Risk assessment models in genetics clinic for array comparative genomic hybridization: Clinical information can be used to predict the likelihood of an abnormal result in patients.

Array comparative genomic hybridization (aCGH) testing can diagnose chromosomal microdeletions and duplications too small to be detected by conventional cytogenetic techniques. We need to consider which patients are more likely to receive a diagnosis from aCGH testing versus patients that have lower likelihood and may benefit from broader genome wide scanning. We retrospectively reviewed charts of a population of 200 patients, 117 boys and 83 girls, who underwent aCGH testing in Genetics Clinic at Rhode Island hospital between 1 January/2008 and 31 December 2010. Data collected included sex, age at initial clinical presentation, aCGH result, history of seizures, autism, dysmorphic features, global developmental delay/intellectual disability, hypotonia and failure to thrive. aCGH analysis revealed abnormal results in 34 (17%) and variants of unknown significance in 24 (12%). Patients with three or more clinical diagnoses had a 25.0% incidence of abnormal aCGH findings, while patients with two or fewer clinical diagnoses had a 12.5% incidence of abnormal aCGH findings. Currently, we provide families with a range of 10-30% of a diagnosis with aCGH testing. With increased clinical complexity, patients have an increased probability of having an abnormal aCGH result. With this, we can provide individualized risk estimates for each patient.

A novel familial 11p15.4 microduplication associated with intellectual disability, dysmorphic features, and obesity with involvement of the ZNF214 gene.

We evaluated a patient with mild intellectual disability, obesity, overgrowth, and dysmorphic features. Array comparative genomic hybridization (aCGH) analysis showed a single copy number increase of a BAC clone in the 11p15.4 region. Oligonucleotide aCGH refined the duplication to approximately 2.29 megabases (Mb) in size. Testing the parents revealed that the father, who had learning disabilities and overgrowth, also had the 11p15.4 duplication, and the mother had a normal microarray. In addition, the patient's brother and grandmother all share clinical features with the proband and tested positive for the duplication. The duplicated region (Chr11:6,934,067-9,220,605) encompasses 29 genes, including the ZNF214 gene, which has been postulated to play a role in Beckwith-Wiedemann syndrome [Alders et al., 2000]. This three-generation pedigree outlines features of a novel microduplication syndrome.

Reviewing the evidence for mycophenolate mofetil as a new teratogen: case report and review of the literature.

Mycophenolate mofetil (MMF) (CellCept) is an immunosuppressant drug that is teratogenic in rats and rabbits. Reports of malformations in 13 offspring of women exposed to MMF in pregnancy raise concern that MMF is also a human teratogen. We report an additional child with malformations following prenatal exposure to MMF and review the other 13 reports. We identified a Cambodian male born at 31 weeks' gestation to a mother who had been treated for lupus nephritis with MMF from before conception to 12 weeks' gestational age. He had bilateral moderate-to-severe microtia, external auditory canal atresia, bilateral conductive hearing loss, mild microcephaly, and apparently normal development. Among the 14 MMF-exposed offspring now reported, the underlying maternal conditions were kidney transplantation (7), lupus nephritis (4), liver transplantation (1), heart transplantation (1), and recurrent erythema multiforme (1). All were exposed in early pregnancy. The most distinctive malformation was moderate-to-severe microtia or anotia (12), with external auditory canal atresia in 9. Other common craniofacial malformations and minor anomalies included orofacial clefts (7), hypertelorism (3), coloboma (3), and micrognathia (3). Six had cardiovascular malformations, of which three were either conotruncal or aortic arch defects. MMF dose, reported in 12 patients, was <1 g/day in 4 and 1 g or more/day in 8; no correlation between dose and phenotype severity was apparent. While case reports have limited value in identifying human teratogens, the unusual distribution of malformations among the 14 reported exposed offspring identifies a phenotype suggesting that MMF is likely a human teratogen.

Clinical significance of chimerism.

Twins have been previously classified as either monozygotic or dizygotic. In recent years, fascinating, non-traditional mechanisms of twinning have been uncovered. We define chimerism versus mosaicism, touch on chimerism in the animal world, and explain timing of chimerism in humans. In addition, we discuss when to suspect chimerism in patients, and how to proceed with diagnostic evaluation and confirmation.

Loss-of-function mutations in ATP6V0A2 impair vesicular trafficking, tropoelastin secretion and cell survival.

Autosomal recessive cutis laxa type 2 (ARCL2), a syndrome of growth and developmental delay and redundant, inelastic skin, is caused by mutations in the a2 subunit of the vesicular ATPase H+-pump (ATP6V0A2). The goal of this study was to define the disease mechanisms that lead to connective tissue lesions in ARCL2. In a new cohort of 17 patients, DNA sequencing of ATP6V0A2 detected either homozygous or compound heterozygous mutations. Considerable allelic and phenotypic heterogeneity was observed, with a missense mutation of a moderately conserved residue p.P87L leading to unusually mild disease. Abnormal N- and/or mucin type O-glycosylation was observed in all patients tested. Premature stop codon mutations led to decreased ATP6V0A2 mRNA levels by destabilizing the mutant mRNA via the nonsense-mediated decay pathway. Loss of ATP6V0A2 either by siRNA knockdown or in ARCL2 cells resulted in distended Golgi cisternae, accumulation of abnormal lysosomes and multivesicular bodies. Immunostaining of ARCL2 cells showed the accumulation of tropoelastin (TE) in the Golgi and in large, abnormal intracellular and extracellular aggregates. Pulse-chase studies confirmed impaired secretion and increased intracellular retention of TE, and insoluble elastin assays showed significantly reduced extracellular deposition of mature elastin. Fibrillin-1 microfibril assembly and secreted lysyl oxidase activity were normal in ARCL2 cells. TUNEL staining demonstrated increased rates of apoptosis in ARCL2 cell cultures. We conclude that loss-of-function mutations in ATP6V0A2 lead to TE aggregation in the Golgi, impaired clearance of TE aggregates and increased apoptosis of elastogenic cells.

Mutations in smooth muscle alpha-actin (ACTA2) lead to thoracic aortic aneurysms and dissections.

The major function of vascular smooth muscle cells (SMCs) is contraction to regulate blood pressure and flow. SMC contractile force requires cyclic interactions between SMC alpha-actin (encoded by ACTA2) and the beta-myosin heavy chain (encoded by MYH11). Here we show that missense mutations in ACTA2 are responsible for 14% of inherited ascending thoracic aortic aneurysms and dissections (TAAD). Structural analyses and immunofluorescence of actin filaments in SMCs derived from individuals heterozygous for ACTA2 mutations illustrate that these mutations interfere with actin filament assembly and are predicted to decrease SMC contraction. Aortic tissues from affected individuals showed aortic medial degeneration, focal areas of medial SMC hyperplasia and disarray, and stenotic arteries in the vasa vasorum due to medial SMC proliferation. These data, along with the previously reported MYH11 mutations causing familial TAAD, indicate the importance of SMC contraction in maintaining the structural integrity of the ascending aorta.

Microcephaly syndromes.

The objective of this article is to review microcephaly from a genetics point of view, especially with regard to the process of identification of syndromes in which small head circumference occurs. Microcephaly can be due to either genetic or environmental causes. It can be the only positive finding or may be part of a syndrome of congenital anomalies. The genetic etiology can be caused by autosomal dominant, autosomal recessive, or X-linked genes or various types of chromosome anomalies. Some of the gene mutations have been identified recently. Syndromic microcephaly is associated with a large number of conditions. Some can be diagnosed, or at least suspected, based on their characteristic facial dysmorphism, and others can be searched for using databases of genetic disorders.

Major congenital anomalies place extremely low birth weight infants at higher risk for poor growth and developmental outcomes.

BACKGROUND: Studies of growth and neurodevelopmental impairment in extremely low birth weight infants often exclude infants with major congenital anomalies; thus, there are few outcome data available on these infants. OBJECTIVES: The purpose of this work was to compare growth and neurodevelopmental outcomes of extremely low birth weight infants with major anomalies to extremely low birth weight infants without these findings. It was hypothesized that infants with severe anomalies would have worse growth, neurodevelopmental, and survival outcomes. METHODS: A retrospective cohort analysis was performed on 5920 extremely low birth weight infants surviving beyond 12 hours of life at 19 neonatal network centers between 1998 and 2001. Infants with significant anomalies were more likely to die before 18 to 22 months' corrected age. A total of 3705 children underwent neurodevelopmental and anthropometric evaluation at 18 to 22 months' corrected age. Statistical significance for unadjusted comparisons was determined by Wilcoxon tests for continuous variables and chi2 or Fisher's exact tests for categorical variables. Regression models were used to compare the outcomes after adjusting for potential confounders. RESULTS: Children with major congenital anomalies were more likely to have Bayley Mental Development Index scores of < or = 70, Psychomotor Development Index scores of < or = 70, neurodevelopmental impairment, moderate-to-severe cerebral palsy, length in the < or = 10th percentile, head circumference in the < or = 10th percentile, more rehospitalizations, and higher rates of early intervention use at 18 to 22 months' corrected age. CONCLUSIONS: At 18 to 22 months' corrected age, extremely low birth weight infants born with major anomalies have nearly twice the risk for neurodevelopmental impairment, increased risk of poor growth, and > 3 times greater risk of rehospitalization when compared with extremely low birth weight infants without major anomalies. This information may be valuable for counseling parents regarding the outcomes of these infants and for the facilitation of appropriate support and intervention services.

Recurrent infections, hypotonia, and mental retardation caused by duplication of MECP2 and adjacent region in Xq28.

OBJECTIVE: Our goal was to describe the neurologic and clinical features of affected males from families with X-linked patterns of severe mental retardation, hypotonia, recurrent respiratory infection, and microduplication of Xq28 that consistently includes the MECP2 (methyl-CpG binding protein 2) gene. STUDY DESIGN: To identify duplications, multiplex ligation-dependent probe amplification of the MECP2 gene was performed on male probands from families with X-linked mental retardation. The males either had linkage to Xq28 or had a phenotype consistent with previous reports involving Xq28 functional disomy. After detection of a duplication of MECP2, additional family members were tested to confirm the MECP2 duplication segregated with the affected phenotype, and X-inactivation studies were performed on carrier females. RESULTS: Six families with multiple affected males having MECP2 duplications were identified by multiplex ligation-dependent probe amplification, and the carrier mothers were subsequently shown to have highly skewed X inactivation. In 5 of 6 families, the microduplication extended proximally to include the L1 cell adhesion molecule gene. The primary clinical features associated with this microduplication are infantile hypotonia, recurrent respiratory infection, severe mental retardation, absence of speech development, seizures, and spasticity. CONCLUSIONS: Although many of the phenotypic features of our patients are rather nonspecific in cohorts of individuals with syndromic and nonsyndromic mental retardation, the proneness to infection is quite striking because the patients had normal growth and were not physically debilitated. Although the etiology of the infections is not understood, we recommend considering MECP2 dosage studies and a genetics referral in individuals with severe developmental delay and neurologic findings, especially when a history of recurrent respiratory ailments has been documented.

Permanent neonatal diabetes due to mutations in KCNJ11 encoding Kir6.2: patient characteristics and initial response to sulfonylurea therapy.

Permanent neonatal diabetes (PND) can be caused by mutations in the transcription factors insulin promoter factor (IPF)-1, eukaryotic translation initiation factor-2alpha kinase 3 (EIF2AK3), and forkhead box-P3 and in key components of insulin secretion: glucokinase (GCK) and the ATP-sensitive K(+) channel subunit Kir6.2. We sequenced the gene encoding Kir6.2 (KCNJ11) in 11 probands with GCK-negative PND. Heterozygous mutations were identified in seven probands, causing three novel (F35V, Y330C, and F333I) and two known (V59M and R201H) Kir6.2 amino acid substitutions. Only two probands had a family history of diabetes. Subjects with the V59M mutation had neurological features including motor delay. Three mutation carriers tested had an insulin secretory response to tolbutamide, but not to glucose or glucagon. Glibenclamide was introduced in increasing doses to investigate whether sulfonylurea could replace insulin. At a glibenclamide dose of 0.3-0.4 mg. kg(-1). day(-1), insulin was discontinued. Blood glucose did not deteriorate, and HbA(1c) was stable or fell during 2-6 months of follow-up. An oral glucose tolerance test performed in one subject revealed that glucose-stimulated insulin release was restored. Mutations in Kir6.2 were the most frequent cause of PND in our cohort. Apparently insulin-dependent patients with mutations in Kir6.2 may be managed on an oral sulfonylurea with sustained metabolic control rather than insulin injections, illustrating the principle of pharmacogenetics applied in diabetes treatment.

Adolescents and genetic testing: what do they think about it?

PURPOSE: To examine adolescents' attitudes toward screening for hereditary disorders. METHODS: A survey was distributed among 672 students in grades 10 to 12 attending a public suburban high school. The first part of the survey consisted of information about three diseases: familial breast cancer, Tay-Sachs disease, and hypercholesterolemia. The second part was a questionnaire developed by the authors, which explored students' attitudes toward testing for these diseases. Comparisons between and within groups were performed using X2 analysis. RESULTS: Out of the 672 surveys distributed, 361 were returned (54% response rate). Mean age of participants was 17 +/- 1 years. Most girls (67%) wanted to be tested for familial breast cancer. Girls were significantly more willing than boys to be tested for Tay-Sachs disease (23% vs. 13%, p <.002) and for hypercholesterolemia (54% vs. 39%, p <.001). Girls who had a relative with breast cancer were significantly more willing to be tested than other girls (p <.05). Individuals in the ethnic risk groups for Tay-Sachs disease were significantly more willing to be tested than those not in the ethnic risk groups (p <.001). However, only 33% of those in the ethnic risk groups for Tay-Sachs disease stated that they would either "definitely" or "probably" wish to be tested. Students who had a family history of high cholesterol were significantly more willing to be tested than those without a family history (70% vs. 34%, p <.0001). About 81% of the students with a family history of high cholesterol had never been referred for cholesterol testing. Only about 25% of participants stated that their attitude toward genetic testing was affected by concerns that genetic information might be misused by insurance companies/employers. CONCLUSIONS: The main motivator for genetic testing is having someone in the family affected by the disease in question. Adolescent girls are more willing to be tested for genetic diseases than are boys.