Next generation sequencing identifies mutations in Atonal homolog 7 (ATOH7) in families with global eye developmental defects.

The atonal homolog 7 (ATOH7) gene encodes a transcription factor involved in determining the fate of retinal progenitor cells and is particularly required for optic nerve and ganglion cell development. Using a combination of autozygosity mapping and next generation sequencing, we have identified homozygous mutations in this gene, p.E49V and p.P18RfsX69, in two consanguineous families diagnosed with multiple ocular developmental defects, including severe vitreoretinal dysplasia, optic nerve hypoplasia, persistent fetal vasculature, microphthalmia, congenital cataracts, microcornea, corneal opacity and nystagmus. Most of these clinical features overlap with defects in the Norrin/ß-catenin signalling pathway that is characterized by dysgenesis of the retinal and hyaloid vasculature. Our findings document Mendelian mutations within ATOH7 and imply a role for this molecule in the development of structures at the front as well as the back of the eye. This work also provides further insights into the function of ATOH7, especially its importance in retinal vascular development and hyaloid regression.

Homozygous mutations in PXDN cause congenital cataract, corneal opacity, and developmental glaucoma.

Anterior segment dysgenesis describes a group of heterogeneous developmental disorders that affect the anterior chamber of the eye and are associated with an increased risk of glaucoma. Here, we report homozygous mutations in peroxidasin (PXDN) in two consanguineous Pakistani families with congenital cataract-microcornea with mild to moderate corneal opacity and in a consanguineous Cambodian family with developmental glaucoma and severe corneal opacification. These results highlight the diverse ocular phenotypes caused by PXDN mutations, which are likely due to differences in genetic background and environmental factors. Peroxidasin is an extracellular matrix-associated protein with peroxidase catalytic activity, and we confirmed localization of the protein to the cornea and lens epithelial layers. Our findings imply that peroxidasin is essential for normal development of the anterior chamber of the eye, where it may have a structural role in supporting cornea and lens architecture as well as an enzymatic role as an antioxidant enzyme in protecting the lens, trabecular meshwork, and cornea against oxidative damage.

Null mutations in LTBP2 cause primary congenital glaucoma.

Primary congenital glaucoma (PCG) is an autosomal-recessive condition characterized by high intraocular pressure (IOP), usually within the first year of life, which potentially could lead to optic nerve damage, globe enlargement, and permanent loss of vision. To date, PCG has been linked to three loci: 2p21 (GLC3A), for which the responsible gene is CYP1B1, and 1p36 (GLC3B) and 14q24 (GLC3C), for which the genes remain to be identified. Here we report that null mutations in LTBP2 cause PCG in four consanguineous families from Pakistan and in patients of Gypsy ethnicity. LTBP2 maps to chromosome 14q24.3 but is around 1.3 Mb proximal to the documented GLC3C locus. Therefore, it remains to be determined whether LTBP2 is the GLC3C gene or whether a second adjacent gene is also implicated in PCG. LTBP2 is the largest member of the latent transforming growth factor (TGF)-beta binding protein family, which are extracellular matrix proteins with multidomain structure. It has homology to fibrillins and may have roles in cell adhesion and as a structural component of microfibrils. We confirmed localization of LTBP2 in the anterior segment of the eye, at the ciliary body, and particularly the ciliary process. These findings reveal that LTBP2 is essential for normal development of the anterior chamber of the eye, where it may have a structural role in maintaining ciliary muscle tone.

An SCN9A channelopathy causes congenital inability to experience pain.

The complete inability to sense pain in an otherwise healthy individual is a very rare phenotype. In three consanguineous families from northern Pakistan, we mapped the condition as an autosomal-recessive trait to chromosome 2q24.3. This region contains the gene SCN9A, encoding the alpha-subunit of the voltage-gated sodium channel, Na(v)1.7, which is strongly expressed in nociceptive neurons. Sequence analysis of SCN9A in affected individuals revealed three distinct homozygous nonsense mutations (S459X, I767X and W897X). We show that these mutations cause loss of function of Na(v)1.7 by co-expression of wild-type or mutant human Na(v)1.7 with sodium channel beta(1) and beta(2) subunits in HEK293 cells. In cells expressing mutant Na(v)1.7, the currents were no greater than background. Our data suggest that SCN9A is an essential and non-redundant requirement for nociception in humans. These findings should stimulate the search for novel analgesics that selectively target this sodium channel subunit.

Umbilical vein oxytocin for the treatment of retained placenta (Release Study): a double-blind, randomised controlled trial.

BACKGROUND: Retained placenta is associated with post-partum haemorrhage. Meta-analysis has suggested that umbilical injection of oxytocin could increase placental expulsion without the need for a surgeon or anaesthetic. We assessed the effect of high-dose umbilical vein oxytocin as a treatment for retained placenta. METHODS: In this double-blind, placebo-controlled trial, haemodynamically stable women with a retained placenta for more than 30 min were recruited from 13 sites in the UK, Uganda, and Pakistan. 577 women were randomly assigned by a computer-generated randomisation list stratified by centre to 30 mL saline containing either 50 IU oxytocin (n=292) or 5 mL water (n=285), which was injected into the placenta through an umbilical vein catheter. All trial participants, study workers, and data handlers were masked to individual allocations. The primary outcome was the need for manual removal of the placenta. Analysis was by intention to treat. This study is registered, number ISRCTN 13204258. FINDINGS: The primary outcome was recorded for all participants. We detected no difference between the groups in the need for manual removal of placenta (oxytocin 179/292 [61.3%] vs placebo 177/285 [62.1%]; relative risk 0.98, 95% CI 0.87-1.12; p=0.84). The need for manual removal was higher in the UK (overall 250/361 [69%]) than in Uganda (90/190 [47%]) or Pakistan (16/26 [62%]). Adverse events did not differ between the two groups. INTERPRETATION: Umbilical oxytocin has no clinically significant effect on the need for manual removal for women with retained placenta. FUNDING: WHO, WellBeing of Women, Pakistan Higher Education Commission.

Homozygous FOXE3 mutations cause non-syndromic, bilateral, total sclerocornea, aphakia, microphthalmia and optic disc coloboma.

PURPOSE: To investigate the genetic basis of recessively-inherited congenital, non syndromic, bilateral, total sclerocornea in two consanguineous pedigrees, one from the Punjab province of Pakistan and the other from the Tlaxcala province of Mexico. METHODS: Ophthalmic examinations were conducted on each family member to confirm their diagnosis and magnetic resonance imaging (MRI) or ultrasonography of the eyes was performed on some family members. Genomic DNA was analyzed by homozygosity mapping using the Affymetrix 6.0 SNP array and linkage was confirmed with polymorphic microsatellite markers. Candidate genes were sequenced. RESULTS: A diagnosis of autosomal recessive sclerocornea was established for 7 members of the Pakistani and 8 members of the Mexican pedigrees. In the Pakistani family we established linkage to a region on chromosome 1p that contained Forkhead Box E3 (FOXE3), a strong candidate gene since FOXE3 mutations had previously been associated with various anterior segment abnormalities. Sequencing FOXE3 identified the previously reported nonsense mutation, c.720C>A, p.C240X, in the Pakistani pedigree and a novel missense mutation which disrupts an evolutionarily conserved residue in the forkhead domain, c.292T>C, p.Y98H, in the Mexican pedigree. Individuals with heterozygous mutations had no ocular abnormalities. MRI or ultrasonography confirmed that the patients with sclerocornea were also aphakic, had microphthalmia and some had optic disc coloboma. CONCLUSIONS: This is the fourth report detailing homozygous FOXE3 mutations causing anterior segment abnormalities in human patients. Previous papers have emphasized aphakia and microphthalmia as the primary phenotype, but we find that the initial diagnosis - and perhaps the only one possible in a rural setting - is one of non-syndromic, bilateral, total sclerocornea. Dominantly inherited anterior segment defects have also been noted in association with heterozygous FOXE3 mutations. However the absence of any abnormalities in the FOXE3 heterozygotes described suggests that genetic background and environmental factors plays a role in the penetrance of the mutant allele.

Iatrogenic vesicovaginal fistula.

OBJECTIVE: To find the frequency of iatrogenic VVF in patients admitted for repair of VVF in Lady Willingdon Hospital, Lahore. STUDY DESIGN: An observational study. PLACE AND DURATION OF STUDY: Lady Willingdon Hospital, Lahore, from January 2007 to December 2008. METHODOLOGY: All cases of VVF treated at the centre during the study period were included in the study. The patients were admitted and evaluated through detailed history, physical examination, relevant investigations and evaluation under general anaesthesia (EUA). Iatrogenic VVF was defined as the one following gynaecological procedure. Repair was done through abdominal or vaginal route based on the findings of EUA. RESULTS of repair were noted and analyzed using SPSS version 12. RESULTS: Iatrogenic cases of VVF made more than half of the total cases (54%) while 46% were due to obstructed labour. Women under the age of 40 years, made up 77% of the total cases. The success rate for repair of VVF was 87%. CONCLUSION: This study shows that iatrogenic injuries in women under 40 years of age form a major share in the etiology of VVF requiring a check on the experience of surgeons doing the gynaecological and obstetrical surgeries in a developing country.

Intrauterine Fetal Blood Transfusion (IUBT) for Rh Incompatibility - 12 Years' Experience from Pakistan.

OBJECTIVE: To determine the perinatal outcome of pregnancies complicated by Rh-alloimmunisation, requiring intrauterine blood transfusion. STUDY DESIGN: Observational study. PLACE AND DURATION OF STUDY: Feto-maternal Unit of Gene Tech Laboratory, Lahore, from 2007 to 2019. METHODOLOGY: A retrospective analysis was done on the data of cases of intrauterine, intravascular blood transfusion given to at-risk foetuses to correct foetal anaemia due to Rh-alloimmunisation or parvovirus B19. All cases, who were eligible to receive IUBT were included in the study. Cases where historic data was not available have been excluded. RESULTS: A total of 305 intrauterine blood transfusion (IUBT) procedures were performed on 127 foetuses. The gestational age ranged from 18-32 weeks at the time of referral. Infra-hepatic part of umbilical vein was preferred for transfusion, but in some cases of anterior placenta, the cord insertion was approached with exception of only two cases where intra-cardiac route was employed. In this study, 71.6% of the babies survived, 14.2% were loss to follow and 14.2% died. CONCLUSION: IUBT is a safe procedure, especially when performed by experienced hands, and helps save the foetuses at risk. Mothers with Rh-alloimmunisation should be referred before developing hydrops fetalis for better outcome. Key Words: Red cell alloimmunisation, Intrauterine intravascular blood transfusion, Foetal anaemia.

Refinement of the locus for hereditary congenital facial palsy on chromosome 3q21 in two unrelated families and screening of positional candidate genes.

Hereditary congenital facial palsy (HCFP) is an autosomal-dominant disorder consisting of paresis or paralysis of the VIIth (facial) cranial nerve. Genetic heterogeneity for this disorder has been suggested based on linkage analysis in two large Dutch families. Two loci have been identified, one on chromosome 3q21.2-q22.1 (HCFP1) and another on chromosome 10q21.3-q22.1 (HCFP2). Here, we report linkage analysis in a large Pakistani family with dominant congenital facial palsy. A region cosegregating with the disorder was identified on the long arm of chromosome 3, which overlaps with the previously identified HCFP1 locus on chromosome 3q21-q22, thus confirming the involvement of this locus in HCFP. The critical region could be reduced from 5.7 to 3.0 cM between the markers D3S3607 and GDB ID:11524500. In addition, mutation analysis on seven candidate genes: KLF15, FLJ40083, PODXL2, TMCC1, PLEXIN-A1, PLEXIN-D1, and GATA-2, was performed. All genes are located within the critical interval of the Dutch HCFP1 family. The genes PODXL2, PLEXIN-D1, GATA-2, and TMCC1 are also located within the smaller critical interval of the Pakistani HCFP family. Based on the results obtained, all seven genes could be excluded as causative genes in HCFP.

Pakistani mothers' and fathers' experiences and understandings of the diagnosis of Down syndrome for their child.

Down syndrome (DS) is a relatively common chromosomal condition, which can be diagnosed prenatally. However, little is known about the diagnosis of the condition in developing countries. This qualitative study explored parents' experiences of the diagnosis of DS in Pakistan. Fifteen mothers and fifteen fathers of children with DS had semi-structured interviews, which were analysed using thematic analysis. All the parents received their child's diagnosis after birth, ranging from the postnatal period to 7 years of age. Parents recalled receiving little or no information at the time of diagnosis, leading to misunderstandings about the cause and nature of their child's condition. Some parents referred to their child being "Mongol" and were unaware of "Down syndrome" as the more appropriate term for the condition. Use of such terms for DS restricted parents' ability to source further information about the condition. Many parents showed poor understanding of the aetiology and prognosis of the condition. Improved training for healthcare professionals in recognising key features of DS in the neonatal period or in early childhood could enable earlier diagnosis of the condition. In addition, provision of accurate information in a sensitive manner following diagnosis could enable parents to optimise their child's well-being.

Experiences of parents with a child with Down syndrome in Pakistan and their views on termination of pregnancy.

It has been argued that Down syndrome (DS) is as much a cultural creation as a biomedical condition, yet the majority of research in this area has been conducted in 'Western' cultures. This study explored parents' experiences of their child with DS in Pakistan and their views on abortion for the condition. Thirty mothers and fathers of children with DS took part in qualitative interviews. Transcripts were thematically analysed. Parents used Islamic discourse to frame positive personal meanings of their child's condition. These were contrasted with personal experiences of stigmatisation and rejection by family and community. An ambivalent cultural stereotype was revealed that characterised people with DS as abnormal and objects of pity but also as being closer to God and bringers of good fortune. Views on termination varied, but parents were generally supportive of the availability of abortion for DS due to the social stigmatisation they experienced. The findings reveal how parents negotiated their religious beliefs alongside personal experiences to inform personal views on abortion for DS. Advice to other parents about termination was rooted in Islamic discourse but emphasised pragmatic concerns about the impact of having a family member with intellectual disability in Pakistan.

Founder mutations and genotype-phenotype correlations in Meckel-Gruber syndrome and associated ciliopathies.

BACKGROUND: Meckel-Gruber syndrome (MKS) is an autosomal recessive lethal condition that is a ciliopathy. MKS has marked phenotypic variability and genetic heterogeneity, with mutations in nine genes identified as causative to date. METHODS: Families diagnosed with Meckel-Gruber syndrome were recruited for research studies following informed consent. DNA samples were analyzed by microsatellite genotyping and direct Sanger sequencing. RESULTS: We now report the genetic analyses of 87 individuals from 49 consanguineous and 19 non-consanguineous families in an unselected cohort with reported MKS, or an associated severe ciliopathy in a kindred. Linkage and/or direct sequencing were prioritized for seven MKS genes (MKS1, TMEM216, TMEM67/MKS3, RPGRIP1L, CC2D2A, CEP290 and TMEM237) selected on the basis of reported frequency of mutations or ease of analysis. We have identified biallelic mutations in 39 individuals, of which 13 mutations are novel and previously unreported. We also confirm general genotype-phenotype correlations. CONCLUSIONS: TMEM67 was the most frequently mutated gene in this cohort, and we confirm two founder splice-site mutations (c.1546 + 1 G > A and c.870-2A > G) in families of Pakistani ethnic origin. In these families, we have also identified two separate founder mutations for RPGRIP1L (c. 1945 C > T p.R649X) and CC2D2A (c. 3540delA p.R1180SfsX6). Two missense mutations in TMEM67 (c. 755 T > C p.M252T, and c. 1392 C > T p.R441C) are also probable founder mutations. These findings will contribute to improved genetic diagnosis and carrier testing for affected families, and imply the existence of further genetic heterogeneity in this syndrome.

'All is done by Allah'. Understandings of Down syndrome and prenatal testing in Pakistan.

Understanding the psychosocial impact of a congenital condition such as Down syndrome on affected individuals and their family requires an understanding of the cultural context in which they are situated. This study carried out in 2008 used Q-Methodology to characterize understandings of Down syndrome (DS) in Pakistan in a sample of health professionals, researchers and parents of children with the condition. Fifty statements originally developed for a UK study and translated into Urdu were Q-sorted by 60 participants. The use of factor analytic techniques identified three independent accounts and qualitative data collected during the Q-sorting exercise supported their interpretation. In two accounts, the 'will of God' was central to an understanding of the existence of people with DS although perceptions about the value and quality of life of the affected individual differed significantly between these accounts as did views about the impact on the family. The third account privileged a more 'scientific worldview' of DS as a genetic abnormality but also a belief that society can further contribute to disabling those affected. Attitudes towards prenatal testing and termination of pregnancy demonstrated that a belief in the will of Allah was not necessarily associated with a rejection of these technologies. Accounts reflect the religious, cultural and economic context of Pakistan and issues associated with raising a child with a learning disability in that country.

Mpdz null allele in an avian model of retinal degeneration and mutations in human leber congenital amaurosis and retinitis pigmentosa.

PURPOSE: To identify the defective gene in the sex-linked, recessively inherited retinal dysplasia and degeneration (rdd) chicken and to search for the human equivalent disease. METHODS: Microsatellites from chicken chromosome Z were genotyped in 77 progeny of a carrier male (rdd/+) and an affected female (rdd/W), and candidate genes were sequenced. Retinal cross-sections from rdd and wild-type birds were analyzed by immunohistology. The human orthologous gene was screened in a panel of archival DNAs from 276 patients with retinitis pigmentosa (RP) or Leber congenital amaurosis (LCA) using melting curve analysis and DNA sequencing. RESULTS: The rdd locus was refined to an approximately 3-Mb region on chromosome Z. Sequence analysis identified a C→T change in the mpdz gene that created a premature stop codon (c.1372C→T, p.R458X), which segregated with the disease phenotype. As expected, the full-length mpdz protein was absent in rdd retinas, but in wild-type birds, it localized to the retinal outer limiting membrane, where it may have a role in the interactions between photoreceptors and Müller glia cells. The screen to identify the human equivalent disease found 10 heterozygous variants in the orthologous gene in patients with RP (three missense and two null alleles) and LCA (four missense and one null allele). CONCLUSIONS: These findings reveal that MPDZ is essential for normal development of the retina and may have a role in maintaining photoreceptor integrity. The identification of human mutations suggests that MPDZ plays a role in human retinal disease, but the precise nature of this role remains to be determined.

Genetic heterogeneity for recessively inherited congenital cataract microcornea with corneal opacity.

PURPOSE: To investigate whether three consanguineous families from the Punjab province of Pakistan, with affected members with recessively inherited congenital cataract microcornea with corneal opacity, are genetically homogeneous. METHODS: An ophthalmic examination was performed on each family member to establish the diagnosis. The two largest families were analyzed by homozygosity mapping using SNP arrays. Linkage was confirmed using polymorphic microsatellite markers, and logarithm of odds (LOD) scores were calculated. Candidate genes were prioritized using the ENDEAVOUR program. RESULTS: Autosomal recessive congenital cataract-microcornea with corneal opacity mapped to chromosome 10cen for family MEP57 and to either chromosomes 2ptel or 20p for family MEP60. For MEP57, the refined interval was 36.8 Mb flanked by D10S1208 (35.3 Mb) and D10S676 (72.1 Mb). For MEP60, the interval containing the mutation was either 6.7 Mb from the telomere of chromosome 2 to marker D2S281 or 3.8 Mb flanked by D20S906 (1.5 Mb) and D20S835 (5.3 Mb). Maximum multipoint LOD scores of 3.09, 1.94, and 3.09 were calculated at D10S567, D2S281, and D20S473 for families MEP57 and MEP60. Linkage to these loci was excluded for family MEP68. SLC4A11 was excluded as a candidate gene for the observed phenotype in MEP60. CONCLUSIONS: The authors have identified two new loci, one on chromosome 10cen and the other on 2ptel or 20p, that are associated with recessively inherited congenital cataract-microcornea with corneal opacity. This phenotype is genetically heterogeneous in the Pakistani population. Further genetic studies of this kind, combined with a detailed phenotypic description, will contribute to more precise classification criteria for anterior segment disease.

Genotype-phenotype correlation for leber congenital amaurosis in Northern Pakistan.

OBJECTIVES: To report the genetic basis of Leber congenital amaurosis (LCA) in northern Pakistan and to describe the phenotype. METHODS: DNA from 14 families was analyzed using single-nucleotide polymorphism and microsatellite genotyping and direct sequencing to determine the genes and mutations involved. The history and examination findings from 64 affected individuals were analyzed to show genotype-phenotype correlation and phenotypic progression. RESULTS: Homozygous mutations were found in RPGRIP1 (4 families), AIPL1 and LCA5 (3 families each), and RPE65, CRB1, and TULP1 (1 family each). Six of the mutations are novel. An additional family demonstrated linkage to the LCA9 locus. Visual acuity, severe keratoconus, cataract, and macular atrophy were the most helpful features in predicting the genotype. Many of the phenotypic variables became more prevalent with increasing age. CONCLUSIONS: Leber congenital amaurosis in northern Pakistan is genetically heterogeneous. Mutations in RPGRIP1, AIPL1, and LCA5 accounted for disease in 10 of the 14 families. This study illustrates the differences in phenotype, for both the anterior and posterior segments, seen between patients with identical or different mutations in the LCA genes and also suggests that at least some of the phenotypic variation is age dependent. CLINICAL RELEVANCE: The LCA phenotype, especially one including different generations in the same family, may be used to refine a molecular diagnostic strategy.