Phenotypic spectrum associated with PTCHD1 deletions and truncating mutations includes intellectual disability and autism spectrum disorder Ayeshah Chaudhry1, Abdul Noor2,3, Bryan Degagne3, Kate Baker4,21, Levinus A. Bok5, Angela F. Brady6, David Chitayat1,7, Brian Chung Hon-Yin8, Cheryl Cytrynbaum1,32, David Dyment9, Isabel Filges10, Benjamin Helm11, H. Terry Hutchison12, Linda Jo Bone Jeng13, Frederic Laumonnier14, Christian R. Marshall15, Moritz Menzel16, Sandhya Parkash17,18, Michael J. Parker19, The DDD Study20, F. Lucy Raymond 4,21, Andrea L. Rideout17, Wendy Roberts22, Rosemarie Rupps23, Ina Schanze24, Constance T.R.M. Schrander-Stumpel25, Marsha D. Speevak26, Dimitri J. Stavropoulos2,15, Servi J.C. Stevens25, Ellen R.A. Thomas27, Annick Toutain14,28, Samantha Vergano11, Rosanna Weksberg1,31,32, Stephen W. Scherer15,29,31, John B. Vincent3,30,31, Melissa T. Carter1,22 1
Department of Pediatrics, Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, University of Toronto, Toronto ON Canada 2 Department of Pathology and Laboratory Medicine, The Hospital for Sick Children, Toronto ON Canada 3 Molecular Neuropsychiatry & Development Lab, Campbell Family Mental Health Research Institute, The Centre for Addiction & Mental Health, Toronto ON Canada 4 Department of Medical Genetics, University of Cambridge, Cambridge, United Kingdom 5 Department of Clinical Genetics, Unit of Cytogenetics, Maastricht University Medical Center, Maastricht, the Netherlands 6 North West Thames Regional Genetics Service, Northwick Park Hospital, Harrow, United Kingdom 7 The Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and Gynecology, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada 8 Department of Pediatrics and Adolescent Medicine, Department of Obstetrics and Gynaecology, Centre for Reproduction, Development and Growth, Centre for Genomic Sciences, The University of Hong Kong, Hong Kong 9 Department of Genetics, Children’s Hospital of Eastern Ontario, Ottawa ON Canada 10 Division of Medical Genetics, Department of Biomedicine, University Hospital Basel, Basel, Switzerland 11 Division of Medical Genetics and Metabolism, Children's Hospital of The King's Daughters/Eastern Virginia Medical School, Norfolk, VA, USA 12 Departments of Neurology and Pediatrics, UCSF Fresno Medical Education Program, University of California, San Francisco, USA 13 Department of Laboratory Medicine, University of California, San Francisco, USA 14 UMR_INSERM U930 Faculté de Médecine, Université François Rabelais, Tours, France 15 The Centre for Applied Genomics, The Hospital for Sick Children, Toronto ON Canada 16 CeGaT GmbH, Tuebingen, Germany 17 Maritime Medical Genetics Service, IWK Health Centre, Halifax, NS Canada 18 Dalhousie University Halifax, NS Canada 19 Sheffield Clinical Genetics Service, Sheffield Children's Hospital, Western Bank, Sheffield, United Kingdom 20 Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1HH, United Kingdom 21 Institute for Medical Research Wellcome Trust, University of Cambridge, Cambridge, United Kingdom 22 Autism Research Unit, The Hospital for Sick Children, Toronto ON Canada 23 Department of Medical Genetics, Children’s and Women’s Health Centre, University of British Columbia, Vancouver BC Canada 24 Institute of Human Genetics, University Hospital Magedeburg, Germany 25 Department of Clinical Genetics and School for Oncology & Developmental Biology (GROW), Maastricht UMC+, Maastricht, the Netherlands 26 Credit Valley Site, Trillium Health Partners, Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto ON Canada 27 Clinical Genetics Department, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom 28 Service de Génétique, Centre Hospitalo-Universitaire, Tours, France 29 McLaughlin Centre and Department of Molecular Genetics, University of Toronto, Toronto ON Canada 30 Department of Psychiatry, University of Toronto, Toronto ON Canada 31 Institute of Medical Science, University of Toronto, Toronto ON Canada 32 Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
Corresponding Authors: Melissa Carter, M.D. Division of Clinical and Metabolic Genetics This article is protected by copyright. All rights reserved
The Hospital for Sick Children 555 University Avenue Toronto, ON, Canada M5G 1X8 Phone: (416) 813-5340 Fax: (416) 813-5345 Email: [email protected] John B. Vincent, Ph.D. Neurogenetics Section, Campbell Family Mental Health Research Institute Centre for Addiction and Mental Health (CAMH) R-32, 250 College Street, Toronto, ON, Canada M5T 1R8 Email: [email protected]
CONFLICT OF INTEREST STATEMENT JBV and SWS hold a U.S. patent for molecular diagnostics for PTCHD1, and Centre for Addiction & Mental Health and Hospital for Sick Children derive revenue from licensing and royalties of molecular diagnostic testing. The other authors declare no conflict of interest.
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/cge.12482
This article is protected by copyright. All rights reserved
ACKNOWLEDGEMENTS The authors wish to thank the families who participated in this study. This work was supported by grants from Genome Canada and the Ontario Genomics Institute (SWS) and Canadian Institutes of Health Research grant MOP-114592 (JBV). SWS is supported by the GlaxoSmithKline-CIHR Endowed Chair in Genome Sciences at The Hospital for Sick Children and University of Toronto. FL and AT received funding from European Union (FP7 Gencodys project n°241995) and from Fondation de France. The DDD study presents independent research commissioned by the Health Innovation Challenge Fund [grant number HICF-1009-003], a parallel funding partnership between the Wellcome Trust and the Department of Health, and the Wellcome Trust Sanger Institute [grant number WT098051]. The views expressed in this publication are those of the authors and not necessarily those of the Wellcome Trust or the Department of Health. The study has UK Research Ethics Committee approval (10/H0305/83, granted by the Cambridge South REC, and GEN/284/12 granted by the Republic of Ireland REC). The research team acknowledges the support of the National Institute for Health Research, through the Comprehensive Clinical Research Network. This study makes use of data generated by the DECIPHER and ISCA (www.iscaconsortium.org) consortia. A full list of centers contributing to the generation of the DECIPHER data is available from http://decipher.sanger.ac.uk and via email from [email protected]. Funding for the DECIPHER project was provided by the Wellcome Trust. ABSTRACT Studies of genomic copy number variants (CNVs) have identified genes associated with autism spectrum disorder (ASD) and intellectual disability (ID) such as NRXN1, SHANK2, SHANK3 and PTCHD1. Deletions have been reported in PTCHD1 however there has been little information available regarding the clinical presentation of these individuals. Herein we present 23 individuals with PTCHD1 deletions or truncating mutations with detailed phenotypic descriptions. The results suggest that individuals with disruption of the PTCHD1 coding region may have subtle dysmorphic features including a long face, prominent forehead, puffy eyelids and a thin upper lip. They do not have a consistent pattern of associated congenital anomalies or growth abnormalities. They have mild to moderate global developmental delay, variable degrees of ID, and many have prominent behavioural issues. Over 40 percent of subjects have ASD or ASD-like behaviours. The only consistent neurological findings in our cohort are orofacial hypotonia and mild motor incoordination. Our findings suggest that hemizygous PTCHD1 loss of function causes an X-linked neurodevelopmental disorder with a strong propensity to autistic behaviours. Detailed neuropsychological studies are needed to better define the cognitive and behavioural phenotype. This article is protected by copyright. All rights reserved
KEY WORDS Autism spectrum disorder/ intellectual disability/ PTCHD1/ phenotype/ X-linked
INTRODUCTION Disruptions of the X-linked PTCHD1 gene were first implicated in autism spectrum disorder (ASD) in a genome-wide CNV screening study of 427 unrelated individuals with ASDs [1]. A deletion encompassing exon 1 of the PTCHD1 gene was found in dizygotic twin boys, and not in 500 control males. In a follow-up study, two additional deletions were identified in one male with ASD and in a family with ID in two brothers and their maternal uncle [2, 3]. These deletions were identified only in males and were maternally inherited. Further genetic analysis of 996 families revealed missense variants in individuals affected with ASD and ID [2]. In addition, deletions in males with ASD in the region distal to and upstream of PTCHD1 were observed [4]. The combined data suggested that mutations in PTCHD1 and possibly deletions in the upstream regulatory region contribute to ASD and ID in ~1% of those studied. PTCHD1 maps to Xp22.11. In humans it is expressed in the brain, notably the cerebellum, as well as in other tissues. In mouse there is widespread expression in the developing and adult brain, with highest density in the cerebellum [2]. The PTCHD1 protein predominantly localizes to the cell membrane, and may function in the Hedgehog signaling pathway [2]. The phenotypic spectrum associated with deletions and mutations of PTCHD1 has not been fully elucidated. A single clinical report did describe two brothers with ID who had a deletion of the entire PTCHD1 gene [5]. The 6-year-old proband was described as nondysmorphic with global developmental delay, autistic traits, transient ataxic movements, hypotonia, and mild cerebral atrophy on brain imaging. His 20-year-old brother had a similar clinical course without autistic features [5]. We report the phenotype information of 23 individuals (22 males and one female) from 16 families with PTCHD1 exonic deletions or truncating mutations. Our findings support PTCHD1 gene disruptions as causing an X-linked non-syndromic neurodevelopmental disorder characterized by infantile hypotonia and motor incoordination, with variable features of intellectual disability, autism spectrum disorder, and other behavioural manifestations. We find no evidence for a recognizable pattern of congenital anomalies or serious medical comorbidities in association with disruptions/deletions of this gene.
This article is protected by copyright. All rights reserved
MATERIALS AND METHODS Human subjects Twenty-three individuals from 16 families with a deletion or truncating mutation of PTCHD1 were included. Four of these families have been previously reported in the literature [1-5]. Clinical information and the genomic coordinates of the deletions were obtained from the respective physicians by way of structured clinical questionnaire. Details of microarray platforms used for the copy number analysis and the genomic coordinates for each patient can be found in the supplementary information. Where permission was granted by the family, we obtained photographs of each subject for documentation of dysmorphic features.
RESULTS The 23 subjects ranged in age from 15 months to 44 years at the time of last assessment. A summary of clinical features of study subjects is found in Table 1. All but one of our subjects was male. The only female patient in our cohort was a 5-year-old girl with isolated speech delay and a formal diagnosis of ASD. Eighteen subjects have a deletion encompassing coding regions of PTCHD1. Deletion size ranged from 46 to 963 Kb (Fig. 1). In three families, probands (as well as an affected maternal uncle in two families) were found to have a truncating mutation of PTCHD1. Two individuals (L1 and M1) had additional CNVs reported on clinical microarray: a 1.1 Mb duplication at 16p13.11 (chr16: 15,417,030-16,529,801; hg19) for L1, and a 654 Kb deletion at 1q21.2 (chr1: 147,986,516-148,640,398; hg19) for M1. The deletion or truncating mutation was maternally inherited in all but one individual where the mother was available for testing (94.4%); a deletion was de novo in one subject (J1). The mothers in six families (B, C, F, G, K and O) were tested for skewed X-inactivation. The mother in Family G had skewed X-inactivation (94:6). The X-inactivation pattern was random in the remaining mothers, with the exception of the mother in Family K, for whom X-inactivation studies were not informative. No significant growth abnormalities were found in the majority of our patients. Two (F3 and J1) reportedly had early failure to thrive (9%). Four (18%) were reported to have relative or absolute macrocephaly. Three (13%) had absolute or relative microcephaly. Although subtle dysmorphic features were reported in several subjects, most were described as non-dysmorphic (Fig. 2). The most commonly observed facial feature, in 11/23 (52%), was an open-mouth posture, likely secondary to orofacial hypotonia. This was generally more prominent in the younger children. Some of the older individuals tended to have a long, narrow face with small chin and prominent upper central incisors. Other common features included a tall forehead, puffy eyelids, a depressed and narrow nasal bridge with a broad This article is protected by copyright. All rights reserved
nasal tip and anteverted nostrils, and a thin upper vermillion border of the lip. L1 and F3 were noted to have more striking facial features as compared to other individuals. Congenital anomalies were found in two subjects: C2 had craniosynostosis of the metopic suture requiring surgery, and N1 had bilateral 2-3 toe syndactyly (also present in his father and two siblings, none of whom had a PTCHD1 disruption). Eighteen (78%) subjects were reported to have global developmental delay (GDD) in early childhood. One subject (I1) had isolated motor delay at the last assessment at 15 months. M1 had fine motor and speech delays only, while the female subject (K1) had isolated speech delay. Nine (39%) subjects have been formally diagnosed with ID, ranging from mild to severe. G1 and G2, 13-year-old dizygotic twin brothers, have IQs within the normal range, but struggle with academics due, at least in part, to formally-diagnosed language-based learning disability. Similarly, subject N1 also has been diagnosed with learning disability. Five subjects are still too young to have a formal IQ assessment, and two (A2 and P1) have not been tested. Fifteen (65%) individuals had behavioral and/or psychiatric diagnoses including autism (Table 1). Eight subjects (35%) had a formal diagnosis of ASD. Additionally, C1 and J1 had “ASD features” noted, but had not yet been formally assessed. Other behavioural issues reported in our subjects included vocal and motor tics, anxiety, attention deficit and/or hyperactivity, impulsivity, aggressive behaviours and sleep disorder. Subtle neurological findings were reported in 15 (65%) of our subjects. Generalized hypotonia was found in six (26%), while mild peripheral hypertonia was reported in two (9%). The rest were reported to have normal muscle tone at the time of last assessment. None had seizures aside from F1, who had adult-onset seizures reportedly in association with excessive alcohol intake. Five subjects (21.7%) had a broad-based gait and/or poor balance, which improved with age. Brain imaging had been performed on 9 subjects (eight with MRI and one with CT); all scans were reportedly normal except B1 who had mild cerebral atrophy on MRI scan at 3.5 years of age. Three of our subjects had at least one EEG, and all were reportedly normal. Medical co-morbidities were uncommon in our subjects. Eight (34.8%) were reported to have a variety of mild vision problems including strabismus (F3, G2 and I1), jerky oculomotor movements (C2), cataracts (F2), astigmatism and myopia (N1). One subject (J1) had mild conductive hearing loss secondary to recurrent middle ear infections. Musculoskeletal findings included kyphosis (G1 and G2), mild scoliosis (O1) and pes planus with small joint hypermobility (E1). Dermatologic findings included a single large café-au-lait macule over left scapula (E1), three café-au-lait spots in M1 (two 1.5 cm and one
Department of Pediatrics, Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, University of Toronto, Toronto ON Canada 2 Department of Pathology and Laboratory Medicine, The Hospital for Sick Children, Toronto ON Canada 3 Molecular Neuropsychiatry & Development Lab, Campbell Family Mental Health Research Institute, The Centre for Addiction & Mental Health, Toronto ON Canada 4 Department of Medical Genetics, University of Cambridge, Cambridge, United Kingdom 5 Department of Clinical Genetics, Unit of Cytogenetics, Maastricht University Medical Center, Maastricht, the Netherlands 6 North West Thames Regional Genetics Service, Northwick Park Hospital, Harrow, United Kingdom 7 The Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and Gynecology, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada 8 Department of Pediatrics and Adolescent Medicine, Department of Obstetrics and Gynaecology, Centre for Reproduction, Development and Growth, Centre for Genomic Sciences, The University of Hong Kong, Hong Kong 9 Department of Genetics, Children’s Hospital of Eastern Ontario, Ottawa ON Canada 10 Division of Medical Genetics, Department of Biomedicine, University Hospital Basel, Basel, Switzerland 11 Division of Medical Genetics and Metabolism, Children's Hospital of The King's Daughters/Eastern Virginia Medical School, Norfolk, VA, USA 12 Departments of Neurology and Pediatrics, UCSF Fresno Medical Education Program, University of California, San Francisco, USA 13 Department of Laboratory Medicine, University of California, San Francisco, USA 14 UMR_INSERM U930 Faculté de Médecine, Université François Rabelais, Tours, France 15 The Centre for Applied Genomics, The Hospital for Sick Children, Toronto ON Canada 16 CeGaT GmbH, Tuebingen, Germany 17 Maritime Medical Genetics Service, IWK Health Centre, Halifax, NS Canada 18 Dalhousie University Halifax, NS Canada 19 Sheffield Clinical Genetics Service, Sheffield Children's Hospital, Western Bank, Sheffield, United Kingdom 20 Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1HH, United Kingdom 21 Institute for Medical Research Wellcome Trust, University of Cambridge, Cambridge, United Kingdom 22 Autism Research Unit, The Hospital for Sick Children, Toronto ON Canada 23 Department of Medical Genetics, Children’s and Women’s Health Centre, University of British Columbia, Vancouver BC Canada 24 Institute of Human Genetics, University Hospital Magedeburg, Germany 25 Department of Clinical Genetics and School for Oncology & Developmental Biology (GROW), Maastricht UMC+, Maastricht, the Netherlands 26 Credit Valley Site, Trillium Health Partners, Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto ON Canada 27 Clinical Genetics Department, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom 28 Service de Génétique, Centre Hospitalo-Universitaire, Tours, France 29 McLaughlin Centre and Department of Molecular Genetics, University of Toronto, Toronto ON Canada 30 Department of Psychiatry, University of Toronto, Toronto ON Canada 31 Institute of Medical Science, University of Toronto, Toronto ON Canada 32 Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
Corresponding Authors: Melissa Carter, M.D. Division of Clinical and Metabolic Genetics This article is protected by copyright. All rights reserved
The Hospital for Sick Children 555 University Avenue Toronto, ON, Canada M5G 1X8 Phone: (416) 813-5340 Fax: (416) 813-5345 Email: [email protected] John B. Vincent, Ph.D. Neurogenetics Section, Campbell Family Mental Health Research Institute Centre for Addiction and Mental Health (CAMH) R-32, 250 College Street, Toronto, ON, Canada M5T 1R8 Email: [email protected]
CONFLICT OF INTEREST STATEMENT JBV and SWS hold a U.S. patent for molecular diagnostics for PTCHD1, and Centre for Addiction & Mental Health and Hospital for Sick Children derive revenue from licensing and royalties of molecular diagnostic testing. The other authors declare no conflict of interest.
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/cge.12482
This article is protected by copyright. All rights reserved
ACKNOWLEDGEMENTS The authors wish to thank the families who participated in this study. This work was supported by grants from Genome Canada and the Ontario Genomics Institute (SWS) and Canadian Institutes of Health Research grant MOP-114592 (JBV). SWS is supported by the GlaxoSmithKline-CIHR Endowed Chair in Genome Sciences at The Hospital for Sick Children and University of Toronto. FL and AT received funding from European Union (FP7 Gencodys project n°241995) and from Fondation de France. The DDD study presents independent research commissioned by the Health Innovation Challenge Fund [grant number HICF-1009-003], a parallel funding partnership between the Wellcome Trust and the Department of Health, and the Wellcome Trust Sanger Institute [grant number WT098051]. The views expressed in this publication are those of the authors and not necessarily those of the Wellcome Trust or the Department of Health. The study has UK Research Ethics Committee approval (10/H0305/83, granted by the Cambridge South REC, and GEN/284/12 granted by the Republic of Ireland REC). The research team acknowledges the support of the National Institute for Health Research, through the Comprehensive Clinical Research Network. This study makes use of data generated by the DECIPHER and ISCA (www.iscaconsortium.org) consortia. A full list of centers contributing to the generation of the DECIPHER data is available from http://decipher.sanger.ac.uk and via email from [email protected]. Funding for the DECIPHER project was provided by the Wellcome Trust. ABSTRACT Studies of genomic copy number variants (CNVs) have identified genes associated with autism spectrum disorder (ASD) and intellectual disability (ID) such as NRXN1, SHANK2, SHANK3 and PTCHD1. Deletions have been reported in PTCHD1 however there has been little information available regarding the clinical presentation of these individuals. Herein we present 23 individuals with PTCHD1 deletions or truncating mutations with detailed phenotypic descriptions. The results suggest that individuals with disruption of the PTCHD1 coding region may have subtle dysmorphic features including a long face, prominent forehead, puffy eyelids and a thin upper lip. They do not have a consistent pattern of associated congenital anomalies or growth abnormalities. They have mild to moderate global developmental delay, variable degrees of ID, and many have prominent behavioural issues. Over 40 percent of subjects have ASD or ASD-like behaviours. The only consistent neurological findings in our cohort are orofacial hypotonia and mild motor incoordination. Our findings suggest that hemizygous PTCHD1 loss of function causes an X-linked neurodevelopmental disorder with a strong propensity to autistic behaviours. Detailed neuropsychological studies are needed to better define the cognitive and behavioural phenotype. This article is protected by copyright. All rights reserved
KEY WORDS Autism spectrum disorder/ intellectual disability/ PTCHD1/ phenotype/ X-linked
INTRODUCTION Disruptions of the X-linked PTCHD1 gene were first implicated in autism spectrum disorder (ASD) in a genome-wide CNV screening study of 427 unrelated individuals with ASDs [1]. A deletion encompassing exon 1 of the PTCHD1 gene was found in dizygotic twin boys, and not in 500 control males. In a follow-up study, two additional deletions were identified in one male with ASD and in a family with ID in two brothers and their maternal uncle [2, 3]. These deletions were identified only in males and were maternally inherited. Further genetic analysis of 996 families revealed missense variants in individuals affected with ASD and ID [2]. In addition, deletions in males with ASD in the region distal to and upstream of PTCHD1 were observed [4]. The combined data suggested that mutations in PTCHD1 and possibly deletions in the upstream regulatory region contribute to ASD and ID in ~1% of those studied. PTCHD1 maps to Xp22.11. In humans it is expressed in the brain, notably the cerebellum, as well as in other tissues. In mouse there is widespread expression in the developing and adult brain, with highest density in the cerebellum [2]. The PTCHD1 protein predominantly localizes to the cell membrane, and may function in the Hedgehog signaling pathway [2]. The phenotypic spectrum associated with deletions and mutations of PTCHD1 has not been fully elucidated. A single clinical report did describe two brothers with ID who had a deletion of the entire PTCHD1 gene [5]. The 6-year-old proband was described as nondysmorphic with global developmental delay, autistic traits, transient ataxic movements, hypotonia, and mild cerebral atrophy on brain imaging. His 20-year-old brother had a similar clinical course without autistic features [5]. We report the phenotype information of 23 individuals (22 males and one female) from 16 families with PTCHD1 exonic deletions or truncating mutations. Our findings support PTCHD1 gene disruptions as causing an X-linked non-syndromic neurodevelopmental disorder characterized by infantile hypotonia and motor incoordination, with variable features of intellectual disability, autism spectrum disorder, and other behavioural manifestations. We find no evidence for a recognizable pattern of congenital anomalies or serious medical comorbidities in association with disruptions/deletions of this gene.
This article is protected by copyright. All rights reserved
MATERIALS AND METHODS Human subjects Twenty-three individuals from 16 families with a deletion or truncating mutation of PTCHD1 were included. Four of these families have been previously reported in the literature [1-5]. Clinical information and the genomic coordinates of the deletions were obtained from the respective physicians by way of structured clinical questionnaire. Details of microarray platforms used for the copy number analysis and the genomic coordinates for each patient can be found in the supplementary information. Where permission was granted by the family, we obtained photographs of each subject for documentation of dysmorphic features.
RESULTS The 23 subjects ranged in age from 15 months to 44 years at the time of last assessment. A summary of clinical features of study subjects is found in Table 1. All but one of our subjects was male. The only female patient in our cohort was a 5-year-old girl with isolated speech delay and a formal diagnosis of ASD. Eighteen subjects have a deletion encompassing coding regions of PTCHD1. Deletion size ranged from 46 to 963 Kb (Fig. 1). In three families, probands (as well as an affected maternal uncle in two families) were found to have a truncating mutation of PTCHD1. Two individuals (L1 and M1) had additional CNVs reported on clinical microarray: a 1.1 Mb duplication at 16p13.11 (chr16: 15,417,030-16,529,801; hg19) for L1, and a 654 Kb deletion at 1q21.2 (chr1: 147,986,516-148,640,398; hg19) for M1. The deletion or truncating mutation was maternally inherited in all but one individual where the mother was available for testing (94.4%); a deletion was de novo in one subject (J1). The mothers in six families (B, C, F, G, K and O) were tested for skewed X-inactivation. The mother in Family G had skewed X-inactivation (94:6). The X-inactivation pattern was random in the remaining mothers, with the exception of the mother in Family K, for whom X-inactivation studies were not informative. No significant growth abnormalities were found in the majority of our patients. Two (F3 and J1) reportedly had early failure to thrive (9%). Four (18%) were reported to have relative or absolute macrocephaly. Three (13%) had absolute or relative microcephaly. Although subtle dysmorphic features were reported in several subjects, most were described as non-dysmorphic (Fig. 2). The most commonly observed facial feature, in 11/23 (52%), was an open-mouth posture, likely secondary to orofacial hypotonia. This was generally more prominent in the younger children. Some of the older individuals tended to have a long, narrow face with small chin and prominent upper central incisors. Other common features included a tall forehead, puffy eyelids, a depressed and narrow nasal bridge with a broad This article is protected by copyright. All rights reserved
nasal tip and anteverted nostrils, and a thin upper vermillion border of the lip. L1 and F3 were noted to have more striking facial features as compared to other individuals. Congenital anomalies were found in two subjects: C2 had craniosynostosis of the metopic suture requiring surgery, and N1 had bilateral 2-3 toe syndactyly (also present in his father and two siblings, none of whom had a PTCHD1 disruption). Eighteen (78%) subjects were reported to have global developmental delay (GDD) in early childhood. One subject (I1) had isolated motor delay at the last assessment at 15 months. M1 had fine motor and speech delays only, while the female subject (K1) had isolated speech delay. Nine (39%) subjects have been formally diagnosed with ID, ranging from mild to severe. G1 and G2, 13-year-old dizygotic twin brothers, have IQs within the normal range, but struggle with academics due, at least in part, to formally-diagnosed language-based learning disability. Similarly, subject N1 also has been diagnosed with learning disability. Five subjects are still too young to have a formal IQ assessment, and two (A2 and P1) have not been tested. Fifteen (65%) individuals had behavioral and/or psychiatric diagnoses including autism (Table 1). Eight subjects (35%) had a formal diagnosis of ASD. Additionally, C1 and J1 had “ASD features” noted, but had not yet been formally assessed. Other behavioural issues reported in our subjects included vocal and motor tics, anxiety, attention deficit and/or hyperactivity, impulsivity, aggressive behaviours and sleep disorder. Subtle neurological findings were reported in 15 (65%) of our subjects. Generalized hypotonia was found in six (26%), while mild peripheral hypertonia was reported in two (9%). The rest were reported to have normal muscle tone at the time of last assessment. None had seizures aside from F1, who had adult-onset seizures reportedly in association with excessive alcohol intake. Five subjects (21.7%) had a broad-based gait and/or poor balance, which improved with age. Brain imaging had been performed on 9 subjects (eight with MRI and one with CT); all scans were reportedly normal except B1 who had mild cerebral atrophy on MRI scan at 3.5 years of age. Three of our subjects had at least one EEG, and all were reportedly normal. Medical co-morbidities were uncommon in our subjects. Eight (34.8%) were reported to have a variety of mild vision problems including strabismus (F3, G2 and I1), jerky oculomotor movements (C2), cataracts (F2), astigmatism and myopia (N1). One subject (J1) had mild conductive hearing loss secondary to recurrent middle ear infections. Musculoskeletal findings included kyphosis (G1 and G2), mild scoliosis (O1) and pes planus with small joint hypermobility (E1). Dermatologic findings included a single large café-au-lait macule over left scapula (E1), three café-au-lait spots in M1 (two 1.5 cm and one
