Asynchronous pineoblastoma is more likely after early diagnosis of retinoblastoma: a meta-analysis

Purpose

To determine the risk of patients with an early diagnosis of heritable retinoblastoma being diagnosed with TRb (or pineoblastoma) asynchronously in a later stage and its effect on screening.

Methods

We updated the search (PubMed and Embase) for published literature as performed by our research group in 2014 and 2019. Trilateral retinoblastoma (TRb) patients were eligible for inclusion if identifiable as unique and the age at which TRb was diagnosed was available. The search yielded 97 new studies. Three new studies and eight new patients were included. Combined with 189 patients from the previous meta‐analysis, the database included 197 patients. The main outcome was the percentage of asynchronous TRb in patients diagnosed before and after preset age thresholds of 6 and 12 months of age at retinoblastoma diagnosis.

Results

Seventy‐nine per cent of patients with pineoblastoma are diagnosed with retinoblastoma before the age of 12 months. However, baseline MRI screening at time of retinoblastoma diagnosis fails to detect the later diagnosed pineal TRb in 89% of patients. We modelled that an additional MRI performed at the age of 29 months picks up 53% of pineoblastomas in an asymptomatic phase. The detection rate increased to 72%, 87% and 92%, respectively, with 2, 3 and 4 additional MRIs.

Conclusions

An MRI of the brain in heritable retinoblastoma before the age of 12 months misses most pineoblastomas, while retinoblastomas are diagnosed most often before the age of 12 months. Optimally timed additional MRI scans of the brain can increase the asymptomatic detection rate of pineoblastoma.

Treatment Outcome of Children with Retinoblastoma in a Tertiary Care Referral Hospital in Indonesia

Background:

Although survival rates for retinoblastoma (RB) are over 95% in high-income countries, its high mortality rate in low and middle-income countries remains a great concern. Few studies investigated treatment outcome and factors contributing to RB survival in these latter settings. Aims of this study are to determine treatment outcome of Indonesian children diagnosed with RB and to explore factors predictive of treatment outcome.

Methods:

This study was a retrospective medical records review combined with an illustrative case report. Children newly diagnosed with RB between January 2011 and December 2016 at a tertiary care referral hospital in Indonesia were included. A home visit was conducted to perform an in-depth interview with a mother of two children affected by RB.

Results:

Of all 61 children with RB, 39% abandoned treatment, 21% died, 20% had progressive or relapsed disease and 20% event-free survival. Progressive or relapsed disease was more common in older (≥ 2 years at diagnosis, 29%) than young (<2 years at diagnosis, 0%) children (P=0.012). Event-free survival estimate at 5 years was higher in young (42%) than older (6%) children (P=0.045). Odds-ratio for event-free survival was 6.9 (95% CI: 1.747 – 27.328, P=0.006) for young versus older children. Other clinical and socio-demographic characteristics had no significant correlation with treatment outcome or event-free survival. The case report elucidated conditions and obstacles that Indonesian families face when their children are diagnosed with RB.

Conclusion:

Survival of children with RB in Indonesia is much lower compared to high-income and many other low and middle-income countries. Abandonment of treatment is the most common cause of treatment failure. Older age at diagnosis is associated with more progressive or relapsed disease and worse survival. Interventions to improve general public and health-care providers’ awareness, early detection and treatment adherence are required.

Clinical value of a screening tool for tumor predisposition syndromes in childhood cancer patients (TuPS): a prospective, observational, multi-center study

Recognizing a tumor predisposition syndrome (TPS) in a child with cancer is of clinical relevance. Earlier we developed a screening tool to increase diagnostic accuracy and clinical efficiency of identifying TPSs in children with cancer. Here we report on the value of this tool in clinical practice. TuPS is a prospective, observational, multi-center study including children newly diagnosed with cancer from 2016 to 2019 in the Netherlands. Children in whom a TPS had been diagnosed before the cancer diagnosis were excluded. The screening tool consists of a checklist, 2D and 3D photographic series and digital assessment of these by a clinical geneticist. If a TPS was suspected, the patient was assessed positive and referred for routine genetic consultation. Primary aim was to assess the clinical value of this new screening tool. Of the 363 included patients, 57% (208/363) were assessed positive. In 15% of patients (32/208), the 2D photographic series with (n = 12) or without (n = 20) 3D photographs were decisive in the positive assessment. In 2% (4/208) of positive assessed patients, a TPS was diagnosed, and in an additional 2% (4/208) a germline variant of uncertain significance was found. Thirty-five negatively assessed patients were evaluated through routine genetic consultation as controls, in none a TPS was detected. Using the screening tool, 57% of the patients were assessed as suspected for having a TPS. No false negative results were identified in the negative control group in the clinical care setting. The observed prevalence of TPS was lower than expected, due to selection bias in the cohort.

Recommendations for Long-Term Follow-up of Adults with Heritable Retinoblastoma

PURPOSE

To generate recommendations for long-term follow-up of adult survivors of heritable retinoblastoma.

DESIGN

We convened a meeting of providers from retinoblastoma centers around the world to review the state of the science and to evaluate the published evidence.

PARTICIPANTS

Retinoblastoma is a rare childhood cancer of the retina. Approximately 40% of retinoblastoma cases are heritable, resulting from a germline mutation in RB1. Dramatic improvements in treatment and supportive care have resulted in a growing adult survivor population. However, survivors of heritable retinoblastoma have a significantly increased risk of subsequent malignant neoplasms, particularly bone and soft tissue sarcomas, uterine leiomyosarcoma, melanomas, and radiotherapy-related central nervous system tumors, which are associated with excess morbidity and mortality. Despite these risks, no surveillance recommendations for this population currently are in place, and surveillance practices vary widely by center.

METHODS

Following the Institute of Medicine procedure for clinical practice guideline development, a PubMed, EMBASE, and Web of Science search was performed, resulting in 139 articles; after abstract and full-text review, 37 articles underwent detailed data abstraction to quantify risk and evidence regarding surveillance, if available. During an in-person meeting, evidence was presented and discussed, resulting in consensus recommendations.

MAIN OUTCOME MEASURES

Diagnosis and mortality from subsequent neoplasm.

RESULTS

Although evidence for risk of subsequent neoplasm, especially sarcoma and melanoma, was significant, evidence supporting routine testing of asymptomatic survivors was not identified. Skin examination for melanoma and prompt evaluation of signs and symptoms of head and neck disease were determined to be prudent.

CONCLUSIONS

This review of the literature confirmed some of the common second cancers in retinoblastoma survivors but found little evidence for a benefit from currently available surveillance for these malignancies. Future research should incorporate international partners, patients, and family members.

Screening for Pineal Trilateral Retinoblastoma Revisited: A Meta-analysis

TOPIC

To determine the age up to which children are at risk of trilateral retinoblastoma (TRb) developing, whether its onset is linked to the age at which intraocular retinoblastomas develop, and the lead time from a detectable pineal TRb to symptoms.

CLINICAL RELEVANCE

Approximately 45% of patients with retinoblastoma-those with a germline RB1 pathogenic variant-are at risk of pineal TRb developing. Early detection and treatment are essential for survival. Current evidence is unclear regarding the usefulness of screening for pineal TRb and, if useful, the age up to which screening should be continued.

METHODS

We conducted a study according to the Meta-analysis of Observational Studies in Epidemiology guidelines for reporting meta-analyses of observational studies. We searched PubMed and Embase between January 1, 1966, and February 27, 2019, for published literature. We considered articles reporting patients with TRb with survival and follow-up data. Inclusion of articles was performed separately and independently by 2 authors, and 2 authors also independently extracted the relevant data. They resolved discrepancies by consensus.

RESULTS

One hundred thirty-eight patients with pineal TRb were included. Of 22 asymptomatic patients, 21 (95%) were diagnosed before the age of 40 months (median, 16 months; interquartile range, 9-29 months). Age at diagnosis of pineal TRb in patients diagnosed with retinoblastoma at 6 months or younger versus older than 6 months were comparable (P = 0.44), suggesting independence between the ages at diagnosis of intraocular retinoblastoma and pineal TRb. The laterality of intraocular retinoblastoma and its treatment were not associated with the age at which pineal TRb was diagnosed. The lead time from asymptomatic to symptomatic pineal TRb was approximately 1 year. By performing a screening magnetic resonance imaging scan every 6 months after the diagnosis of heritable retinoblastoma (median age, 6 months) until 36 months of age, at least 311 and 776 scans would be required to detect 1 case of asymptomatic pineal TRb and to save a single life, respectively.

CONCLUSIONS

Patients with retinoblastoma are at risk of pineal TRb developing for a shorter period than previously assumed, and the age at diagnosis of pineal TRb is independent of the age at diagnosis of retinoblastoma. The GRADE (Grading of Recommendations Assessment, Development and Evaluation) level of evidence for these conclusions remains low.

Feasibility of RetinoQuest: e-health application to facilitate and improve additional care for retinoblastoma survivors

PURPOSE

The current study aimed to evaluate the feasibility of RetinoQuest in clinical practice, from survivors and healthcare professionals' (HCPs) point of view.

METHODS

RetinoQuest is a touch screen computer program to monitor health-related quality of life (HRQoL) of retinoblastoma survivors via patient-reported outcome measures (PROMs) targeting children (4-10 years) as evaluated by their parents (proxy measures), adolescents (11-18 years), and adults. Feasibility was evaluated by the actual time taken to complete the PROMs, acceptability of the time as perceived by the users, the content of PROMs in RetinoQuest, and overall satisfaction with RetinoQuest.

RESULTS

Ninety-six survivors participated: 41 parents of children, 38 adolescents, and 17 adults. Mean time to complete the evaluation form was 7.8 min (median 6.7, range 2.4-24.5), and 90% of the users stated that the time needed to complete PROMs in RetinoQuest was acceptable. The majority of users reported that it was important to answer the questions (88% of the parents, 66% of the adolescents, and 76% of the adult survivors) and that all important issues were covered, e.g., no missing questions (78, 84, and 76%, respectively). Satisfaction rate was high, 7.8 according to parents, 8.1 according to adolescents, and 7.7 for adults.

CONCLUSIONS

RetinoQuest is a feasible e-health application to monitor HRQoL in retinoblastoma survivors in clinical practice.

IMPLICATIONS FOR CANCER SURVIVORS

This tool allows for open and structured communication which can lead to early detection of psychosocial impacts on quality of life and referral of the retinoblastoma survivors.

Validation of a clinical screening instrument for tumour predisposition syndromes in patients with childhood cancer (TuPS): protocol for a prospective, observational, multicentre study

INTRODUCTION

Recognising a tumour predisposition syndrome (TPS) in patients with childhood cancer is of significant clinical relevance, as it affects treatment, prognosis and facilitates genetic counselling. Previous studies revealed that only half of the known TPSs are recognised during standard paediatric cancer care. In current medical practice it is impossible to refer every patient with childhood cancer to a clinical geneticist, due to limited capacity for routine genetic consultation. Therefore, we have developed a screening instrument to identify patients with childhood cancer with a high probability of having a TPS. The aim of this study is to validate the clinical screening instrument for TPS in patients with childhood cancer.

METHODS AND ANALYSIS

This study is a prospective nationwide cohort study including all newly diagnosed patients with childhood cancer in the Netherlands. The screening instrument consists of a checklist, two- and three-dimensional photographic series of the patient. 2 independent clinical geneticists will assess the content of the screening instrument. If a TPS is suspected based on the instrument data and thus further evaluation is indicated, the patient will be invited for full genetic consultation. A negative control group consists of 20% of the patients in whom a TPS is not suspected based on the instrument; they will be randomly invited for full genetic consultation. Primary outcome measurement will be sensitivity of the instrument.

ETHICS AND DISSEMINATION

The Medical Ethical Committee of the Academic Medical Centre stated that the Medical Research Involving Human Subjects Act does not apply to this study and that official approval of this study by the Committee was not required. The results will be offered for publication in peer-reviewed journals and presented at International Conferences on Oncology and Clinical Genetics. The clinical data gathered in this study will be available for all participating centres.

TRIAL REGISTRATION NUMBER

NTR5605.

Long-term audiologic follow-up of carboplatin-treated children with retinoblastoma

BACKGROUND

Children treated for retinoblastoma with carboplatin have an increased risk for ototoxicity. Impaired hearing may have major consequences for these children, because they often suffer from reduced vision. Previous studies have shown limited information on the incidence and severity of carboplatin-induced ototoxicity and the used audiologic methods. The frequency of audiological testing is often limited and the audiologic follow-up time is relatively short.

OBJECTIVE

The aim of this study was to determine the long-term effects of carboplatin ototoxicity in children with retinoblastoma.

MATERIALS AND METHODS

In this retrospective non-randomized single center cohort study, we reviewed audiologic results of 25 patients. Experienced audiologists analyzed the pure-tone audiograms.

RESULTS

All patients had normal hearing prior to therapy and had a mean age of 11 months at first carboplatin administration. The mean audiologic follow-up was 12.0 years with a median of 11.6 (IQR 4.8) years. Three patients were excluded: two passed away and one could not participate in the audiologic tests. One of the 22 included patients developed sustained low-grade bilateral high-frequency hearing loss between 2 and 7 years after the last carboplatin dose. In one patient it was not possible to make a reliable conclusion due to a conductive hearing loss component. Twenty patients had normal hearing.

CONCLUSIONS

We observed no clear effect between carboplatin administration in young children and clinical significant ototoxicity in the long term. One child showed low-grade bilateral high-frequency hearing loss.

The Incidence of Trilateral Retinoblastoma: A Systematic Review and Meta-Analysis

PURPOSE

To estimate the incidence of trilateral retinoblastoma in patients with retinoblastoma.

DESIGN

Systematic review and meta-analysis.

METHODS

We searched Medline and Embase for scientific literature published between January 1966 and July 2015 that assessed trilateral retinoblastoma incidence. We used a random-effects model for the statistical analyses.

RESULTS

We included 23 retinoblastoma cohorts from 26 studies. For patients with bilateral retinoblastoma the unadjusted chance of developing trilateral retinoblastoma across all cohorts was 5.3% (95% confidence interval [CI]: 3.3%-7.7%); the chance of pineal trilateral retinoblastoma was 4.2% (95% CI: 2.6%-6.2%) and the chance of nonpineal trilateral retinoblastoma was 0.8% (95% CI: 0.4%-1.3%). In patients with hereditary retinoblastoma (all bilateral cases, and the unilateral cases with a family history or germline RB1 mutation) we found a trilateral retinoblastoma incidence of 4.1% (95% CI: 1.9%-7.1%) and a pineal trilateral retinoblastoma incidence of 3.7% (95% CI: 1.8%-6.2%). To reduce the risk of overestimation bias we restricted analysis to retinoblastoma cohorts with a minimum size of 100 patients, resulting in adjusted incidences of 3.8% (95% CI: 2.4%-5.4%), 2.9% (95% CI: 1.9%-4.2%), and 0.7% (95% CI: 0.3%-1.2%) for any, pineal, and nonpineal trilateral retinoblastoma, respectively, among patients with bilateral retinoblastoma. Among hereditary retinoblastoma we found an adjusted trilateral retinoblastoma incidence of 3.5% (95% CI: 1.2%-6.7%) and a pineal trilateral retinoblastoma incidence of 3.2% (95% CI: 1.4%-5.6%).

CONCLUSION

The estimated incidence of trilateral retinoblastoma is lower than what is reported in previous literature, especially after exclusion of small cohorts that were subject to overestimation bias in this context.

Trilateral retinoblastoma: a systematic review and meta-analysis

BACKGROUND

About 5% of children with retinoblastoma from germline mutation of the RB1 gene are at risk of developing trilateral retinoblastoma--intraocular retinoblastoma combined with a histologically similar brain tumour, most commonly in the pineal gland. We aimed to provide a systematic overview of published data for trilateral retinoblastoma, and to analyse how survival has changed.

METHODS

We searched Medline and Embase for scientific literature published between Jan 1, 1966, and April 14, 2014, that assessed trilateral retinoblastoma cases. We undertook a meta-analysis of survival with the Kaplan-Meier method and Cox proportional hazards regression, stratified on the basis of the original study, to account for between-study heterogeneity.

FINDINGS

We included 90 studies, with 174 patients with trilateral retinoblastoma. 5-year survival after pineal trilateral retinoblastoma increased from 6% (95% CI 2-15) in patients diagnosed before 1995, to 44% (26-61; p<0·0001) in those diagnosed from 1995 onwards. Before 1995, no patients with non-pineal trilateral retinoblastoma survived, but from 1995 onwards, 5-year survival was 57% (30-77; p=0·035). Hazard ratios (HR) adjusted for the presence of leptomeningeal metastases and trilateral retinoblastoma location, suggested that both conventional (HR 0·059, 95% CI 0·016-0·226; p<0·0001) and high-dose chemotherapy with stem-cell rescue (0·013, 0·002-0·064; p<0·0001) most strongly contributed to this improvement. Absence of leptomeningeal metastases (HR 2·13, 95% CI 0·98-4·60; p=0·055) were associated with improved survival. Non-pineal trilateral retinoblastomas were larger than pineal tumours (median 30 mm [range 6-100] vs 22 mm [7-60]; p=0·012), but both had similar outcomes since 1995.

INTERPRETATION

Our results suggest that improvements in overall survival are attributable to improved chemotherapy regimens and early detection of pineal trilateral retinoblastoma. As such, successful treatment of trilateral retinoblastoma should include screening at least at the time of retinoblastoma diagnosis and chemotherapy, which would preferably be a high-dose regimen with autologous stem-cell rescue.

FUNDING

None.

High resolution SNP array profiling identifies variability in retinoblastoma genome stability

Both hereditary and nonhereditary retinoblastoma (Rb) are commonly initiated by loss of both copies of the retinoblastoma tumor suppressor gene (RB1), while additional genomic changes are required for tumor initiation and progression. Our aim was to determine whether there is genomic heterogeneity between different clinical Rb subtypes. Therefore, 21 Rb tumors from 11 hereditary patients and 10 nonhereditary Rb patients were analyzed using high-resolution single nucleotide polymorphism (SNP) arrays and gene losses and gains were validated with Multiplex Ligation-dependent Probe Amplification. In these tumors only a few focal aberrations were detected. The most frequent was a focal gain on chromosome 2p24.3, the minimal region of gain encompassing the oncogene MYCN. The genes BAZ1A, OTX2, FUT8, and AKT1 were detected in four focal regions on chromosome 14 in one nonhereditary Rb. There was a large difference in number of copy number aberrations between tumors. A subset of nonhereditary Rbs turned out to be the most genomic unstable, while especially very young patients with hereditary Rb display stable genomes. Established Rb copy number aberrations, including gain of chromosome arm 1q and loss of chromosome arm 16q, turned out to be preferentially associated with the nonhereditary Rbs with later age of diagnosis. In contrast, copy number neutral loss of heterozygosity was detected mainly on chromosome 13, where RB1 resides, irrespective of hereditary status or age. Focal amplifications and deletions and copy number neutral loss of heterozygosity besides chromosome 13 appear to be rare events in retinoblastoma.

Incidence of retinoblastoma in Dutch children conceived by IVF: an expanded study

BACKGROUND

In 2003, we reported an increased risk of retinoblastoma in children conceived by IVF between 1995 and 2002. However, population-based studies among children conceived by IVF did not find an elevated risk of retinoblastoma.

METHODS

From nationwide estimates of numbers of live births conceived by IVF (n = 40 330), we estimated the expected numbers of patients with retinoblastoma conceived by IVF in the period 1995-2007. The observed number of retinoblastoma diagnoses in children conceived by IVF was obtained by questionnaires sent to the parents of children with retinoblastoma diagnosed between 1995 and 2005. For non-responders and patients diagnosed after 2005, information was available through the medical files, in which information on fertility treatment has been routinely recorded since 2000. The relative risk (RR) of retinoblastoma among children conceived by IVF was calculated for the total study period (1995-2007) and for the expanded study period (2002-2007).

RESULTS

Of all eligible patients with retinoblastoma (n = 162) diagnosed in the period 1995-2007, seven were conceived by IVF. In the total study period (1995-2007) the risk was significantly elevated [RR = 2.54, 95% confidence interval (CI) = 1.02-5.23]. In the expanded study period (2002-2007), no significantly elevated risk (RR = 1.29, 95% CI = 0.16-4.66) was found.

CONCLUSIONS

We found a significantly increased risk of retinoblastoma in children conceived by IVF in the total study period 1995-2007. However, this increased risk was mostly based on the much stronger risk increase observed previously, for 1995-2002. Caution and awareness on the one hand and avoiding unnecessary worries on the other hand are important at this stage of our knowledge.

Postoperative hemicerebellar inflammation mimicking recurrent tumor after resection of a medulloblastoma. Case report

The authors present the case of a 4-year-old boy in whom a medulloblastoma in the left cerebellar hemisphere was successfully resected with no signs of residual tumor on the postoperative magnetic resonance (MR) images. A second MR imaging study performed 1 month after surgery demonstrated an extensive, contrast-enhancing lesion in the left cerebellar hemisphere, which simulated massive recurrent tumor, and repeated surgery was considered. A third postoperative MR imaging study, performed for evaluation of the craniospinal axis 10 days after the second postoperative study, still showed some contrast enhancement in the left cerebellar hemisphere, but the lesion had almost disappeared. Postoperative hemicerebellar inflammation seemed to be the most likely explanation. This case illustrates that early postoperative inflammation can mimic recurrent tumor on MR images obtained after resection of a medulloblastoma and caution should be taken in interpreting such images. Clinical history, neurological examination, laboratory findings, and repeated MR imaging studies can be helpful in evaluating the patient accurately.

Beta-trace protein is not superior to cystatin C for the estimation of GFR in patients receiving corticosteroids

OBJECTIVES

Comparison of the effect of corticosteroid therapy on the diagnostic performance of cystatin C (Cys) and beta-trace protein (bTP), two endogenous markers of GFR.

DESIGN AND METHODS

Out of a total of 193 pediatric inulin clearance studies, a random sample of 85 steroid-free studies served to establish GFR prediction equations (eGFR), which were used to compare the remaining 76 steroid-free and 32 steroid-positive studies (median prednisone dose 33.0 mg m(-2) day(-1)).

RESULTS

We found a positive relationship between prednisone dose and eGFR(betaTP) (b=0.414, p=0.0002) and a negative relationship with eGFR(cys) (b=-0.208, p=0.0091). Only Cys independently predicted GFR below 90 mL min(-1) 1.73 m(-2), both in steroid-positives (b=6.260, p=0.010) and steroid-negatives (b=6.845, p=0.012). Glucocorticoid therapy did not affect the accuracy in estimating GFR within 30% of measured GFR for Cys, while accuracy was lower with bTP (65.6% vs. 81.6%, p=0.08).

CONCLUSION

Glucocorticoids have less impact on the diagnostic accuracy of Cys than bTP.

Urinary NOx:creatinine ratios during gluten challenge in children with celiac disease

OBJECTIVES

Celiac disease is a gluten-induced small bowel enteropathy. Inflammation is known to be associated with enhanced nitric oxide (NO) production. An increase in urinary nitrate and nitrite (NOx) reflects increased NO production. The urinary NOx:creatinine ratio can be used as an indicator of the endogenous NO production. The aim of the study was to determine whether the urinary NOx:creatinine ratio of celiac disease patients increases during gluten challenge.

METHODS

The authors studied 20 patients with unconfirmed celiac disease who had been following a gluten-free diet for at least 1 year. These patients underwent an 80-day gluten challenge. Urinary samples were obtained before and 10, 20, 40, and 80 days after starting the gluten challenge. The Griess reagent method was used for measuring urinary NOx.

RESULTS

Gluten challenge confirmed the diagnosis of celiac disease in 15 of 20 patients. The NOx:creatinine ratios (mmol:mmol) of the biopsy-confirmed celiac disease patients were significantly higher than those of the unconfirmed celiac disease patients (0.67 vs. 0.17 on day 10; 0.78 vs. 0.15 on day 20; 0.85 vs. 0.25 on day 40; and 0.85 vs. 0.17 on day 80).

CONCLUSIONS

Gluten challenge resulted in an increased urinary NOx:creatinine ratio in patients with biopsy-confirmed celiac disease. The NOx:creatinine ratio could be useful for the serial evaluation of disease activity.

Leydig cell hypoplasia: cases with new mutations, new polymorphisms and cases without mutations in the luteinizing hormone receptor gene

BACKGROUND

Defective male sex differentiation in patients with hypoplasia of Leydig cells (LCH) is caused by deficient LH receptor signal transduction. To further investigate the variety of LH receptor gene mutations present in LCH patients and their influence on the phenotype, we examined 10 nonrelated patients with the clinical presentation of LCH.

PATIENTS AND METHODS

Ten patients with a clinical phenotype of LCH were analysed for mutations in the complete coding region of the LH receptor gene. Exons 1-10 and two overlapping fragments of exon 11 of the LH receptor gene including all intron-exon boundaries were amplified by polymerase chain reaction and sequenced. To screen for frequencies of DNA changes, mutation analysis was performed on 45-59 healthy persons using denaturation high-performance liquid chromatography.

RESULTS

Six new DNA alterations were identified. Three of them appear to be new polymorphisms. A G to C change at the 28th nucleotide of intron 1 on one allele and a heterozygous CGA to CAA transition at codon 124 (R124Q) were found. Both findings in these two patients are polymorphisms that occur with a frequency of 17% and 1.7%, respectively. A silent heterozygous CTA to TTA change at codon 204 was identified. In a patient with micropenis, the analysis revealed a homozygous missense mutation at codon 625 (I625K). As reported previously, this alteration significantly impaired signal transduction and explains the partial phenotype. Finally, in one compound heterozygous patient, two different mutations were discovered. At the polymorphic site in exon 1, a 27-bp insertion (CTG)2 AAG (CTG)5 CAG and a premature stop codon in the transmembrane segment 4 (W491*) were found. Both mutations disrupt signal transduction and explain the complete phenotype of this patient. In five patients, no DNA alterations could be identified.

CONCLUSIONS

Three mutations (33 bp insertion in exon 1; W491* and I625K) were identified that explain the phenotype in two patients. In addition, most of the patients with the clinical phenotype of LCH did not have causative mutations, suggesting that changes in other regions of the LH receptor gene, such as the large introns or the promoter region, may be responsible for the majority of cases. Alternatively, the displayed phenotype may be the result of other genetic defects. Our work further underscores the importance of thorough clinical analysis of patients before molecular analysis of a particular gene is performed.