Matthew Pastore

The prevalence of PTEN mutations in a clinical pediatric cohort with autism spectrum disorders, developmental delay, and macrocephaly

Purpose: To define the prevalence of PTEN mutations in a clinical cohort of pediatric subjects with autism spectrum disorders (ASDs), developmental delay/mental retardation (DD/MR), and/or macrocephaly and to assess genotype–phenotype correlations.Methods: Medical records of patients who had clinical PTEN gene sequencing ordered through our institution between January 1, 2005 and December 31, 2007 were abstracted to confirm genetic test results and medical diagnoses. Phenotypic information related to the diagnoses, prenatal history, early developmental milestones, physical characteristics, and family history for those with a confirmed PTEN mutation was also recorded.Results: One hundred fourteen patients were tested during this time period for indications of ASDs (N = 60), DD/MR (N = 49), or macrocephaly only (N = 5). Eleven mutations were identified: five in patients with ASDs and six in those with DD/MR, resulting in a prevalence of 8.3% and 12.2% in these respective clinical populations. All individuals with a PTEN mutation had significant macrocephaly (>2.0 SD)Conclusions: These data illustrate that PTEN gene sequencing has a high diagnostic yield when performed in a selected population of individuals with ASDs or DD/MR and macrocephaly. Germline mutations in PTEN are an important, identifiable etiology among these patients.

Confirmation study of PTEN mutations among individuals with autism or developmental delays/mental retardation and macrocephaly.

There is a strong genetic component to autism spectrum disorders (ASD), but due to significant genetic heterogeneity, individual genetic abnormalities contribute a small percentage to the overall total. Previous studies have demonstrated PTEN mutations in a sizable proportion of individuals with ASD or mental retardation/developmental delays (MR/DD) and macrocephaly that do not have features of Cowden or Bannayan–Riley–Ruvalcaba syndrome. This study was performed to confirm our previous results. We reviewed the charts of individuals who had PTEN clinical sequencing performed at our institution from January 2008 to July 2009. There were 93 subjects tested from our institution during that period. PTEN mutations were found in 2/39 (5.1%) ASD patients and 2/51 (3.9%) MR/DD patients. Three additional patients without mutations had no diagnostic information. Multiple relatives of individuals with a PTEN mutation had macrocephaly, MR, or early onset cancer (breast, renal, and prostate). Of those relatives tested, all had the familial PTEN mutation. None of the affected relatives had previously been diagnosed with Cowden or Bannayan–Riley–Ruvalcaba syndrome. We noted in our previous study several adult relatives without any findings who carried a mutation. Combined with data from our previous cohort, we have found PTEN mutations in 7/99 (7.1%) of individuals with ASD and 8/100 (8.0%) of individuals with MR/DD, all of whom had macrocephaly. We recommend testing for mutations in PTEN for individuals with ASD or MR/DD and macrocephaly. If mutations are found, other family members should be offered testing and the adults offered cancer screening if they have a PTEN mutation.

Increasing knowledge of PTEN germline mutations: Two additional patients with autism and macrocephaly

Recently, Butler et al. [2005; J Med Genet 42:318–321] reported the presence of heterozygous germline mutations in the PTEN tumor suppressor gene in three children with autism and macrocephaly. Here, we report the presence of PTEN mutations in two additional unrelated children with macrocephaly and autism. Our findings extend those of Butler et al. and suggest that PTEN gene sequencing should be included in the genetic evaluation of this subset of autistic individuals.

Genetic testing in autism: how much is enough?

Purpose: To evaluate the yield of genetic testing in children with autism spectrum disorders.Methods: We performed a retrospective chart review of 71 unrelated patients with a diagnosis of an isolated autism spectrum disorder seen in a genetics clinic over a period of 14 months. For most, referrals occurred after evaluation by a developmental pediatrician and/or psychologist to establish the diagnosis. Tiered laboratory testing for the majority of the patients followed a guideline that was developed in collaboration with clinicians at The Autism Center at Childrens Hospital, Columbus, OH.Results: The patients included 57 males and 14 females; 57 met DSM-IV criteria for autism, with the rest being Asperger or pervasive developmental disorder not otherwise specified. Macrocephaly [head circumference (HC) ≥95%] was present in 19 (27%). Two children had visible chromosome abnormalities (47,XYY; 48,XY + 2mar/49,XY + 3mar). Two patients with autism and macrocephaly had heterozygous mutations in the PTEN tumor suppressor gene. Three females had Rett syndrome, each confirmed by DNA sequencing of the MECP2 gene. Extensive metabolic testing produced no positive results, nor did fragile X DNA testing.Conclusion: The overall diagnostic yield was 10% (7/71). PTEN gene sequencing should be considered in any child with macrocephaly and autism or developmental delay. Metabolic screening may not be warranted in autism spectrum disorders without more specific indications or additional findings.

Coronary artery disease in a Werner syndrome‐like form of progeria characterized by low levels of progerin, a splice variant of lamin A

Classical Hutchinson–Gilford progeria syndrome (HGPS) is caused by LMNA mutations that generate an alternatively spliced form of lamin A, termed progerin. HGPS patients present in early childhood with atherosclerosis and striking features of accelerated aging. We report on two pedigrees of adult‐onset coronary artery disease with progeroid features, who were referred to our International Registry of Werner Syndrome (WS) because of clinical features consistent with the diagnosis. No mutations were identified in the WRN gene that is responsible for WS, among these patients. Instead, we found two novel heterozygous mutations at the junction of exon 10 and intron 11 of the LMNA gene. These mutations resulted in the production of progerin at a level substantially lower than that of HGPS. Our findings indicate that LMNA mutations may result in coronary artery disease presenting in the fourth to sixth decades along with short stature and a progeroid appearance resembling WS. The absence of early‐onset cataracts in this setting should suggest the diagnosis of progeroid laminopathy. This study illustrates the evolving genotype–phenotype relationship between the amount of progerin produced and the age of onset among the spectrum of restrictive dermopathy, HGPS, and atypical forms of WS.

Neurodevelopmental disorders among individuals with duplication of 4p13 to 4p12 containing a GABA A receptor subunit gene cluster

Recent studies have shown that certain copy number variations (CNV) are associated with a wide range of neurodevelopmental disorders, including autism spectrum disorders (ASD), bipolar disorder and intellectual disabilities. Implicated regions and genes have comprised a variety of post synaptic complex proteins and neurotransmitter receptors, including gamma-amino butyric acid A (GABAA). Clusters of GABAA receptor subunit genes are found on chromosomes 4p12, 5q34, 6q15 and 15q11-13. Maternally inherited 15q11-13 duplications among individuals with neurodevelopmental disorders are well described, but few case reports exist for the other regions. We describe a family with a 2.42 Mb duplication at chromosome 4p13 to 4p12, identified in the index case and other family members by oligonucleotide array comparative genomic hybridization, that contains 13 genes including a cluster of four GABAA receptor subunit genes. Fluorescent in-situ hybridization was used to confirm the duplication. The duplication segregates with a variety of neurodevelopmental disorders in this family, including ASD (index case), developmental delay, dyspraxia and ADHD (brother), global developmental delays (brother), learning disabilities (mother) and bipolar disorder (maternal grandmother). In addition, we identified and describe another individual unrelated to this family, with a similar duplication, who was diagnosed with ASD, ADHD and borderline intellectual disability. The 4p13 to 4p12 duplication appears to confer a susceptibility to a variety of neurodevelopmental disorders in these two families. We hypothesize that the duplication acts through a dosage effect of GABAA receptor subunit genes, adding evidence for alterations in the GABAergic system in the etiology of neurodevelopmental disorders.

Maternal uniparental disomy of chromosome 4 in a patient with limb-girdle muscular dystrophy 2E confirmed by SNP array technology.

Cottrell CE, Mendell J, Hart‐Kothari M, Ell D, Thrush DL, Astbury C, Pastore M, Gastier‐Foster JM, Pyatt RE. Maternal uniparental disomy of chromosome 4 in a patient with limb‐girdle muscular dystrophy 2E confirmed by SNP array technology.

Unexpected detection of dystrophin gene deletions by array comparative genomic hybridization

Array comparative genomic hybridization has increasingly become the standard of care to evaluate patients for genomic imbalance. As the patient population evaluated by microarray expands, there is certain to be an increase in the detection of unexpected, yet common diseases. When array results predict a late‐onset disorder or cancer predisposition, it becomes a challenge for physicians and counselors to adequately address with patients. Included in this study were three patients described with nonspecific phenotypic findings who underwent microarray testing to better define their disease etiology. An unexpected deletion within the dystrophin gene was observed in each case, despite that no patient was suspected of a dystrophinopathy at the time of testing. The patients included an 8‐day‐old male with a dystrophin deletion predictive of Becker muscular dystrophy, an 18‐month old female found to be the carrier of deletion, and a 4‐year‐8‐month‐old male with a deletion predictive of Duchenne muscular dystrophy. In this circumstance it becomes difficult to counsel the family, as well as to predict disease course when underlying medical conditions may exist. However, early detection may enable the patient to receive proactive treatment, and allows for screening of at‐risk family members. Ultimately, it is up to the clinician to promote informed decision‐making within the family prior to testing, and ensure that adequate counseling is provided during follow‐up.

MCPH1 deletion in a newborn with severe microcephaly and premature chromosome condensation

A newborn with severe microcephaly and a history of parental consanguinity was referred for cytogenetic analysis and subsequently for genetic evaluation. While a 46,XY karyotype was eventually obtained, premature chromosome condensation was observed. A head MRI confirmed primary microcephaly. This combination of features focused clinical interest on the MCPH1 gene and directed genetic testing by sequence analysis and duplication/deletion studies disclosed a homozygous deletion of exons 1-11 of the MCPH1 gene. This case illustrates a strength of standard cytogenetic evaluation in directing molecular testing to a single target gene in this disorder, allowing much more rapid diagnosis at a substantial cost savings for this family.

Role of CFTR mutation analysis in the diagnostic algorithm for cystic fibrosis

BackgroundThe cystic fibrosis transmembrane conductance regulator (CFTR) gene mutation identification is being used with increased frequency to aid in the diagnosis of cystic fibrosis (CF) in those suspected with CF. Aim of this study was to identify diagnostic outcomes when CFTR mutational analysis was used in CF diagnosis. CFTR mutational analysis results were also compared with sweat chloride results.MethodsThis study was done on all patients at our institution who had CFTR mutation analysis over a sevenyear period since August 2006.ResultsA total of 315 patients underwent CFTR mutational analysis. Fifty-one (16.2%) patients had two mutations identified. Among them 32 had positive sweat chloride levels (≥60 mmol/L), while seven had borderline sweat chloride levels (40-59 mmol/L). An additional 70 patients (22.3%) had only one mutation identified. Among them eight had positive sweat chloride levels, and 17 had borderline sweat chloride levels. Fifty-five patients (17.5%) without CFTR mutations had either borderline (n=45) or positive (n=10) sweat chloride results. Three patients with a CF phenotype had negative CFTR analysis but elevated sweat chloride levels. In eighty-three patients (26.4%) CFTR mutational analysis was done without corresponding sweat chloride testing.ConclusionsAlthough CFTR mutation analysis has improved the diagnostic capability for CF, its use either as the first step or the only test to diagnose CFTR dysfunction should be discouraged and CF diagnostic guidelines need to be followed.