohort of 43 CES cases. We highlight that the clinical triad represents no more than 50% of cases. However, only 16% of CES patients presented with the three signs of the triad and 9% not present any of these three signs. We also highlight the importance of other impairments: cardiac anomalies are one of the major signs of CES (51% of cases), and high frequency of intellectual disability (47%). Ocular motility defects (45%), abdominal malformations (44%), ophthalmologic malformations (35%), and genitourinary tract defects (32%) are other frequent clinical features. We observed that sSMC is the most frequent chromosomal anomaly (91%) and we highlight the high prevalence of mosaic cases (40%) and the unexpectedly high prevalence of parental transmission of sSMC (23%). Most often, the transmitting parent has mild or absent features and carries the mosaic marker at a very low rate (<10%). These data allow us to better delineate the clinical phenotype associated with CES, which must be taken into account in the cytogenetic testing for this syndrome. These findings draw attention to the need for genetic counseling and the risk of recurrence.

Neuropathological hallmarks of antenatal mitochondrial diseases with a corpus callosum defect

Corpus callosum defects are frequent congenital cerebral disorders caused by mutations in more than 300 genes. These include genes implicated in corpus callosum development or function, as well as genes essential for mitochondrial physiology. However, in utero corpus callosum anomalies rarely raise a suspicion of mitochondrial disease and are characterized by a very large clinical heterogeneity.

Here, we report a detailed pathological and neuro-histopathological investigation of 9 fetuses from 4 unrelated families with prenatal onset of corpus callosum anomalies, sometimes associated with other cerebral or extra-cerebral defects. Next generation sequencing allowed the identification of novel pathogenic variants in 3 different nuclear genes previously reported in mitochondrial diseases: TIMMDC1, encoding a complex I assembly factor never involved before in corpus callosum defect; MRPS22, a protein of the small mitoribosomal subunit, and EARS2, the mitochondrial tRNA-glutamyl synthetase. The present report describes the antenatal histopathological findings in mitochondrial diseases and expands the genetic spectrum of antenatal corpus callosum anomalies establishing OXPHOS function as an important factor for corpus callosum biogenesis. We propose that, when observed, antenatal corpus callosum anomalies should raise suspicion of mitochondrial disease and prenatal genetic counseling should be considered.

Mild MDPL in a patient with a novel de novo missense variant in the Cys-B region of POLD1

DNA polymerase δ is one of the three main enzymes responsible for DNA replication. POLD1 heterozygous missense variants in the exonuclease domain result in a cancer predisposition phenotype. In contrast, heterozygous variants in POLD1 polymerase domain have more recently been shown to be the underlying basis of the distinct autosomal dominant multisystem lipodystrophy disorder, MDPL (mandibular hypoplasia, deafness, progeroid features, and lipodystrophy syndrome OMIM # 615381), most commonly a recurrent in-frame deletion of serine at position 604, accounting for 18 of the 21 reported cases of this condition. One patient with an unusually severe phenotype has been reported, caused by a de novo c. 3209 T > A, (p.(Ile1070Asn)) variant in the highly conserved CysB motif in the C-terminal of the POLD1 protein. This region has recently been shown to bind an iron-sulphur cluster of the 4Fe-4S type. This report concerns a novel de novo missense variant in the CysB region, c.3219 G > C, (p.(Ser1073Arg)) in a male child with a milder phenotype. Using in silico analysis in the context of the recently published structure of human Polymerase δ holoenzyme, we compared these and other variants which lie in close proximity but result in differing degrees of severity and varying features. We hypothesise that the c.3219 G > C, (p.(Ser1073Arg)) substitution likely causes reduced binding of the iron-sulphur cluster without significant disruption of protein structure, while the previously reported c.3209 T > A (p.(Ile1070Asn)) variant likely has a more profound impact on structure and folding in the region. Our analysis supports a central role for the CysB region in regulating POLD1 activity in health and disease.

Phenotypic spectrum and genomics of undiagnosed arthrogryposis multiplex congenita

BACKGROUND

Arthrogryposis multiplex congenita (AMC) is characterised by congenital joint contractures in two or more body areas. AMC exhibits wide phenotypic and genetic heterogeneity. Our goals were to improve the genetic diagnosis rates of AMC, to evaluate the added value of whole exome sequencing (WES) compared with targeted exome sequencing (TES) and to identify new genes in 315 unrelated undiagnosed AMC families.

METHODS

Several genomic approaches were used including genetic mapping of disease loci in multiplex or consanguineous families, TES then WES. Sanger sequencing was performed to identify or validate variants.

RESULTS

We achieved disease gene identification in 52.7% of AMC index patients including nine recently identified genes (CNTNAP1, MAGEL2, ADGRG6, ADCY6, GLDN, LGI4, LMOD3, UNC50 and SCN1A). Moreover, we identified pathogenic variants in ASXL3 and STAC3 expanding the phenotypes associated with these genes. The most frequent cause of AMC was a primary involvement of skeletal muscle (40%) followed by brain (22%). The most frequent mode of inheritance is autosomal recessive (66.3% of patients). In sporadic patients born to non-consanguineous parents (n=60), de novo dominant autosomal or X linked variants were observed in 30 of them (50%).

CONCLUSION

New genes recently identified in AMC represent 21% of causing genes in our cohort. A high proportion of de novo variants were observed indicating that this mechanism plays a prominent part in this developmental disease. Our data showed the added value of WES when compared with TES due to the larger clinical spectrum of some disease genes than initially described and the identification of novel genes.

A homozygous ATAD1 mutation impairs postsynaptic AMPA receptor trafficking and causes a lethal encephalopathy

Members of the AAA+ superfamily of ATPases are involved in the unfolding of proteins and disassembly of protein complexes and aggregates. ATAD1 encoding the ATPase family, AAA+ domain containing 1-protein Thorase plays an important role in the function and integrity of mitochondria and peroxisomes. Postsynaptically, Thorase controls the internalization of excitatory, glutamatergic AMPA receptors by disassembling complexes between the AMPA receptor-binding protein, GRIP1, and the AMPA receptor subunit GluA2. Using whole-exome sequencing, we identified a homozygous frameshift mutation in the last exon of ATAD1 [c.1070_1071delAT; p.(His357Argfs*15)] in three siblings who presented with a severe, lethal encephalopathy associated with stiffness and arthrogryposis. Biochemical and cellular analyses show that the C-terminal end of Thorase mutant gained a novel function that strongly impacts its oligomeric state, reduces stability or expression of a set of Golgi, peroxisomal and mitochondrial proteins and affects disassembly of GluA2 and Thorase oligomer complexes. Atad1-/- neurons expressing Thorase mutantHis357Argfs*15 display reduced amount of GluA2 at the cell surface suggesting that the Thorase mutant may inhibit the recycling back and/or reinsertion of AMPA receptors to the plasma membrane. Taken together, our molecular and functional analyses identify an activating ATAD1 mutation as a new cause of severe encephalopathy and congenital stiffness.

Autosomal recessive primary microcephaly due to ASPM mutations: An update

Autosomal recessive microcephaly or microcephaly primary hereditary (MCPH) is a genetically heterogeneous neurodevelopmental disorder characterized by a reduction in brain volume, indirectly measured by an occipitofrontal circumference (OFC) 2 standard deviations or more below the age- and sex-matched mean (-2SD) at birth and -3SD after 6 months, and leading to intellectual disability of variable severity. The abnormal spindle-like microcephaly gene (ASPM), the human ortholog of the Drosophila melanogaster "abnormal spindle" gene (asp), encodes ASPM, a protein localized at the centrosome of apical neuroprogenitor cells and involved in spindle pole positioning during neurogenesis. Loss-of-function mutations in ASPM cause MCPH5, which affects the majority of all MCPH patients worldwide. Here, we report 47 unpublished patients from 39 families carrying 28 new ASPM mutations, and conduct an exhaustive review of the molecular, clinical, neuroradiological, and neuropsychological features of the 282 families previously reported (with 161 distinct ASPM mutations). Furthermore, we show that ASPM-related microcephaly is not systematically associated with intellectual deficiency and discuss the association between the structural brain defects (strong reduction in cortical volume and surface area) that modify the cortical map of these patients and their cognitive abilities.

Phenomenological Transition of an Aluminum Surface in an Ionic Liquid and Its Beneficial Implementation in Batteries

Aluminum (Al) electrochemical dissolution in organic nonaqueous media and room temperature ionic liquids (RTILs) is partially hampered by the presence of a native oxide. In this work, Al activation in EMIm(HF)2.3F RTIL is reported. It was confirmed that as a result of the interaction of Al with the RTIL, a new film is formed instead of the pristine oxide layer. Aluminum surface modifications result in a transformation from a passive state to the active behavior of the metal. This was confirmed via the employment of electrochemical methods and characterization by XPS, AFM, and TEM. It was shown that the pristine oxide surface film dissolves in EMIm(HF)2.3F, allowing an Al-O-F layer to be formed instead. This newly built up layer dramatically restricts Al corrosion while enabling high rates of Al anodic dissolution. These beneficial features allow the implementation of Al as an anode in advanced portable power sources, such as aluminum-air batteries.

Variants in CUL4B are associated with cerebral malformations

Variants in cullin 4B (CUL4B) are a known cause of syndromic X-linked intellectual disability. Here, we describe an additional 25 patients from 11 families with variants in CUL4B. We identified nine different novel variants in these families and confirmed the pathogenicity of all nontruncating variants. Neuroimaging data, available for 15 patients, showed the presence of cerebral malformations in ten patients. The cerebral anomalies comprised malformations of cortical development (MCD), ventriculomegaly, and diminished white matter volume. The phenotypic heterogeneity of the cerebral malformations might result from the involvement of CUL-4B in various cellular pathways essential for normal brain development. Accordingly, we show that CUL-4B interacts with WDR62, a protein in which variants were previously identified in patients with microcephaly and a wide range of MCD. This interaction might contribute to the development of cerebral malformations in patients with variants in CUL4B.

New insights into genotype-phenotype correlation for GLI3 mutations

The phenotypic spectrum of GLI3 mutations includes autosomal dominant Greig cephalopolysyndactyly syndrome (GCPS) and Pallister-Hall syndrome (PHS). PHS was first described as a lethal condition associating hypothalamic hamartoma, postaxial or central polydactyly, anal atresia and bifid epiglottis. Typical GCPS combines polysyndactyly of hands and feet and craniofacial features. Genotype-phenotype correlations have been found both for the location and the nature of GLI3 mutations, highlighting the bifunctional nature of GLI3 during development. Here we report on the molecular and clinical study of 76 cases from 55 families with either a GLI3 mutation (49 GCPS and 21 PHS), or a large deletion encompassing the GLI3 gene (6 GCPS cases). Most of mutations are novel and consistent with the previously reported genotype-phenotype correlation. Our results also show a correlation between the location of the mutation and abnormal corpus callosum observed in some patients with GCPS. Fetal PHS observations emphasize on the possible lethality of GLI3 mutations and extend the phenotypic spectrum of malformations such as agnathia and reductional limbs defects. GLI3 expression studied by in situ hybridization during human development confirms its early expression in target tissues.

Loss-of-function mutations in RSPH1 cause primary ciliary dyskinesia with central-complex and radial-spoke defects

Primary ciliary dyskinesia (PCD) is a rare autosomal-recessive respiratory disorder resulting from defects of motile cilia. Various axonemal ultrastructural phenotypes have been observed, including one with so-called central-complex (CC) defects, whose molecular basis remains unexplained in most cases. To identify genes involved in this phenotype, whose diagnosis can be particularly difficult to establish, we combined homozygosity mapping and whole-exome sequencing in a consanguineous individual with CC defects. This identified a nonsense mutation in RSPH1, a gene whose ortholog in Chlamydomonas reinhardtii encodes a radial-spoke (RS)-head protein and is mainly expressed in respiratory and testis cells. Subsequent analyses of RSPH1 identified biallelic mutations in 10 of 48 independent families affected by CC defects. These mutations include splicing defects, as demonstrated by the study of RSPH1 transcripts obtained from airway cells of affected individuals. Wild-type RSPH1 localizes within cilia of airway cells, but we were unable to detect it in an individual with RSPH1 loss-of-function mutations. High-speed-videomicroscopy analyses revealed the coexistence of different ciliary beating patterns-cilia with a normal beat frequency but abnormal motion alongside immotile cilia or cilia with a slowed beat frequency-in each individual. This study shows that this gene is mutated in 20.8% of individuals with CC defects, whose diagnosis could now be improved by molecular screening. RSPH1 mutations thus appear as a major etiology for this PCD phenotype, which in fact includes RS defects, thereby unveiling the importance of RSPH1 in the proper building of CCs and RSs in humans.

Excess of neuromuscular spindles in a fetus with Costello syndrome: a clinicopathological report

The neuromuscular spindle (NMS) is a proprioceptive myofibrillar component of skeletal muscles that is necessary to maintain normal muscle tone and coordination. Recently, an excess of NMS has been reported as a congenital neuromuscular syndrome with a Noonan phenotype, now linked to Costello syndrome (CS). The vast majority of patients with CS have a de novo heterozygous mutation in the HRAS gene involved in the Ras/mitogen-activated protein kinase (MAPK) pathway. CS has many features in common with Noonan and cardiofaciocutaneous syndromes, also linked to activating mutations (but in other genes) of the Ras/MAPK pathway. This makes the orientation of molecular screening difficult. The observation of excess NMS in a 26-weeks'-gestation stillborn prompted us to screen the HRAS gene for mutation. The identification of a HRAS mutation made it possible to establish a diagnosis of CS. We conclude that the excess of NMS is the most reliable sign for the diagnosis of CS. Our findings also show the instrumental role of histological study of the skeletal muscles in the context of polyhydramnios and fetal hydrops.

Möbius Syndrome in a Neonate After Mifepristone and Misoprostol Elective Abortion Failure

Objective:

To report a case of a child born with Möbius syndrome following exposure in utero to mifepristone and misoprostol for elective abortion.

Case Summary:

In the seventh week of pregnancy, a woman was administered mifepristone 600 mg and, 2 days later, misoprostol 400 μg for abortion. One month later, despite significant metrorrhagia, an ultrasound examination showed ongoing gestation. At 33 weeks and 3 days of gestation, the woman gave birth to a male with left facial palsy, microretrognathia, and axial hypotonia related to Möbius syndrome.

Discussion:

Möbius syndrome is characterized by unilateral or bilateral palsy of the abducens (VI) and facial (VII) cranial nerves. Other cranial nerves (eg, the hypoglossal [XII]), craniofacial or orofacial anomalies, and limb malformations are often associated. The etiology of the Möbius syndrome remains largely unknown and probably involves multiple factors. The most likely etiological hypothesis is disruption of the developing vascular system, with transient ischemia (particularly in the vertebral arteries) and fetal hypoxia. A teratogenic cause of Möbius syndrome has been suggested. The critical period for the development of Möbius syndrome following teratogen exposure appears to be 5–8 weeks of gestation. To date, mifepristone alone does not appear to have induced Möbius syndrome. In contrast, oral or vaginal misoprostol administration can lead to a significant increase in Doppler-measured uterine artery resistance and may induce uterine contractions. If these occur during the critical embryonic period, they may cause flexion in the areas of the sixth and seventh cranial nerves and decreased blood flow.

Conclusions:

Ineffective use of mifepristone and misoprostol in the first trimester of pregnancy may be associated with a risk of Möbius syndrome, primarily due to misoprostol activity. Women with ongoing pregnancy after failed abortion with misoprostol administration should be informed of this risk.

Early maturation of evoked otoacoustic emissions and medial olivocochlear reflex in preterm neonates

The present study was designed to investigate the early maturation of the brainstem regulation of the cochlear function in preterm neonates. Evoked otoacoustic emissions (EOAE) and their regulation via the medial olivocochlear efferent (MOC) reflex were investigated in a large population of preterm neonates and compared with full-term neonates and young babies from birth to 4 y and school-aged children. In 28-wk preterm neonates, EOAE were seen in the mid-frequency range. These responses extended both to the low (down to 1025 Hz) and high (up to 6152 Hz) frequency ranges at 38 wk of gestational age and remained stable up to 4 mo. At this stage, the amplitude of EOAE overlapped adult values. EOAE amplitudes then decreased to reach adult values at 3 y of age. Maturation of MOC efferents innervating the outer hair cells was investigated by studying the suppressive effect of contralateral sound on the EOAE amplitudes (MOC reflex). The first MOC responses were recorded in preterm neonates of 32-33 wk of gestational age, reaching adult-like values at 37 wk of gestational age. The maximum effect of MOC efferent activation occurred between 2000 and 4000 Hz. These results suggest that, in humans, MOC efferents mature in utero. Thus, testing the MOC reflex may have a clinical relevance to detect an abnormal development of the auditory pathways, particularly of a brainstem circuitry not explored through conventional testing.

[Neonatal nonbacterial thrombotic endocarditis]

Nonbacterial thrombotic endocarditis is not widely known in neonates.

CASE REPORTS

We report three new cases which illustrate some specific aspects of this pathology. Respiratory distress with severe pulmonary hypertension, systemic hypotension and disseminated intravascular coagulopathy in a full-term newborn were characteristic findings.

CONCLUSION

An early echocardiography should lead to accurate diagnosis. Hypoxemia and genetic factors could be determining factors in its pathogenesis.

Constitutional mutations of the hSNF5/INI1 gene predispose to a variety of cancers

Biallelic, truncating mutations of the hSNF5/INI1 gene have recently been documented in malignant rhabdoid tumor (MRT), one of the most aggressive human cancers. This finding suggests that hSNF5/INI1 is a new tumor-suppressor gene for which germline mutations might predispose to cancer. We now report the presence of loss-of-function mutations of this gene in the constitutional DNA from affected members but not from healthy relatives in cancer-prone families. Furthermore, a constitutional mutation is documented in a patient with two successive primary cancers. In agreement with the two-hit model, the wild-type hSNF5/INI1 allele is deleted in the tumor DNA from mutation carriers. In all tested cases, DNA from parents demonstrated normal hSNF5/INI1 sequences, therefore indicating the de novo occurrence of the mutation, which was shown to involve the maternal allele in one case and the paternal allele in two other cases. These data indicate that constitutional mutation of the hSNF5/INI1 gene defines a new hereditary syndrome predisposing to renal or extrarenal MRT and to a variety of tumors of the CNS, including choroid plexus carcinoma, medulloblastoma, and central primitive neuroectodermal tumor. This condition, which we propose to term "rhabdoid predisposition syndrome," may account for previous observations of familial and multifocal cases of the aforementioned tumor types. It could also provide the molecular basis for cases of Li-Fraumeni syndrome without p53 germline mutations.

[Prenatal diagnosis of chylothorax]

Chylothorax is defined as the presence of lymph in the pleural space. Congenital chylothorax is one of the most frequent causes of fetal pleural effusion. It may be primary or secondary. Careful assessment of the etiology and of possible associated anomalies is required. Main complications are pulmonary hypoplasia, hydrops fetalis and the risk of premature delivery. Management is still a mater of controversy, the diagnosis of fetal pulmonary hypoplasia being difficult in utero. Factors such as gestational age, evolution of pleural effusion on two weeks, signs of seriousness (hydrops fetalis), and pulmonary expansion after pleural puncture may help the physician to choose between abstention, pleural tapping or long-term in utero drainage. Post natal treatment consists of pleural drainage and assisted ventilation in cases of respiratory distress, correction of metabolic and immune disorders and exclusive parenteral nutrition. Once chylothorax is resolved, formula feeding without long-chain triglycerides is allowed. If pleural effusion persists despite a well conducted treatment, albumin infusion and diuretics may be used before considering surgical treatment.

[Comparative evaluation of clinical and ultrasonographic screening of hip dislocation in Breton and Languedoc populations]

BACKGROUND

Congenital dislocation of the hip varies greatly in incidence among different regions. This work is aimed at comparing results of clinical investigation and ultrasonography of the hip in Languedoc-Roussillon and Brittany.

POPULATION AND METHODS

Two thousand eight hundred and twelve and 2,809 neonates admitted to Nîmes and Vannes hospitals respectively, were enrolled in a prospective study. Clinical examinations were made according to the protocol established by the "Groupe d' études en orthopédie pédiatrique". Ultrasound investigations were performed in every risk case.

RESULTS

No dislocation occurred in the 4946 neonates without risk factors. In the 675 neonates with risk factors, 213 ultrasonographic examinations were abnormal, more frequently in the Brittany group (P < 0.001); nine dislocations were observed. A familial history of hip dysplasia (P < 0.001) and the addition of two risk factors (P < 0.001) were more frequent in Brittany. One hundred and six cases required treatment, more frequently in Brittany (P < 0.001).

CONCLUSIONS

Some clinical risk factors and delayed ossification or hip dysplasia at ultrasound examination are significantly more frequent in Brittany. Clinical examination with selective ultrasonography is a reliable method, allowing early diagnosis and treatment of delayed dislocations.

Coexistent hereditary coproporphyria and congenital erythropoietic porphyria (Günther disease)

We present data on one patient with an inheritance pattern for two porphyrias. From her mother she inherited the trait of hereditary coproporphyria; from both parents she inherited the trait of congenital erythropoietic porphyria (Günther disease). Enzyme studies confirmed this new type of dual porphyria.

[Hereditary renal adysplasia. Apropos of 2 families]

Two families with hereditary renal adysplasia are reported. Transmission is dominant autosomal. There were no genital abnormalities.

[Validity of a specific bronchial provocation test with proteolytic enzymes in occupational bronchial asthma caused by enzymatic detergents]

Six asthmatic subjects exposed to enzymatic detergents derived from B. Licheniformis were examined by means of a specific Bronchial Provocative Test (sBPT) with solutions of the enzyme. All subjects, except for one, were positive to prick tests with solutions of the "crude" enzyme and with Alcalase, and showed high levels of specific IgE by RAST. The sBPT with solutions of the enzyme, administered by means of a Bird Mark 7 nebulyzer in IPPB with measurement of the delivered dose, showed a positive response in all 6 subjects. No positive result was obtained in 5 normal subjects and in 5 non exposed asthmatic patients, even at much higher doses of the delivered enzyme. The occupational-type sBPT showed only two positive results out of the 6 examined. A good relationship was observed between bronchial hyperresponsiveness and provocative dose of the enzyme. Therefore, the sBPT with solutions of the enzyme is proved to be highly sensitive and specific in confirming the diagnosis of occupational asthma due to proteolytic enzymes.