Carpenter syndrome in a patient from Tanzania.

Carpenter syndrome (acrocephalopolysyndactyly type II) is a rare autosomal recessive disorder. It was clinically diagnosed in a female baby with polysyndactyly and craniosynostosis in a referral clinic in Northern Tanzania. In the RAB23 gene, a previously described homozygous variant c.82C>T p.(Arg28*) was detected that results in a premature stop codon. Both parents were demonstrated to be heterozygous carriers of this variant. Herewith, its pathogenicity is proved. A literature search suggests this is the first molecularly confirmed case of Carpenter syndrome in continental Africa.

Ellis-van Creveld syndrome in a patient from Tanzania.

We report an African infant with Ellis-van Creveld (EVC) syndrome. EVC syndrome is a chondral and ectodermal dysplasia with autosomal recessive transmission. The baby presented with polydactyly, short limbs and atrioventricular septal defect, but was withdrawn from clinical follow up for the first year of life. Initial hematological abnormalities could not be explained and normalized later. EVC syndrome was confirmed by genetic analysis that showed two pathogenic mutations in the EVC2 gene, c.653_654del, p.Val218Glyfs*12 in exon 5, and c.2710C>T, p.Gln904* in exon 16. The variant c.653_654del; p.Val218Glyfs*12 in exon 5 has not been described before. Our review of medical literature suggested this is the first molecularly confirmed case of EVC syndrome in sub-Saharan Africa.

Mutations in MED12 cause X-linked Ohdo syndrome.

Ohdo syndrome comprises a heterogeneous group of disorders characterized by intellectual disability (ID) and typical facial features, including blepharophimosis. Clinically, these blepharophimosis-ID syndromes have been classified in five distinct subgroups, including the Maat-Kievit-Brunner (MKB) type, which, in contrast to the others, is characterized by X-linked inheritance and facial coarsening at older age. We performed exome sequencing in two families, each with two affected males with Ohdo syndrome MKB type. In the two families, MED12 missense mutations (c.3443G>A [p.Arg1148His] or c.3493T>C [p.Ser1165Pro]) segregating with the phenotype were identified. Upon subsequent analysis of an additional cohort of nine simplex male individuals with Ohdo syndrome, one additional de novo missense change (c.5185C>A [p.His1729Asn]) in MED12 was detected. The occurrence of three different hemizygous missense mutations in three unrelated families affected by Ohdo syndrome MKB type shows that mutations in MED12 are the underlying cause of this X-linked form of Ohdo syndrome. Together with the recently described KAT6B mutations resulting in Ohdo syndrome Say/Barber/Biesecker/Young/Simpson type, our findings point to aberrant chromatin modification as being central to the pathogenesis of Ohdo syndrome.

Mutations in the gene encoding the 3'-5' DNA exonuclease TREX1 cause Aicardi-Goutières syndrome at the AGS1 locus.

Aicardi-Goutières syndrome (AGS) presents as a severe neurological brain disease and is a genetic mimic of the sequelae of transplacentally acquired viral infection. Evidence exists for a perturbation of innate immunity as a primary pathogenic event in the disease phenotype. Here, we show that TREX1, encoding the major mammalian 3' --> 5' DNA exonuclease, is the AGS1 gene, and AGS-causing mutations result in abrogation of TREX1 enzyme activity. Similar loss of function in the Trex1(-/-) mouse leads to an inflammatory phenotype. Our findings suggest an unanticipated role for TREX1 in processing or clearing anomalous DNA structures, failure of which results in the triggering of an abnormal innate immune response.

Ciliopathies with skeletal anomalies and renal insufficiency due to mutations in the IFT-A gene WDR19.

A subset of ciliopathies, including Sensenbrenner, Jeune, and short-rib polydactyly syndromes are characterized by skeletal anomalies accompanied by multiorgan defects such as chronic renal failure and retinitis pigmentosa. Through exome sequencing we identified compound heterozygous mutations in WDR19 in a Norwegian family with Sensenbrenner syndrome. In a Dutch family with the clinically overlapping Jeune syndrome, a homozygous missense mutation in the same gene was found. Both families displayed a nephronophthisis-like nephropathy. Independently, we also identified compound heterozygous WDR19 mutations by exome sequencing in a Moroccan family with isolated nephronophthisis. WDR19 encodes IFT144, a member of the intraflagellar transport (IFT) complex A that drives retrograde ciliary transport. We show that IFT144 is absent from the cilia of fibroblasts from one of the Sensenbrenner patients and that ciliary abundance and morphology is perturbed, demonstrating the ciliary pathogenesis. Our results suggest that isolated nephronophthisis, Jeune, and Sensenbrenner syndromes are clinically overlapping disorders that can result from a similar molecular cause.

Deficiency of UBR1, a ubiquitin ligase of the N-end rule pathway, causes pancreatic dysfunction, malformations and mental retardation (Johanson-Blizzard syndrome).

Johanson-Blizzard syndrome (OMIM 243800) is an autosomal recessive disorder that includes congenital exocrine pancreatic insufficiency, multiple malformations such as nasal wing aplasia, and frequent mental retardation. We mapped the disease-associated locus to chromosome 15q14-21.1 and identified mutations, mostly truncating ones, in the gene UBR1 in 12 unrelated families with Johanson-Blizzard syndrome. UBR1 encodes one of at least four functionally overlapping E3 ubiquitin ligases of the N-end rule pathway, a conserved proteolytic system whose substrates include proteins with destabilizing N-terminal residues. Pancreas of individuals with Johanson-Blizzard syndrome did not express UBR1 and had intrauterine-onset destructive pancreatitis. In addition, we found that Ubr1(-/-) mice, whose previously reported phenotypes include reduced weight and behavioral abnormalities, had an exocrine pancreatic insufficiency, with impaired stimulus-secretion coupling and increased susceptibility to pancreatic injury. Our findings indicate that deficiency of UBR1 perturbs the pancreas' acinar cells and other organs, presumably owing to metabolic stabilization of specific substrates of the N-end rule pathway.

Novel CTR9 germline pathogenic splice site variant in siblings with Wilms tumor from Tanzania.

Wilms tumor is the most common childhood renal malignancy. Though mostly non-genetic, it can be syndromic with the involvement of many Wilms tumor predisposing genes and non-syndromic with the involvement of four genes: WT1, REST, TRIM28, and CTR9. Familial and bilateral Wilms tumors do occur, but these are rare. So far, four Wilms tumor families with pathogenic variants in the CTR9 gene have been described, all (presumably) inherited from unaffected fathers, and three leading to deletion of exon 9. We are reporting female siblings, of whom one has a bilateral Wilms tumor, with a novel pathogenic splice site variant in the CTR9 gene, leading to deletion of exon 9, and inherited from their asymptomatic father. The loss of heterozygosity in the tumor was confirmed. In conclusion, CTR9 pathogenic variants are a very rare cause of Wilms tumors and typically result in familial Wilms tumors.

Disruption of the podosome adaptor protein TKS4 (SH3PXD2B) causes the skeletal dysplasia, eye, and cardiac abnormalities of Frank-Ter Haar Syndrome.

Frank-Ter Haar syndrome (FTHS), also known as Ter Haar syndrome, is an autosomal-recessive disorder characterized by skeletal, cardiovascular, and eye abnormalities, such as increased intraocular pressure, prominent eyes, and hypertelorism. We have conducted homozygosity mapping on patients representing 12 FTHS families. A locus on chromosome 5q35.1 was identified for which patients from nine families shared homozygosity. For one family, a homozygous deletion mapped exactly to the smallest region of overlapping homozygosity, which contains a single gene, SH3PXD2B. This gene encodes the TKS4 protein, a phox homology (PX) and Src homology 3 (SH3) domain-containing adaptor protein and Src substrate. This protein was recently shown to be involved in the formation of actin-rich membrane protrusions called podosomes or invadopodia, which coordinate pericellular proteolysis with cell migration. Mice lacking Tks4 also showed pronounced skeletal, eye, and cardiac abnormalities and phenocopied the majority of the defects associated with FTHS. These findings establish a role for TKS4 in FTHS and embryonic development. Mutation analysis revealed five different homozygous mutations in SH3PXD2B in seven FTHS families. No SH3PXD2B mutations were detected in six other FTHS families, demonstrating the genetic heterogeneity of this condition. Interestingly however, dermal fibroblasts from one of the individuals without an SH3PXD2B mutation nevertheless expressed lower levels of the TKS4 protein, suggesting a common mechanism underlying disease causation.

Mutations in DYNC1H1 cause severe intellectual disability with neuronal migration defects.

BACKGROUND: DYNC1H1 encodes the heavy chain protein of the cytoplasmic dynein 1 motor protein complex that plays a key role in retrograde axonal transport in neurons. Furthermore, it interacts with the LIS1 gene of which haploinsufficiency causes a severe neuronal migration disorder in humans, known as classical lissencephaly or Miller-Dieker syndrome. AIM: To describe the clinical spectrum and molecular characteristics of DYNC1H1 mutations. METHODS: A family based exome sequencing approach was used to identify de novo mutations in patients with severe intellectual disability. RESULTS: In this report the identification of two de novo missense mutations in DYNC1H1 (p.Glu1518Lys and p.His3822Pro) in two patients with severe intellectual disability and variable neuronal migration defects is described. CONCLUSION: Since an autosomal dominant mutation in DYNC1H1 was previously identified in a family with the axonal (type 2) form of Charcot- Marie-Tooth (CMT2) disease and mutations in Dync1h1 in mice also cause impaired neuronal migration in addition to neuropathy, these data together suggest that mutations in DYNC1H1 can lead to a broad phenotypic spectrum and confirm the importance of DYNC1H1 in both central and peripheral neuronal functions.

Mutations in a new member of the chromodomain gene family cause CHARGE syndrome.

CHARGE syndrome is a common cause of congenital anomalies affecting several tissues in a nonrandom fashion. We report a 2.3-Mb de novo overlapping microdeletion on chromosome 8q12 identified by array comparative genomic hybridization in two individuals with CHARGE syndrome. Sequence analysis of genes located in this region detected mutations in the gene CHD7 in 10 of 17 individuals with CHARGE syndrome without microdeletions, accounting for the disease in most affected individuals.

Mutations in the polyglutamine binding protein 1 gene cause X-linked mental retardation.

We found mutations in the gene PQBP1 in 5 of 29 families with nonsyndromic (MRX) and syndromic (MRXS) forms of X-linked mental retardation (XLMR). Clinical features in affected males include mental retardation, microcephaly, short stature, spastic paraplegia and midline defects. PQBP1 has previously been implicated in the pathogenesis of polyglutamine expansion diseases. Our findings link this gene to XLMR and shed more light on the pathogenesis of this common disorder.

Subtelomeric chromosomal rearrangements in a large cohort of unexplained intellectually disabled individuals in Indonesia: A clinical and molecular study.

CONTEXT: Unbalanced subtelomeric chromosomal rearrangements are often associated with intellectual disability (ID) and malformation syndromes. The prevalence of such rearrangements has been reported to be 5-9% in ID populations. AIMS: To study the prevalence of subtelomeric rearrangements in the Indonesian ID population. MATERIALS AND METHODS: We tested 436 subjects with unexplained ID using multiplex ligation dependent probe amplification (MLPA) using the specific designed sets of probes to detect human subtelomeric chromosomal imbalances (SALSA P070 and P036D). If necessary, abnormal findings were confirmed by other MLPA probe kits, fluorescent in situ hybridization or Single Nucleotide Polymorphism array. RESULTS: A subtelomeric aberration was identified in 3.7% of patients (16/436). Details on subtelomeric aberrations and confirmation analyses are discussed. CONCLUSION: This is the first study describing the presence of subtelomeric rearrangements in individuals with ID in Indonesia. Furthermore, it shows that also in Indonesia such abnormalities are a prime cause of ID and that in developing countries with limited diagnostic services such as Indonesia, it is important and feasible to uncover the genetic etiology in a significant number of cases with ID.

Novel likely pathogenic variant in NR5A1 gene in a Tanzanian child with 46,XY differences of sex development, inherited from the mosaic father.

Summary: Pathogenic variants in the nuclear receptor subfamily 5 group A member 1 gene (NR5A1), which encodes steroidogenic factor 1 (SF1), result in 46,XY and 46,XX differences of sex development (DSD). In 46,XY individuals with a pathogenic variant in the NR5A1 gene a variable phenotype ranging from mild to severe is seen, including adrenal failure, testis dysgenesis, androgen synthesis defects, hypospadias and anorchia with microphallus and infertility. We report the clinical, endocrinological and genetic characteristics of a patient with 46,XY DSD with a novel likely pathogenic missense variant in the NR5A1 gene. A retrospective evaluation of the medical history, physical examination, limited endocrinological laboratory analysis and genetic analysis with DSD gene panel testing was performed. A 1.5-month-old individual was referred with ambiguous genitalia. The karyotype was 46,XY. The endocrinological analyses were within normal male reference including a normal response of cortisol within an adrenocorticotropic hormone test. A novel heterozygous missense variant c.206G>C p.(Arg69Pro) in the NR5A1 gene was detected. This variant was present in mosaic form (~20%) in his unaffected father. Because another missense variant at the same position and other missense variants involving the same highly conserved codon have been reported, we consider this NR5A1 variant in this 46,XY DSD patient as likely pathogenic in accordance with the ACMG/AMP 2015 guidelines causing ambiguous genitalia but no adrenal insufficiency. This variant was inherited from the apparently unaffected mosaic father, which might have implications for the recurrence risk in this family. Learning points: The importance of performing trio (patient and parents) sequencing is crucial in pointing out the origin of inheritance. In a 46,XY differences of sex development patient, a normal adrenal function does not rule out an NR5A1 mutation. With the support of a dedicated overseas institute partnership, we could solve this complex clinical case by molecular diagnosis in a resource-limited setting.

Assessment of left ventricular geometrical patterns and function among hypertensive patients at a tertiary hospital, Northern Tanzania.

BACKGROUND: With hypertension, the cardiovascular system changes to adapt to the varying neuro-humoral and hemodynamic changes and this may lead to the development of different left ventricular geometric patterns, each carrying a different risk profile for major adverse cardiovascular events. METHODS: Using a consecutive sampling technique, a cross-sectional, prospective, hospital based study was done and two hundred and twenty seven (227) hypertensive patients were studied. RESULTS: The distribution of different abnormal LV geometrical patterns was 19.8%, 28.2%, 22% for concentric remodelling, concentric hypertrophy and eccentric hypertrophy respectively. With echocardiographic criteria, the proportion of patients with left ventricular hypertrophy (LVH) was higher when left ventricular mass (LVM) was indexed to height(2.7) than to body surface area (70.0% vs. 52.9%). Duration of hypertension markedly influenced the type of LV geometry with normal LV geometry predominating in early hypertension and abnormal geometrical patterns predominating in late hypertension. The left ventricular fractional shortening decreased with duration of hypertension and was common in patients with eccentric hypertrophy. Age of the patient, systolic blood pressure, duration of hypertension and body mass index were found to be independent predictors left ventricular hypertrophy. CONCLUSION: About 70% of hypertensive patients had abnormal geometry existing in different patterns. Eccentric hypertrophy had more of clinical and echocardiographic features suggestive of reduced left ventricular systolic function. Hypertensive patients should be recognized as a heterogeneous population and therefore stratifying them into their respective LV geometrical patterns is useful as way of assessing their risk profile as well as instituting appropriate management.

Chromosome 1p21.3 microdeletions comprising DPYD and MIR137 are associated with intellectual disability.

BACKGROUND: MicroRNAs (miRNAs) are non-coding gene transcripts involved in post-transcriptional regulation of genes. Recent studies identified miRNAs as important regulators of learning and memory in model organisms. So far, no mutations in specific miRNA genes have been associated with impaired cognitive functions. METHODS AND RESULTS: In three sibs and two unrelated patients with intellectual disability (ID), overlapping 1p21.3 deletions were detected by genome-wide array analysis. The shortest region of overlap included dihydropyrimidine dehydrogenase (DPYD) and microRNA 137 (MIR137). DPYD is involved in autosomal recessive dihydropyrimidine dehydrogenase deficiency. Hemizygous DPYD deletions were previously suggested to contribute to a phenotype with autism spectrum disorder and speech delay. Interestingly, the mature microRNA transcript microRNA-137 (miR-137) was recently shown to be involved in modulating neurogenesis in adult murine neuronal stem cells. Therefore, this study investigated the possible involvement of MIR137 in the 1p21.3-deletion phenotype. The patients displayed a significantly decreased expression of both precursor and mature miR-137 levels, as well as significantly increased expression of the validated downstream targets microphthalmia-associated transcription factor (MITF) and Enhancer of Zeste, Drosophila, Homologue 2 (EZH2), and the newly identified target Kruppel-like factor 4 (KLF4). The study also demonstrated significant enrichment of miR-137 at the synapses of cortical and hippocampal neurons, suggesting a role of miR-137 in regulating local synaptic protein synthesis machinery. CONCLUSIONS: This study showed that dosage effects of MIR137 are associated with 1p21.3 microdeletions and may therefore contribute to the ID phenotype in patients with deletions harbouring this miRNA. A local effect at the synapse might be responsible.

Early Onset Marfan Syndrome with multivalvular insufficiency: Report from a tertiary hospital in Tanzania, and a review of the recurrent c.7606G>A p.0 variant in FBN1.

Marfan Syndrome is an autosomal dominant connective tissue disorder caused by mutations in the FBN1 gene. Early Onset Marfan Syndrome is at the severe end of the Marfan syndrome spectrum and is frequently associated with variants in exons 24-32 of the FBN1 gene. To the best of our knowledge, this is the first molecularly confirmed patient from Sub-Saharan Africa with Early Onset Marfan Syndrome who presented with tall stature, arachnodactyly, multivalvular insufficiency and ectopia lentis. Sequencing analysis of FBN1 gene revealed a pathogenic (class 5) heterozygous recurrent variant in exon 61 (c.7606G > A p.0NM_000138.3), which was up to now not associated with rapidly progressive Marfan syndrome with multivalvular insufficiency and congestive cardiac failure. This further supports the notion that the interplay of the given FBN1 mutation, one or more genetic modifiers and epigenetic and environmental factors defines the disease phenotype.

Further molecular and clinical delineation of the Wisconsin syndrome phenotype associated with interstitial 3q24q25 deletions.

Deletions of the distal 3q22.3 region encompassing the gene forkhead transcription factor FOXL2 (FOXL2) usually result in intellectual disability (ID) and the highly recognizable blepharophimosis-ptosis-epicanthus inversus syndrome (BPES). We encountered three patients with molecularly defined interstitial deletions distal to the FOXL2 gene. They present with remarkably similar manifestations comprising variable ID, a coarse facial appearance, including prominent nose and eyebrows, hypogonadism and skin pigmentation abnormalities, and they share an approximately 8.8 Mb overlapping 3q24q25 deletion. Interestingly, one of the present patients was described previously in a clinical report with emphasis on her clinical similarity to the Wisconsin syndrome, suggesting that Wisconsin syndrome might be caused by a (micro) deletion within the 3q24q25 region.

Genotype-phenotype correlations in L1 syndrome: a guide for genetic counselling and mutation analysis.

OBJECTIVES: To develop a comprehensive mutation analysis system with a high rate of detection, to develop a tool to predict the chance of detecting a mutation in the L1CAM gene, and to look for genotype-phenotype correlations in the X-linked recessive disorder, L1 syndrome. METHODS: DNA from 367 referred patients was analysed for mutations in the coding sequences of the gene. A subgroup of 100 patients was also investigated for mutations in regulatory sequences and for large duplications. Clinical data for 106 patients were collected and used for statistical analysis. RESULTS: 68 different mutations were detected in 73 patients. In patients with three or more clinical characteristics of L1 syndrome, the mutation detection rate was 66% compared with 16% in patients with fewer characteristics. The detection rate was 51% in families with more than one affected relative, and 18% in families with one affected male. A combination of these two factors resulted in an 85% detection rate (OR 10.4, 95% CI 3.6 to 30.1). The type of mutation affects the severity of L1 syndrome. Children with a truncating mutation were more likely to die before the age of 3 than those with a missense mutation (52% vs 8%; p=0.02). CONCLUSIONS: We developed a comprehensive mutation detection system with a detection rate of almost 20% in unselected patients and up to 85% in a selected group. Using the patients' clinical characteristics and family history, clinicians can accurately predict the chance of finding a mutation. A genotype-phenotype correlation was confirmed. The occurrence of (maternal) germline mosaicism was proven.

A Longitudinal Comparison of Environmental Sound Recognition in Adults With Hearing Aids Before and After Cochlear Implantation.

Purpose The aims of this study were (a) to longitudinally assess environmental sound recognition (ESR) before and after cochlear implantation in a sample of postlingually deafened adults and (b) to assess the extent to which spectro-temporal processing abilities influence ESR with cochlear implants (CIs). Method In a longitudinal cohort study, 20 postlingually deafened adults were tested with hearing aids on the Familiar Environmental Sound Test-Identification and AzBio sentences in quiet pre-CI and 6 months post-CI. A subset of 11 participants were also tested 12 months post-CI. Pre-CI spectro-temporal processing was assessed using the Spectral-temporally Modulated Ripple Test. Results Average ESR accuracy pre-CI (M = 63.60%) was not significantly different from ESR accuracy at 6 months (M = 65.40%) or 12 months (M = 69.09%) post-CI. In 11 participants (55%), however, ESR improved following implantation by 10.91 percentage points, on average. Pre-CI ESR correlated moderately and significantly with pre-CI and 12-month post-CI AzBio scores, with a trend toward significance for AzBio performance at 6 months. Pre-CI spectro-temporal processing was moderately associated with ESR at 6 and 12 months post-CI but not with speech recognition post-CI. Conclusions The present findings failed to demonstrate an overall significant improvement in ESR following implantation. Nevertheless, more than half of our sample showed some degree of improvement in ESR. Several environmental sounds were poorly identified both before and after implantation. Spectro-temporal processing ability prior to implantation appears to predict postimplantation performance for ESR. These findings indicate the need for greater attention to ESR following cochlear implantation and for developing individualized targets for ESR rehabilitation. Supplemental Material https://doi.org/10.23641/asha.13876745.

The clinical spectrum of missense mutations of the first aspartic acid of cbEGF-like domains in fibrillin-1 including a recessive family.

Marfan syndrome (MFS) is a dominant disorder with a recognizable phenotype. In most patients with the classical phenotype mutations are found in the fibrillin-1 gene (FBN1) on chromosome 15q21. It is thought that most mutations act in a dominant negative way or through haploinsufficiency. In 9 index cases referred for MFS we detected heterozygous missense mutations in FBN1 predicted to substitute the first aspartic acid of different calcium-binding Epidermal Growth Factor-like (cbEGF) fibrillin-1 domains. A similar mutation was found in homozygous state in 3 cases in a large consanguineous family. Heterozygous carriers of this mutation had no major skeletal, cardiovascular or ophthalmological features of MFS. In the literature 14 other heterozygous missense mutations are described leading to the substitution of the first aspartic acid of a cbEGF domain and resulting in a Marfan phenotype. Our data show that the phenotypic effect of aspartic acid substitutions in the first position of a cbEGF domain can range from asymptomatic to a severe neonatal phenotype. The recessive nature with reduced expression of FBN1 in one of the families suggests a threshold model combined with a mild functional defect of this specific mutation.