Clinical and molecular heterogeneity of syndromic hypothalamic hamartoma.

Two children are presented who have a distinct syndrome of multiple buccolingual frenula, a stiff and short fifth finger with small nails, a hypothalamic hamartoma, mild to moderate neurological impairment, and mild endocrinological symptoms. No variant assessed to be pathogenic or likely pathogenic was detected in the GLI3 gene in either child. This syndrome appears to be distinct from the inherited Pallister-Hall syndrome associated with GLI3 variants, which is characterized by hypothalamic hamartoma, mesoaxial polydactyly, and other anomalies. In the individuals described here, manifestations outside of the central nervous system were milder and the mesoaxial polydactyly, which is common in individuals with Pallister-Hall syndrome, was absent. Instead, these children had multiple buccolingual frenula together with the unusual appearance of the fifth digit. It remains unclear whether these two individuals represent a separate nosologic entity or if they represent a milder manifestation of one of the more severe syndromes associated with a hypothalamic hamartoma.

Pulmonary Cystic Echinococcosis in a Child Presenting in the United Kingdom with Fever and Chest Pain: A Brief Report and Discussion on Management.

Cystic echinococcosis is a zoonosis caused by the larvae of Echinococcus granulosus . Pulmonary disease may be asymptomatic until the cyst ruptures or becomes secondarily infected. We report a case of pulmonary cystic echinococcosis presenting in the United Kingdom, with discussion on management: optimum antihelminthic agent, length of treatment and type of operative intervention. Treatment should be individualized to the clinical scenario.

Cervical lymph nodes and ovarian teratomas as germinal centres in NMDA receptor-antibody encephalitis.

Autoantibodies against the extracellular domain of the N-methyl-d-aspartate receptor (NMDAR) NR1 subunit cause a severe and common form of encephalitis. To better understand their generation, we aimed to characterize and identify human germinal centres actively participating in NMDAR-specific autoimmunization by sampling patient blood, CSF, ovarian teratoma tissue and, directly from the putative site of human CNS lymphatic drainage, cervical lymph nodes. From serum, both NR1-IgA and NR1-IgM were detected more frequently in NMDAR-antibody encephalitis patients versus controls (both P < 0.0001). Within patients, ovarian teratoma status was associated with a higher frequency of NR1-IgA positivity in serum (OR = 3.1; P < 0.0001) and CSF (OR = 3.8, P = 0.047), particularly early in disease and before ovarian teratoma resection. Consistent with this immunoglobulin class bias, ovarian teratoma samples showed intratumoral production of both NR1-IgG and NR1-IgA and, by single cell RNA sequencing, contained expanded highly-mutated IgA clones with an ovarian teratoma-restricted B cell population. Multiplex histology suggested tertiary lymphoid architectures in ovarian teratomas with dense B cell foci expressing the germinal centre marker BCL6, CD21+ follicular dendritic cells, and the NR1 subunit, alongside lymphatic vessels and high endothelial vasculature. Cultured teratoma explants and dissociated intratumoral B cells secreted NR1-IgGs in culture. Hence, ovarian teratomas showed structural and functional evidence of NR1-specific germinal centres. On exploring classical secondary lymphoid organs, B cells cultured from cervical lymph nodes of patients with NMDAR-antibody encephalitis produced NR1-IgG in 3/7 cultures, from patients with the highest serum NR1-IgG levels (P < 0.05). By contrast, NR1-IgG secretion was observed neither from cervical lymph nodes in disease controls nor in patients with adequately resected ovarian teratomas. Our multimodal evaluations provide convergent anatomical and functional evidence of NMDAR-autoantibody production from active germinal centres within both intratumoral tertiary lymphoid structures and traditional secondary lymphoid organs, the cervical lymph nodes. Furthermore, we develop a cervical lymph node sampling protocol that can be used to directly explore immune activity in health and disease at this emerging neuroimmune interface.

UNC45A deficiency causes microvillus inclusion disease-like phenotype by impairing myosin VB-dependent apical trafficking.

Variants in the UNC45A cochaperone have been recently associated with a syndrome combining diarrhea, cholestasis, deafness, and bone fragility. Yet the mechanism underlying intestinal failure in UNC45A deficiency remains unclear. Here, biallelic variants in UNC45A were identified by next-generation sequencing in 6 patients with congenital diarrhea. Corroborating in silico prediction, variants either abolished UNC45A expression or altered protein conformation. Myosin VB was identified by mass spectrometry as client of the UNC45A chaperone and was found misfolded in UNC45AKO Caco-2 cells. In keeping with impaired myosin VB function, UNC45AKO Caco-2 cells showed abnormal epithelial morphogenesis that was restored by full-length UNC45A, but not by mutant alleles. Patients and UNC45AKO 3D organoids displayed altered luminal development and microvillus inclusions, while 2D cultures revealed Rab11 and apical transporter mislocalization as well as sparse and disorganized microvilli. All those features resembled the subcellular abnormalities observed in duodenal biopsies from patients with microvillus inclusion disease. Finally, microvillus inclusions and shortened microvilli were evidenced in enterocytes from unc45a-deficient zebrafish. Taken together, our results provide evidence that UNC45A plays an essential role in epithelial morphogenesis through its cochaperone function of myosin VB and that UNC45A loss causes a variant of microvillus inclusion disease.

Spatiotemporal analysis of human intestinal development at single-cell resolution.

Development of the human intestine is not well understood. Here, we link single-cell RNA sequencing and spatial transcriptomics to characterize intestinal morphogenesis through time. We identify 101 cell states including epithelial and mesenchymal progenitor populations and programs linked to key morphogenetic milestones. We describe principles of crypt-villus axis formation; neural, vascular, mesenchymal morphogenesis, and immune population of the developing gut. We identify the differentiation hierarchies of developing fibroblast and myofibroblast subtypes and describe diverse functions for these including as vascular niche cells. We pinpoint the origins of Peyer's patches and gut-associated lymphoid tissue (GALT) and describe location-specific immune programs. We use our resource to present an unbiased analysis of morphogen gradients that direct sequential waves of cellular differentiation and define cells and locations linked to rare developmental intestinal disorders. We compile a publicly available online resource, spatio-temporal analysis resource of fetal intestinal development (STAR-FINDer), to facilitate further work.

A rare presentation of a paediatric sinonasal inverted papilloma.

Sinonasal inverted papilloma (IP) is a benign tumour with an extremely low incidence in children. We report the case of an 11-year-old Caucasian male presenting with recurrent right-sided epistaxis, nasal obstruction and a mass in the right nasal cavity. An initial diagnosis of a nasopharyngeal angiofibroma was considered; however, on detailed histological examination, the mass was found to be an inverted papilloma. This report aims to increase awareness of IP in the paediatric age group, as well as reinforcing the role of endoscopic surgery in the management of this condition.

Postmortem Genetic Testing for Cardiac Ion Channelopathies in Stillbirths.

BACKGROUND: Although stillbirth is a significant health problem worldwide, the definitive cause of death remains elusive in many cases, despite detailed autopsy. In this study of partly explained and unexplained stillbirths, we used next-generation sequencing to examine an extended panel of 35 candidate genes known to be associated with ion channel disorders and sudden cardiac death. METHODS AND RESULTS: We examined tissue from 242 stillbirths (≥22 weeks), including those where no definite cause of death could be confirmed after a full autopsy. We obtained high-quality DNA from 70 cases, which were then sequenced for a custom panel of 35 genes, 12 for inherited long- and short-QT syndrome genes (LQT1-LQT12 and SQT1-3), and 23 additional candidate genes derived from genome-wide association studies. We examined the functional significance of a selected variant by patch-clamp electrophysiological recording. No predicted damaging variants were identified in KCNQ1 (LQT1) or KCNH2 (LQT2). A rare putative pathogenic variant was found in KCNJ2(LQT7) in 1 case, and several novel variants of uncertain significance were observed. The KCNJ2 variant (p. R40Q), when assessed by whole-cell patch clamp, affected the function of the channel. There was no significant evidence of enrichment of rare predicted damaging variants within any of the candidate genes. CONCLUSIONS: Although a causative link is unclear, 1 putative pathogenic and variants of uncertain significance variant resulting in cardiac channelopathies was identified in some cases of otherwise unexplained stillbirth, and these variants may have a role in fetal demise. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01120886.

N-methyl-D-aspartate receptor antibody production from germinal center reactions: Therapeutic implications.

INTRODUCTION: N-methyl-D-aspartate receptor (NMDAR) antibody encephalitis is mediated by immunoglobulin G (IgG) autoantibodies directed against the NR1 subunit of the NMDAR. Around 20% of patients have an underlying ovarian teratoma, and the condition responds to early immunotherapies and ovarian teratoma removal. However, despite clear therapeutic relevance, mechanisms of NR1-IgG production and the contribution of germinal center B cells to NR1-IgG levels are unknown. METHODS: Clinical data and longitudinal paired serum NR1-reactive IgM and IgG levels from 10 patients with NMDAR-antibody encephalitis were determined. Peripheral blood mononuclear cells from these 10 patients, and two available ovarian teratomas, were stimulated with combinations of immune factors and tested for secretion of total IgG and NR1-specific antibodies. RESULTS: In addition to disease-defining NR1-IgG, serum NR1-IgM was found in 6 of 10 patients. NR1-IgM levels were typically highest around disease onset and detected for several months into the disease course. Moreover, circulating patient B cells were differentiated into CD19+ CD27++ CD38++ antibody-secreting cells in vitro and, from 90% of patients, secreted NR1-IgM and NR1-IgG. Secreted levels of NR1-IgG correlated with serum NR1-IgG (p < 0.0001), and this was observed across the varying disease durations, suggestive of an ongoing process. Furthermore, ovarian teratoma tissue contained infiltrating lymphocytes which produced NR1-IgG in culture. INTERPRETATION: Serum NR1-IgM and NR1-IgG, alongside the consistent production of NR1-IgG from circulating B cells and from ovarian teratomas suggest that ongoing germinal center reactions may account for the peripheral cell populations which secrete NR1-IgG. Cells participating in germinal center reactions might be a therapeutic target for the treatment of NMDAR-antibody encephalitis. Ann Neurol 2018;83:553-561.

Antenatally Detected Congenital Pulmonary Airway Malformations: The Oxford Experience.

Congenital airway pulmonary malformations are increasingly being diagnosed, but their management continues to remain controversial. Our approach has been to offer surgery to mitigate the risk of infection and possible malignancy. All patients routinely undergo a CT scan of the chest postnatally and once the diagnosis is confirmed, minimal access surgery is offered. Our anesthetists provide single-lung ventilation to enhance the operative view. We conducted a retrospective review over a 10-year period, during which 91 patients were prenatally suspected to have a cystic lung lesion. There were 88 live births of which 29 (33%) cases were initially managed conservatively based on CT findings. Five of these patients, however, became symptomatic needing surgery. A total of 64 (73%) patients underwent surgery with the most common lesions being congenital pulmonary airway malformations (CPAMs) (24), hybrid lesions (19), and pulmonary sequestrations (12). The median age at surgery was 5 months (1 day to 17 months). Using a minimal access approach, 41 (64%) cases were completed with 17 performed open from the onset. Open surgery was indicated in neonates who became symptomatic within the first few weeks of life as well as patients in respiratory distress that would not tolerate either single-lung ventilation or gas insufflation. There were six further conversions to open from minimal access surgery due to poor visualization or technical difficulties. One patient needed a perioperative blood transfusion and one patient had a more prolonged stay due to persistent air leak managed conservatively. Among asymptomatic patients, evidence of microscopic disease was seen, which included infection as well as two cases of tumors, one pleuropulmonary blastoma seen as part of a CPAM, and one rhabdomyomatous dysplasia seen in the CPAM component of a hybrid lesion. In our experience, excising asymptomatic lesions is safe with minimal complications. Single-lung ventilation in combination with thoracoscopy provides excellent vision. There is a risk of infection and a definite, albeit low, risk of malignancy, which may outweigh the benefits of conservative management.

Pathology of asymptomatic, prenatally diagnosed cystic lung malformations.

AIM: The management of asymptomatic congenital cystic lung malformations is controversial. Arguments for excision of asymptomatic lesions are the potential for infection and malignancy. Following antenatal detection, our institute performs a CT at 1month, clinic follow-up by 3months to discuss the controversial management, and offers surgery by 6months of age. We investigated the histopathology of asymptomatic lesions to determine whether there was evidence of subclinical infection or malignancy. METHODS: A retrospective review of prospectively collected antenatal congenital cystic lung malformations more than a 10year period (2005-2014) was conducted. Information was gathered from the antenatal registry and histopathology reports. Infection was defined by the presence of microabscesses or neutrophil/macrophage infiltration, as per histopathological criteria. MAIN RESULTS: From the cohort of 99 patients, the study focused on 69 asymptomatic lesions. These cases comprised 34 congenital pulmonary airway malformations (CPAM), 15 pulmonary sequestrations (PS), and 20 hybrid lesions. Eighteen cases (26%) had microscopic disease - 16 cases of infection and 2 tumors. The infectious cases comprised 7 with microabscesses and 9 with neutrophil/macrophage infiltration. There were two cases of tumors, namely pleuropulmonary blastoma. These tumors were followed up by the oncology team with regular imaging until 3years of age and clinical review thereafter. CONCLUSION: Twenty-six percent of antenatally detected, asymptomatic cystic lung malformations demonstrated either subclinical infection or malignancy. This information can be used for counseling parents and determining the method of treatment.

The pathology of congenital lung lesions.

The spectrum of complications associated with congenital lung malformation is wide. They can range from fetal hydrops in utero to postnatal problems of ventilation, obstruction and infection; presentation may occur from the neonatal period to adulthood. Many lesions will remain asymptomatic while at the other end of the complication spectrum, there is a small risk of neoplasia associated with some forms of cystic lung. A better understanding of the pathology has shown that bronchial atresia/obstruction is the likely hidden pathology underlying many congenital lung lesions leading to downstream cystic maldevelopment. Earlier diagnosis has led to increasing difficulties in ascribing malformations to conventional categories that were originally described in postnatal lungs. It is probably more important to be aware of the potential combination of vascular and airway connections and complications than to try and prescribe a classification of pulmonary lesions associated with rigid definitions.

The scale-up of a tissue engineered porous hydroxyapatite polymer composite scaffold for use in bone repair: an ovine femoral condyle defect study.

The development of an osteogenic bone graft substitute has important practical and cost implications in many branches of medicine where bone regeneration is required. Previous in vitro and small animal (murine) in vivo studies highlighted a porous hydroxyapatite/poly (DL-lactic acid) composite scaffold in combination with skeletal stem cells (SSCs) as a potential bone graft substitute candidate. The aim of the current study was to scale up the bone cell-scaffold construct to large animals and examine the potential for repair of a critical-sized defect via an ovine model. SSC seeded scaffolds (and unseeded scaffold controls) were implanted bilaterally into ovine femoral condyle critical defects for 3 months. A parallel in vitro analysis of ovine SSC seeded scaffolds was also performed. Post mortem mechanical indentation testing showed the bone strengths of the defect sites were 20% (controls) and 11% (SSC seeded scaffolds) those of normal cancellous bone (p < 0.01). MicroCT analysis demonstrated new bone formation within all defects with a mean increase of 13.4% in the control scaffolds over the SSC seeded scaffolds (p = 0.14). Histological examination confirmed these findings, with enhanced quality new bone within the control defects. This study highlights important issues and steps to overcome in scale-up and translation of tissue engineered products. The scaffold demonstrated encouraging results as an osteoconductive matrix; however, further work is required with cellular protocols before any human trials.

EXOSC3 mutations in pontocerebellar hypoplasia type 1: novel mutations and genotype-phenotype correlations.

BACKGROUND: Pontocerebellar hypoplasia (PCH) represents a group of neurodegenerative disorders with prenatal onset. Eight subtypes have been described thus far (PCH1-8) based on clinical and genetic features. Common characteristics include hypoplasia and atrophy of the cerebellum, variable pontine atrophy, and severe mental and motor impairments. PCH1 is distinctly characterized by the combination with degeneration of spinal motor neurons. Recently, mutations in the exosome component 3 gene (EXOSC3) have been identified in approximately half of the patients with PCH subtype 1. METHODS: We selected a cohort of 99 PCH patients (90 families) tested negative for mutations in the TSEN genes, RARS2, VRK1 and CASK. Patients in this cohort were referred with a tentative diagnose PCH type 1, 2, 4, 7 or unclassified PCH. Genetic analysis of the EXOSC3 gene was performed using Sanger sequencing. Clinical data, MR images and autopsy reports of patients positive for EXOSC3 mutations were analyzed. RESULTS: EXOSC3 mutations were found in twelve families with PCH subtype 1, and were not found in patients with other PCH subtypes. Identified mutations included a large deletion, nonsense and missense mutations. Examination of clinical data reveals a prolonged disease course in patients with a homozygous p.D132A mutation. MRI shows variable pontine hypoplasia in EXOSC3 mediated PCH, where the pons is largely preserved in patients with a homozygous p.D132A mutation, but attenuated in patients with other mutations. Additionally, bilateral cerebellar cysts were found in patients compound heterozygous for a p.D132A mutation and a nonsense allele. CONCLUSIONS: EXOSC3 mediated PCH shows clear genotype-phenotype correlations. A homozygous p.D132A mutation leads to PCH with possible survival into early puberty, and preservation of the pons. Compound heterozygosity for a p.D132A mutation and a nonsense or p.Y109N allele, a homozygous p.G31A mutation or a p.G135E mutation causes a more rapidly progressive course leading to death in infancy and attenuation of the ventral pons.Our findings imply a clear correlation between genetic mutation and clinical outcome in EXOSC3 mediated PCH, including variable involvement of the pons.

Eculizumab therapy for atypical haemolytic uraemic syndrome due to a gain-of-function mutation of complement factor B.

BACKGROUND: Atypical haemolytic uraemic syndrome (aHUS) is caused by dysregulated complement activation. A humanised anti-C5 monoclonal antibody has recently become available for treatment of this condition CASE-DIAGNOSIS/TREATMENT: We present the first description of an infant with an activating mutation of complement factor B successfully treated with eculizumab. On standard doses she had evidence of ongoing C5 cleavage despite a good clinical response. CONCLUSIONS: Eculizumab is effective therapy for aHUS associated with factor B mutations, but recommended doses may not be adequate for all patients.

Bilineal inheritance of PKD1 abnormalities mimicking autosomal recessive polycystic disease.

BACKGROUND: Dominant polycystic kidney disease is common and usually presents clinically in adulthood. Recessive polycystic kidney disease is much less common and frequently presents antenatally or in the neonatal period with severe renal involvement. These are usually thought of as clinically distinct entities but diagnostic confusion is not infrequent. CASE-DIAGNOSIS/TREATMENT: We describe an infant with antenatally diagnosed massive renal enlargement and oligohydramnios with no resolvable cysts on ultrasound scanning. He underwent bilateral nephrectomy because of respiratory compromise and poor renal function but died subsequently of overwhelming sepsis. Genetic analysis revealed that he had bilineal inheritance of abnormalities of PKD1 and no demonstrable abnormalities of PKD2 or PKHD1. CONCLUSIONS: Biallelic inheritance of abnormalities of PKD1 may causextremely severe disease resembling autosomal recessive polycystic kidney disease (ARPKD) which can result indiagnostic confusion. Accurate diagnosis is essential forgenetic counseling [corrected].

Cisplatin-induced haemolytic uraemic syndrome associated with a novel intronic mutation of CD46 treated with eculizumab.

A 2-year-old patient with a neuroblastoma developed haemolytic uraemic syndrome (HUS) following treatment with cisplatin and carboplatin. Following treatment with eculizumab, there was a substantial improvement in renal function with the recovery of the platelet count and the cessation of haemolysis. Subsequent investigations showed a novel, heterozygous CD46 splice site mutation with reduced peripheral blood neutrophil CD46 expression. Withdrawal of eculizumab was followed by the recurrence of disease activity, which resolved with re-introduction of therapy. Abnormal regulation of complement may be associated with other cases of cisplatin-induced HUS and treatment with eculizumab may be appropriate for other affected individuals.

Exome analysis resolves differential diagnosis of familial kidney disease and uncovers a potential confounding variant.

A girl aged 6 presented with haematuria and her sister (aged 5) presented with haematuria and proteinuria. Family history showed multiple individuals suffering from end stage renal failure from the paternal side of the pedigree. Following kidney biopsy in the father and paternal grandmother, the pathological diagnosis was of focal segmental glomerulosclerosis (FSGS). Exome sequencing was undertaken in the proband's sister and grandmother. Genetic variants shared by both affected individuals were interrogated to identify the genetic cause of disease. Candidate variants were then sequenced in all the family members to determine segregation with the disease. A mutation of COL4A5 known to cause Alport syndrome segregated with disease from the paternal side of the pedigree and a variant in NPHS1 was present in both paediatric cases and inherited from their mother. This study highlights the advantages of exome sequencing over single gene testing; disease presentation can be heterogeneous with several genes representing plausible candidates; candidate gene(s) may be unavailable as a diagnostic test; consecutive, single gene testing typically concludes once a single causal mutation is identified. In this family, we were able to confirm a diagnosis of Alport syndrome, which will facilitate testing in other family members.

The role of osteoblast cells in the pathogenesis of unicameral bone cysts.

PURPOSE: The pathogenesis of unicameral bone cysts (UBCs) remains largely unknown. Osteoclasts have been implicated, but the role of osteoblastic cells has, to date, not been explored. This study investigated the pathophysiology of UBCs by examining the interactions between the cyst fluid and human bone marrow stromal cells (hBMSCs) and the effect of the fluid on osteogenesis. METHODS: Fluid was aspirated from two UBCs and analysed for protein, electrolyte and cytokine levels. Graded concentrations of the fluid were used as culture media for hBMSCs to determine the effects of the fluid on hBMSC proliferation and osteogenic differentiation. The fibrocellular lining was analysed histologically and by electron microscopy. RESULTS: Alkaline phosphatase (ALP) staining of hBMSCs that were cultured in cyst fluid demonstrated increased cell proliferation and osteogenic differentiation compared to basal media controls. Biochemical analysis of these hBMSCs compared to basal controls confirmed a marked increase in DNA content (as a marker of proliferation) and ALP activity (as a marker of osteogenic differentiation) which was highly significant (p < 0.001). Osteoclasts were demonstrated in abundance in the cyst lining. The cyst fluid cytokine profile revealed levels of the pro-osteoclast cytokines IL-6, MIP-1α and MCP-1 that were 19×, 31× and 35× greater than those in reference serum. CONCLUSIONS: Cyst fluid promoted osteoblastic growth and differentiation. Despite appearing paradoxical that the cyst fluid promoted osteogenesis, osteoblastic cells are required for osteoclastogenesis through RANKL signalling. Three key cytokines in this pathway (IL-6, MIP-1α, MCP-1) were highly elevated in cyst fluid. These findings may hold the key to the pathogenesis of UBCs, with implications for treatment methods.

Intrapericardial teratoma in neonates: a surgical emergency.

Primary cardiac tumors are very rare, with a reported incidence of 0.15% to 0.2% in autopsy series. They can be life threatening because of myocardial compression and ventricular dysfunction. Once diagnosed during pregnancy, the clinical condition of the baby is monitored because of the risk of rupture of the tumor capsule. The authors report a rare case of a neonate who presented with respiratory and cardiac compromise due to cardiac tamponade necessitating emergency exploration of the pericardium and excision of tumor. A well-encapsulated tumor measuring around 5 cm and bigger than the heart was completely excised. This was diagnosed to be an immature teratoma. Follow-up echocardiogram was normal, and on serial monitoring, alpha-fetoprotein was within normal limits. The baby was discharged home with no complications. Intrapericardial teratoma in neonates is a surgical emergency if presented with significant pericardial effusion. It can be a challenge if diagnosed in utero with rupture before the viability of pregnancy. A multidisciplinary team approach is necessary to manage such situations. Complete excision is necessary because of its association with tissues of malignant potential.

Indications and outcomes of deep anterior lamellar keratoplasty in children.

PURPOSE: To report our experience of deep anterior lamellar keratoplasty (DALK) in children. DESIGN: Retrospective case note review. PARTICIPANTS: Nine patients (13 eyes) aged from 13 weeks to 14 years, 11 months at the Clinical and Academic Department of Ophthalmology, Great Ormond Street Hospital for Children National Health Service (NHS) Trust, London, United Kingdom. METHODS: A study of all pediatric patients undergoing DALK from February 2002 to October 2008 was undertaken. Deep anterior lamellar keratoplasty was attempted in 9 children (13 eyes); the procedure was successful in 11 eyes, and 2 eyes progressed to penetrating keratoplasty (PKP). One eye underwent repeat DALK. Preoperative examination included electrophysiology, ultrasound biomicroscopy (UBM), and slit-lamp biomicroscopy. MAIN OUTCOME MEASURES: Complications and visual acuity at last follow-up. RESULTS: Five patients had mucopolysaccharidoses (MPS), 3 patients had scarring presumed to be infectious, and 1 patient had keratoconus. Because of the failure of follow-up and loose sutures, 1 child with MPS had an epithelial rejection and the operation was repeated successfully. All grafts showed good graft clarity 10 to 80 months after grafting with visual acuities ranging from 0.28 to 1.0 logarithm of the minimum angle of resolution. Two children with nonspecific causes of scarring showed good visual acuities 24 to 51 months post-DALK. Two children who had conversion to PKP were lost to follow-up because they had moved abroad. In 4 of the 5 children with MPS, established techniques of DALK could not be performed because of excessive glycosaminoglycans (GAGs) in the stroma. Ultrasound biomicroscopy was used to guide trephination depth in the first instance. In 1 child with MPS, viscodissection was successfully used. All clinically diagnosed scars were histologically confirmed, and electron microscopy of corneal buttons confirmed the diagnosis in patients with MPS. CONCLUSIONS: Deep anterior lamellar keratoplasty should be considered in children with MPS and partial-thickness scars. In MPS, viscodissection and the "big bubble" technique may not be useful if there are excessive GAGs in the stroma. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.