Gülen Eda Utine

KIF7 mutations cause fetal hydrolethalus and acrocallosal syndromes

KIF7, the human ortholog of Drosophila Costal2, is a key component of the Hedgehog signaling pathway. Here we report mutations in KIF7 in individuals with hydrolethalus and acrocallosal syndromes, two multiple malformation disorders with overlapping features that include polydactyly, brain abnormalities and cleft palate. Consistent with a role of KIF7 in Hedgehog signaling, we show deregulation of most GLI transcription factor targets and impaired GLI3 processing in tissues from individuals with KIF7 mutations. KIF7 is also a likely contributor of alleles across the ciliopathy spectrum, as sequencing of a diverse cohort identified several missense mutations detrimental to protein function. In addition, in vivo genetic interaction studies indicated that knockdown of KIF7 could exacerbate the phenotype induced by knockdown of other ciliopathy transcripts. Our data show the role of KIF7 in human primary cilia, especially in the Hedgehog pathway through the regulation of GLI targets, and expand the clinical spectrum of ciliopathies.

Haploinsufficiency of a Spliceosomal GTPase Encoded by EFTUD2 Causes Mandibulofacial Dysostosis with Microcephaly

Mandibulofacial dysostosis with microcephaly (MFDM) is a rare sporadic syndrome comprising craniofacial malformations, microcephaly, developmental delay, and a recognizable dysmorphic appearance. Major sequelae, including choanal atresia, sensorineural hearing loss, and cleft palate, each occur in a significant proportion of affected individuals. We present detailed clinical findings in 12 unrelated individuals with MFDM; these 12 individuals compose the largest reported cohort to date. To define the etiology of MFDM, we employed whole-exome sequencing of four unrelated affected individuals and identified heterozygous mutations or deletions of EFTUD2 in all four. Validation studies of eight additional individuals with MFDM demonstrated causative EFTUD2 mutations in all affected individuals tested. A range of EFTUD2-mutation types, including null alleles and frameshifts, is seen in MFDM, consistent with haploinsufficiency; segregation is de novo in all cases assessed to date. U5-116kD, the protein encoded by EFTUD2, is a highly conserved spliceosomal GTPase with a central regulatory role in catalytic splicing and post-splicing-complex disassembly. MFDM is the first multiple-malformation syndrome attributed to a defect of the major spliceosome. Our findings significantly extend the range of reported spliceosomal phenotypes in humans and pave the way for further investigation in related conditions such as Treacher Collins syndrome.

Exome sequencing unravels unexpected differential diagnoses in individuals with the tentative diagnosis of Coffin–Siris and Nicolaides–Baraitser syndromes

Coffin–Siris syndrome (CSS) and Nicolaides–Baraitser syndrome (NCBRS) are rare intellectual disability/congenital malformation syndromes that represent distinct entities but show considerable clinical overlap. They are caused by mutations in genes encoding members of the BRG1- and BRM-associated factor (BAF) complex. However, there are a number of patients with the clinical diagnosis of CSS or NCBRS in whom the causative mutation has not been identified. In this study, we performed trio-based whole-exome sequencing (WES) in ten previously described but unsolved individuals with the tentative diagnosis of CSS or NCBRS and found causative mutations in nine out of ten individuals. Interestingly, our WES analysis disclosed overlapping differential diagnoses including Wiedemann–Steiner, Kabuki, and Adams–Oliver syndromes. In addition, most likely causative de novo mutations were identified in GRIN2A and SHANK3. Moreover, trio-based WES detected SMARCA2 and SMARCA4 deletions, which had not been annotated in a previous Haloplex target enrichment and next-generation sequencing of known CSS/NCBRS genes emphasizing the advantages of WES as a diagnostic tool. In summary, we discuss the phenotypic and diagnostic challenges in clinical genetics, establish important differential diagnoses, and emphasize the cardinal features and the broad clinical spectrum of BAF complex disorders and other disorders caused by mutations in epigenetic landscapers.

A newborn with overlapping features of AEC and EEC syndromes

Ectrodactyly, ectodermal dysplasia, clefting (EEC) syndrome is the prototype of several p63 conditions, which include ankyloblepharon, ectodermal dysplasia, clefting (AEC) syndrome, limb‐mammary syndrome (LMS), Rapp‐Hodgkin syndrome (RHS), ADULT syndrome, and others. All these disorders include combinations of ectodermal dysplasia, orofacial clefting and limb malformations in variable severity. A newborn patient is presented with diffuse erythematous and desquamating skin lesions and anal atresia. She also had sparse and lightly colored thin hair, deeply set eyes, hypoplastic alae nasi, and a short philtrum. Cleft lip/palate and ankyloblepharon were not present. Complete cutaneous syndactyly was present on both hands in between the third and fourth fingers. Mild ectrodactyly was evident on all four extremities in between first and second digits. There was post‐axial polydactyly on both feet. Anal atresia was present and defecation occurred through a rectovaginal fistula. The patient represented an interesting overlapping clinical condition between AEC and EEC syndromes. Diffuse skin lesions with excoriation and desquamation suggest AEC syndrome, despite the absence of ankyloblepharon, however; ectrodactyly and polydactyly strongly suggest the EEC syndrome. C308Y mutation in exon 8 of TP63 gene was detected, which was previously described to lead only to EEC syndrome and not to any of the other allelic conditions. These data emphasize the large degree of clinical variability that may be seen for specific TP63 mutations.

Bi-allelic Mutations in KLHL7 Cause a Crisponi/CISS1-like Phenotype Associated with Early-Onset Retinitis Pigmentosa

Crisponi syndrome (CS)/cold-induced sweating syndrome type 1 (CISS1) is a very rare autosomal-recessive disorder characterized by a complex phenotype with high neonatal lethality, associated with the following main clinical features: hyperthermia and feeding difficulties in the neonatal period, scoliosis, and paradoxical sweating induced by cold since early childhood. CS/CISS1 can be caused by mutations in cytokine receptor-like factor 1 (CRLF1). However, the physiopathological role of CRLF1 is still poorly understood. A subset of CS/CISS1 cases remain yet genetically unexplained after CRLF1 sequencing. In five of them, exome sequencing and targeted Sanger sequencing identified four homozygous disease-causing mutations in kelch-like family member 7 (KLHL7), affecting the Kelch domains of the protein. KLHL7 encodes a BTB-Kelch-related protein involved in the ubiquitination of target proteins for proteasome-mediated degradation. Mono-allelic substitutions in other domains of KLHL7 have been reported in three families affected by a late-onset form of autosomal-dominant retinitis pigmentosa. Retinitis pigmentosa was also present in two surviving children reported here carrying bi-allelic KLHL7 mutations. KLHL7 mutations are thus associated with a more severe phenotype in recessive than in dominant cases. Although these data further support the pathogenic role of KLHL7 mutations in a CS/CISS1-like phenotype, they do not explain all their clinical manifestations and highlight the high phenotypic heterogeneity associated with mutations in KLHL7.

A novel mutation in RNU4ATAC in a patient with microcephalic osteodysplastic primordial dwarfism type I.

A Novel Mutation in RNU4ATAC in a Patient with Microcephalic Osteodysplastic Primordial Dwarfism Type I Esra Kilic,* Gökhan Yigit, Gülen Eda Utine, Bernd Wollnik, Ercan Mihci, Banu Güzel Nur, and Koray Boduroglu Faculty of Medicine, Division of Pediatric Genetics, Hacettepe University, Ankara, Turkey Institute of Human Genetics, University of Cologne, Cologne, Germany Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany Faculty of Medicine, Division of Pediatric Genetics, Akdeniz University, Antalya, Turkey

Homozygosity for a novel truncating mutation confirms TBX15 deficiency as the cause of Cousin syndrome

Cousin syndrome, also called pelviscapular dysplasia (OMIM 260660), is characterized by short stature, craniofacial dysmorphism, and multiple skeletal anomalies. Following its description in two sibs in 1982, no new cases have been observed until the observation of two unrelated cases in 2008 who were homozygous for frameshift mutations in TBX15. We investigated an adult individual with short stature, a complex craniofacial dysmorphism, malformed and rotated ears, short neck, elbow contractures, hypoacusis, and hypoplasia of scapula and pelvis on radiographs. We identified homozygosity for a novel nonsense mutation (c.841C>T) in TBX15 predicted to cause a premature stop (p.Arg281*) with truncation of the protein. This observation confirms that Cousin syndrome is a consistent and clinically recognizable phenotype caused by loss of function of TBX15.

Positive effects of an angiotensin II type 1 receptor antagonist in Camurati-Engelmann disease: a single case observation.

Camurati–Engelmann disease is characterized by hyperostosis of the long bones and the skull, muscle atrophy, severe limb pain, and progressive joint contractures in some patients. It is caused by heterozygous mutations in the transforming growth factor β1 (TGFβ1) believed to result in improper folding of the latency‐associated peptide domain of TGFβ1 and thus in increased or deregulated bioactivity. Losartan, an angiotensin II type 1 receptor antagonist, has been found to downregulate the expression of TGFβ type 1 and 2 receptors. Clinical trials with losartan have shown a benefit in Marfan syndrome, while trials are underway for Duchenne muscular dystrophy and other myopathies associated with TGFβ1 signaling. We hypothesized that due to its anti‐TGFβ1 activity, losartan might be beneficial in Camurati–Engelmann disease. This report concerns a boy who presented at age 13 years with severe limb pain and difficulty in walking. Clinical and radiographic evaluation results were compatible with Camurati–Engelmann disease and the diagnosis was confirmed by mutation analysis (c.652C > T [p.Arg218Cys]). The boy underwent an experimental treatment with losartan at a dosage of 50 mg/day, orally. During the treatment period of 18 months, the intensity and frequency of limb pain decreased significantly (as shown by a pain diary), and muscle strength improved, allowing the boy to resume walking and climbing stairs. No obvious side effects were observed. We cautiously conclude that TGFβ1 inhibition with losartan deserves further evaluation in the clinical management of Camurati–Engelmann disease.

Catel–Manzke syndrome: A clinical report suggesting autosomal recessive inheritance†

We describe a 3‐month‐old male infant with cleft palate, glossoptosis, micrognathia, and bilateral clinodactyly, an association which is characteristic of Catel–Manzke syndrome. In addition, the patient had ligamentous laxity in the knee which is a rare finding of this syndrome. The mode of inheritance of Catel–Manzke syndrome is unknown. Most cases are thought to be sporadic but the present patient with consanguinity between the parents and a possibly affected sib provide support for autosomal recessive inheritance.

Unilateral Petersʼ anomaly in an infant with 22q11.2 deletion syndrome

The 22q11.2 deletion syndrome (Di George/velocardiofacial syndrome) is the most common microdeletion syndrome. The range of clinical features in affected individuals is extensive, including cardiac malformations, cleft palate or velopharyngeal insufficiency, developmental delay and mild facial dysmorphism. Here we present a 4-month-old boy, referred for facial dysmorphic findings. Peters’ anomaly in 22q11.2 deletion syndrome has been reported only once by Casteels and Devriendt (2005). Ours is the second case of the 22q11.2 microdeletion syndrome in association with Peters’ anomaly in the literature.