Anna Lehman
University of British Columbia, Medical Genetics, Faculty Member
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Cleft lip with or without palate (CLP) can be diagnosed antenatally through ultrasound, and may be categorised as apparently isolated versus associated with other malformations. Limited data exist on the long-term outcomes following... more
Cleft lip with or without palate (CLP) can be diagnosed antenatally through ultrasound, and may be categorised as apparently isolated versus associated with other malformations. Limited data exist on the long-term outcomes following antenatal diagnosis of apparently isolated CLP. This study examined the long-term post-natal outcomes of CLP when found in isolation antenatally, in order to determine the rates of unexpected additional anomalies, developmental delay or genetic syndromes. A retrospective chart review of antenatal and post-natal medical charts was completed for a ten-year period between January 2000 and December 2009. At least 2 years of available post-natal clinical information was required for inclusion in the study. A total of 97 cases of antenatally isolated CLP were ascertained. Fifteen pregnancies were terminated. Follow-up data were available for 81 liveborns, though 4 were lost to follow-up prior to 2 years of age. Twelve of the 77 children meeting study criteria were identified to have other major malformations and/or developmental disability either later in the pregnancy or post-natally. Findings included familial clefting syndromes, trisomy 21, autism spectrum disorders, brain malformations, fetal alcohol syndrome and Kabuki syndrome, among other findings. Another 11 children had additional anomalies of minor impact. Examples of findings include a perimembranous ventricular septal defect, mild unilateral optic nerve hypoplasia, mild pulmonary artery stenosis with a small atrial septal defect, and transient delays in fine and gross motor skills. No children with clefting of the lip only had major additional diagnoses.
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Intraflagellar transport (IFT) depends on two evolutionarily conserved modules, subcomplexes A (IFT-A) and B (IFT-B), to drive ciliary assembly and maintenance. All six IFT-A components and their motor protein, DYNC2H1, have been linked... more
Intraflagellar transport (IFT) depends on two evolutionarily conserved modules, subcomplexes A (IFT-A) and B (IFT-B), to drive ciliary assembly and maintenance. All six IFT-A components and their motor protein, DYNC2H1, have been linked to human skeletal ciliopathies, including asphyxiating thoracic dystrophy (ATD; also known as Jeune syndrome), Sensenbrenner syndrome, and Mainzer-Saldino syndrome (MZSDS). Conversely, the 14 subunits in the IFT-B module, with the exception of IFT80, have unknown roles in human disease. To identify additional IFT-B components defective in ciliopathies, we independently performed different mutation analyses: candidate-based sequencing of all IFT-B-encoding genes in 1,467 individuals with a nephronophthisis-related ciliopathy or whole-exome resequencing in 63 individuals with ATD. We thereby detected biallelic mutations in the IFT-B-encoding gene IFT172 in 12 families. All affected individuals displayed abnormalities of the thorax and/or long bones, as well as renal, hepatic, or retinal involvement, consistent with the diagnosis of ATD or MZSDS. Additionally, cerebellar aplasia or hypoplasia characteristic of Joubert syndrome was present in 2 out of 12 families. Fibroblasts from affected individuals showed disturbed ciliary composition, suggesting alteration of ciliary transport and signaling. Knockdown of ift172 in zebrafish recapitulated the human phenotype and demonstrated a genetic interaction between ift172 and ift80. In summary, we have identified defects in IFT172 as a cause of complex ATD and MZSDS. Our findings link the group of skeletal ciliopathies to an additional IFT-B component, IFT172, similar to what has been shown for IFT-A.
Research Interests: Biological Sciences, Humans, Mutation, Retinitis pigmentosa, Female, and 13 moreAnimals, Male, Cerebellar ataxia, Phenotype, European Continental Ancestry Group, Asian Continental Ancestry Group, Zebrafish, Amino Acid Sequence, Human Fibroblasts, Bone and Bones, Ectodermal Dysplasia, Molecular Sequence Data, and fibroblasts
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Proteolytic processing of the -amyloid precursor protein (APP) at the site is essential to generate A. BACE1, the major -secretase involved in cleaving APP, has been identified as a type 1 membrane-associated aspartyl protease. We have... more
Proteolytic processing of the -amyloid precursor protein (APP) at the site is essential to generate A. BACE1, the major -secretase involved in cleaving APP, has been identified as a type 1 membrane-associated aspartyl protease. We have cloned a 2.1-kb fragment upstream of the human BACE1 gene and identified key regions necessary for promoter activity. BACE1 gene expression is controlled by
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Adams-Oliver syndrome (AOS) is a rare developmental disorder characterized by the presence of aplasia cutis congenita (ACC) of the scalp vertex and terminal limb-reduction defects. Cardiovascular anomalies are also frequently observed.... more
Adams-Oliver syndrome (AOS) is a rare developmental disorder characterized by the presence of aplasia cutis congenita (ACC) of the scalp vertex and terminal limb-reduction defects. Cardiovascular anomalies are also frequently observed. Mutations in five genes have been identified as a cause for AOS prior to this report. Mutations in EOGT and DOCK6 cause autosomal-recessive AOS, whereas mutations in ARHGAP31, RBPJ, and NOTCH1 lead to autosomal-dominant AOS. Because RBPJ, NOTCH1, and EOGT are involved in NOTCH signaling, we hypothesized that mutations in other genes involved in this pathway might also be implicated in AOS pathogenesis. Using a candidate-gene-based approach, we prioritized DLL4, a critical NOTCH ligand, due to its essential role in vascular development in the context of cardiovascular features in AOS-affected individuals. Targeted resequencing of the DLL4 gene with a custom enrichment panel in 89 independent families resulted in the identification of seven mutations. A...
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Tracheobronchomegaly (Mounier-Kuhn Syndrome) is a rare disease characterized by tracheal enlargement and associated loss of elastic fibers in the trachea and main bronchi. MEDLINE, Index Medicus, and other databases were searched with... more
Tracheobronchomegaly (Mounier-Kuhn Syndrome) is a rare disease characterized by tracheal enlargement and associated loss of elastic fibers in the trachea and main bronchi. MEDLINE, Index Medicus, and other databases were searched with pre-defined criteria to identify cases of tracheobronchomegaly (TBM). Two new cases of TBM were also identified from the Provincial Medical Genetics Program of British Columbia. We identified 166 publications describing 365 occurrences of TBM. We observed that affected individuals could be grouped into subgroups according to clinical features. Type 1A (105 individuals) consists of infants who developed TBM after having undergone fetoscopic tracheal occlusion, and Type 1B patients (24 individuals) are infants and children who developed TBM after prolonged intubation. Type 2 individuals developed TBM following recurrent pulmonary infections (2A) (14 individuals) or pulmonary fibrosis (2B) (10 individuals). Type 3 represents TBM with evidence of extra-pulmonary elastolysis (18 individuals), and Type 4 denotes the development of TBM with no clear predisposing factors (196 individuals). Both of our patients had TBM and evidence of extra-pulmonary elastolysis. As well, one patient had a mildly dilated aortic root, which is a previously unreported co-occurrence. We introduce a novel classification scheme, which may sort patients into etiologically distinct groups, furthering our understanding of its pathogenesis and potentially, prevention or therapy. We also hypothesize that TBM and generalized elastolysis may have etiological commonalities, suggesting a need for further study.
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Proteolytic processing of the beta-amyloid precursor protein (APP) at the beta site is essential to generate Abeta. BACE1, the major beta-secretase involved in cleaving APP, has been identified as a type 1 membrane-associated aspartyl... more
Proteolytic processing of the beta-amyloid precursor protein (APP) at the beta site is essential to generate Abeta. BACE1, the major beta-secretase involved in cleaving APP, has been identified as a type 1 membrane-associated aspartyl protease. We have cloned a 2.1-kb fragment upstream of the human BACE1 gene and identified key regions necessary for promoter activity. BACE1 gene expression is controlled by a TATA-less promoter. The region of bp -619 to +46 is the minimal promoter to control the transcription of the BACE1 gene. Several putative cis-acting elements, such as a GC box, HSF-1, a PU box, AP1, AP2, and lymphokine response element, are found in the 5' flanking region of the BACE1 gene. Transcriptional activation and gel shift assays demonstrated that the BACE1 promoter contains a functional Sp1 response element, and overexpression of the transcription factor Sp1 potentiates BACE gene expression and APP processing to generate Abeta. Furthermore, Sp1 knockout reduced BACE...
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Proteolytic processing of the ß-amyloid precursor protein (APP) at the ß site is essential to generate Aß. BACE1, the major ß-secretase involved in cleaving APP, has been identified as a type 1 membrane-associated aspartyl protease. We... more
Proteolytic processing of the ß-amyloid precursor protein (APP) at the ß site is essential to generate Aß. BACE1, the major ß-secretase involved in cleaving APP, has been identified as a type 1 membrane-associated aspartyl protease. We have cloned a 2.1-kb fragment upstream of ...
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Given the high rate of psychiatric comorbidity with chronic fatigue syndrome (CFS), we considered two possible correlates of anxiety and depression: lack of illness legitimization and beliefs about limiting physical activity. A total of... more
Given the high rate of psychiatric comorbidity with chronic fatigue syndrome (CFS), we considered two possible correlates of anxiety and depression: lack of illness legitimization and beliefs about limiting physical activity. A total of 105 people diagnosed with CFS reported on their experiences with medical professionals and their beliefs about recovery and completed the depression and anxiety subscales of the Brief Symptom Inventory. Those who said that their physician did not legitimize their illness (36%) had higher depression and anxiety scores (P's<.05) than their counterparts. Those who believed that limiting their physical exertion was the path to recovery (55%) had lower depression and anxiety scores (P's<.01) than their counterparts. Lack of illness legitimization ranked high as a source of dissatisfaction for CFS patients, and it may aggravate psychiatric morbidity. Many CFS patients believed that staying within what they felt to be their physical limits wou...