Limb reduction defects in South America

Prevalence pattern, phenotypic manifestation, and descriptive genetics of congenital limb deficiencies in Pakistan

BACKGROUND

Congenital limb deficiency (CLD) is a group of very rare disorders characterized by substantial hypoplasia or the complete absence of 1 or more bones of limbs. Congenital limb deficiency has a significant physical, clinical, and psychological burden on the affected individuals and their families. This cross-sectional study aimed to describe the prevalence pattern, phenotypic manifestations, and biodemographic factors associated with CLD in a cohort assembled from the Pakistani population from the Northwestern region.

METHODS

Through a prospective cross-sectional study, 141 individuals having 166 limbs with CLD were recruited during 2017-2021.

RESULTS

There were 77 (55%) individuals with transverse defects, 61 (43%) with longitudinal defects, and 3 (2%) with Intercalary defects. Among the patients with transverse defects, 52 had terminal amputations and 25 had symbrachydactyly. Among the longitudinal defects, thumb aplasia/hypoplasia was the most common presentation (20 patients), followed by oligodactyly (18), and radial hemimelia (18). Eighty six percent had upper-limb deficiencies, 83% had unilateral deficiencies, and 92% were sporadic in nature. The parental consanguinity was observed in 33% individuals, and 79% cases had an isolated presentation which may be indicative of the substantial role of nongenetic factors in the etiology of CLD.

CONCLUSIONS

This study demonstrates marked heterogeneity in CLD subtypes in the involvement of limbs and associated variables. There is a need to establish a national registry for CLD, molecular genetic diagnosis, and multidisciplinary medical and social rehabilitation services for these individuals.

Intellectual Characteristics in Children With Congenital Unilateral Upper Limb Deficiencies

Introduction Some children with motor disabilities show low cognitive levels. However, the influence of motor disabilities on children's intelligence remains to be fully elucidated. This study aimed to clarify the intellectual characteristics of children with upper limb deficiencies and the influence of upper limb impairments on intelligence. Methods The participants were 10 children from four to six years of age with congenital unilateral transradial or transcarpal limb deficiencies who received prosthetic interventions. The children's intelligence and adaptive behaviors, including motor skills, were examined using the Wechsler Preschool and Primary Scale of Intelligence and the Vineland Adaptive Behavior Scale, respectively. Results There were no significant characteristics or discrepancies in cognitive level in children with upper limb deficiencies. The Adaptive Behavior Composite Score of the Vineland Adaptive Behavior Scale was significantly positively correlated with the Full-Scale Intelligence Quotient of the Wechsler Preschool and Primary Scale of Intelligence. Conclusions The children with congenital limb deficiencies showed average cognitive levels. Expansion of adaptive behaviors, including appropriate complementation of disabilities, may promote intellectual development in children with motor disabilities.

Amelia and phocomelia in Finland: Characteristics and prevalences in a nationwide population‐based study

BACKGROUND

Amelia and phocomelia represent severe limb reduction defects. Specific epidemiologic data on these defects are scarce. We conducted a descriptive analysis of prevalence data in Finland during 1993-2008 to clarify the epidemiology nationwide in a population-based register study. We hypothesized that increasing maternal age would affect the total prevalence of each disorder.

MATERIALS AND METHODS

We collected information on all fetuses and infants affected by amelia and phocomelia during 1993-2008 from the National Register of Congenital Malformations in Finland. The clinical, laboratory, autopsy, and imaging data were re-evaluated where available for all cases found.

RESULTS

A total of 23 amelia and 7 phocomelia patients were identified. Thalidomide was not an etiological factor in any of the cases. The total prevalence of amelia was 2.43 per 100,000 births. The live birth prevalence was 0.63 per 100,000 live births. The total prevalence of phocomelia was 0.74 per 100,000 births, and the live birth prevalence was 0.53 per 100,000 live births. Infant mortality in amelia and phocomelia was 67% and 60%, respectively.

CONCLUSIONS

Infant mortality is high among amelia and phocomelia. Most cases had other major associated anomalies, but syndromic amelia cases were rare. Total prevalences were higher than previously reported and showed an increase in prevalence toward the end of the study period. The percentage of elective terminations of pregnancy for these disorders is high. While isolated cases are rare, they most likely present a better prognosis. Thus, correct diagnosis is essential in counseling for possible elective termination.

Relationship between degree of disability, usefulness of assistive devices, and daily use duration: an investigation in children with congenital upper limb deficiencies who use upper limb prostheses

Upper limb prostheses can help children with congenital upper limb deficiencies (ULDs) perform activities of daily living. Although the degree of disability and prosthesis usefulness may be related to becoming accustomed to wearing a prosthesis, these relationships have not been confirmed. This study was aimed at investigating the relationship between motor function, the usefulness of prostheses in everyday activities, and daily duration of prosthesis use in children with congenital ULDs. Eleven children with congenital transcarpal or transradial ULDs and their caregivers participated in this study. The caregivers were asked to complete a questionnaire concerning their children's everyday activities and the daily duration of prosthesis wearing. The adaptive behavior scale was used to measure motor function prior to intervention. Correlations analyses revealed no significant correlation between the children's adaptive behavior, including motor skills before intervention, and daily duration of prosthesis wearing, but revealed a positive correlation between the number of activities that the children performed more effectively with their prostheses and the daily use duration. To ensure that children with congenital ULDs become accustomed to wearing their prostheses, the prostheses should meet the requirements of everyday activities.

Treatment approaches for congenital transverse limb deficiency: Data analysis from an epidemiological national survey in Japan

BACKGROUND

Congenital limb deficiency is a rare anomaly that impairs limb function. Transverse deficiency accounts for approximately half of congenital limb deficiency cases. In Japan, there have been no detailed data of clinical features, especially treatment approaches, of this disorder. The present study aimed to investigate the status of treatment approaches of congenital transverse limb deficiency in Japan.

METHODS

From the national epidemiological survey of congenital limb deficiency undertaken in Japan in 2016, all the data of 200 patients with congenital transverse limb deficiencies were extracted. These data were analysed to reveal the treatment approaches of congenital transverse limb deficiency and its basic clinical features.

RESULTS

Surgical treatments and prosthetic or orthotic intervention had been implemented or planned for about one-quarter of patients, respectively. In the upper limb deficiencies, prosthetic or orthotic intervention was likely chosen in cases of deficiency at the metacarpal or proximal to metacarpal level. Surgical treatment was chosen only in cases of deficiency at the carpal or distal to carpal level. Although the number of patients with transverse lower limb deficiencies was small, prosthetic or orthotic intervention was likely chosen in proximal deficiencies, and surgical treatment was likely chosen in distal deficiencies.

CONCLUSIONS

Herein, we revealed the status of treatment approaches for congenital transverse limb deficiency in Japan. Approximately half of the patients had no history of-and no plans for-surgical, prosthetic, or orthotic interventions. Further treatment advances may enable patients with congenital limb deficiencies to increase their participation in daily activities.

STUDY DESIGN

Cross-sectional survey.

Rehabilitation Approach for a Child with Cerebral Palsy and Upper Limb Deficiency

Background

Congenital limb deficiency is a rare and intractable anomaly of the limbs; however, prostheses can partially complement the motor function and appearance of the missing limbs. The first prosthesis is usually prescribed for children with upper limb deficiencies at approximately 6-8 months of age. In affected children with additional problems associated with motor function, such as limb paralysis, the age for initiating prosthetic therapy and the benefit of prostheses in promoting and expanding their motor function and activities is unknown.

Case

In this case presentation, we describe a 25-month-old boy with cerebral palsy and left unilateral congenital upper limb deficiency caused by congenital constriction band syndrome. The patient could stand with assistance and crawl on his hands and knees. However, he was unable to walk with assistance or to stand on his own. A forearm prosthesis with a passive hand was prescribed and issued, and rehabilitation therapy for wearing and using the prosthesis was performed. At 34 months of age, the patient was able to walk forward using a walker with the prosthesis. Without the prosthesis, he still could not walk using a walker. The upper limb prosthesis also improved other movements such as sitting, standing, and tasks performed on a desk or on the floor.

Discussion

The prosthesis was apparently effective in improving motor function. Prosthesis prescription should be considered at an appropriate and early age considering individual developmental stages and needs, regardless of the existence of additional problems associated with motor function.

Effect of prostheses on children with congenital upper limb deficiencies

BACKGROUND

Individual weaknesses in motor skills are a characteristic of children with congenital upper limb deficiencies. These weaknesses increase with age. In Japan, however, prosthetic prescription and subsequent rehabilitation approaches for children with upper limb deficiencies are insufficient and often delayed. This study aimed to elucidate whether rehabilitation approaches, including prostheses prescription and occupational therapy, improve these children's adaptive behaviors, especially their motor skills.

METHODS

The study included nine children, aged 0-6 years, with unilateral transradial or transcarpal upper limb deficiencies. We measured their adaptive behaviors and motor skills at the beginning of prosthetic therapy and after 1.5 years, using the Vineland Adaptive Behavior Scales - Second Edition.

RESULTS

The score for the motor skills domain was significantly lower than the median score of the domains at the beginning of prosthetic therapy. The motor skill weaknesses significantly improved after 1.5 years of prosthetic therapy.

CONCLUSIONS

Although children with congenital upper limb deficiencies have individual weaknesses in their motor skill behavior, it was shown that these weaknesses can be improved through rehabilitation approaches, including occupational and prosthetic therapies. Issuing the appropriate prostheses and implementing the appropriate training to use the prostheses for congenital upper limb deficiencies are reasonable and meaningful interventions to improve quality of life.

Congenital limb reduction defects in 1.6 million births in Argentina

The objectives of this study were to describe the birth prevalence of limb reduction defects (LRD) in Argentina, their clinical features, and to review the literature on this topic. The data source was the National Network of Congenital Anomalies of Argentina, a surveillance system that has been operative since 2009. Data were collected from November 1, 2009 to December 31, 2016. 1,663,610 births and 702 affected patients were registered during this period. The prevalence of LRD was 4.22/10,000 births (CI 95%: 3.93-4.54). In 15,094 stillbirths, prevalence was 30.80/10,000 (CI 95%: 22.31-40.65). Perinatal mortality (stillbirths plus early neonatal deaths) was 24.6%, mostly explained by postnatal deaths. LRD were classified according to different variables, including Gold's anatomic classification. Then, 41.0% of patients had transverse terminal defects and 50.2% had longitudinal defects. We found multiple and syndromic clinical presentation to be associated with both preaxial LRD and lethality. The prevalence of LRD was lower and perinatal mortality was higher in our study compared to that of previously published studies. Because there is heterogeneity in the inclusion and exclusion criteria among publications, a greater effort should be made in order to include similar populations and to use a unified anatomic classification and nomenclature.

Identifying priorities and developing strategies for building capacity in amputation research in Canada

BACKGROUND

Compared to other patient population groups, the field of amputation research in Canada lacks cohesion largely due to limited funding sources, lack of connection among research scientists, and loose ties among geographically dispersed healthcare centres, research institutes and advocacy groups. As a result, advances in clinical care are hampered and ultimately negatively influence outcomes of persons living with limb loss.

OBJECTIVE

To stimulate a national strategy on advancing amputation research in Canada, a consensus-workshop was organized with an expert panel of stakeholders to identify key research priorities and potential strategies to build researcher and funding capacity in the field.

METHODS

A modified Delphi approach was used to gain consensus on identifying and selecting an initial set of priorities for building research capacity in the field of amputation. This included an anonymous pre-meeting survey (N = 31 respondents) followed by an in-person consensus-workshop meeting that hosted 38 stakeholders (researchers, physiatrists, surgeons, prosthetists, occupational and physical therapists, community advocates, and people with limb loss).

RESULTS

The top three identified research priorities were: (1) developing a national dataset; (2) obtaining health economic data to illustrate the burden of amputation to the healthcare system and to patients; and (3) improving strategies related to outcome measurement in patients with limb loss (e.g. identifying, validating, and/or developing outcome measures). Strategies for moving these priorities into action were also developed.

CONCLUSIONS

The consensus-workshop provided an initial roadmap for limb loss research in Canada, and the event served as an important catalyst for stakeholders to initiate collaborations for moving identified priorities into action. Given the increasing number of people undergoing an amputation, there needs to be a stronger Canadian collaborative approach to generate the necessary research to enhance evidence-based clinical care and policy decision-making.IMPLICATIONS FOR REHABILITATIONLimb loss is a growing concern across North America, with lower-extremity amputations occurring due to complications arising from diabetes being a major cause.To advance knowledge about limb loss and to improve clinical care for this population, stronger connections are needed across the continuum of care (acute, rehabilitation, community) and across sectors (clinical, advocacy, industry and research).There are new surgical techniques, technologies, and rehabilitation approaches being explored to improve the health, mobility and community participation of people with limb loss, but further research evidence is needed to demonstrate efficacy and to better integrate them into standard clinical care.

Body knowledge in children with congenital lower limb deficiency

BACKGROUND

In order to effectively improve motor function, a sound understanding of one's body - for example, relative spatial position, relationships, names and functions of body parts - is essential. The aim of this study was to explore how children with congenital lower limb deficiency (LLD) perceive their bodies, particularly their legs.

METHODS

Six children with congenital LLD and 14 controls, aged 5-12 years, were recruited for this study. They drew self-portraits and answered questions about names of body parts. These body part-related questions consisted of a production test, in which an examiner pointed to body parts on each child and asked the child to name them, and a comprehension test, in which the examiner mentioned body parts and asked the child to point to them on their own body.

RESULTS

No differences were found between the self-portraits of children with LLD and those of the control children. In the verbal tests, children with LLD responded correctly at lower rates to questions on body trunk, upper limbs, arms, hands and feet than the control children.

CONCLUSION

Children with LLD have diminished lexical-semantic body knowledge of the upper limbs and feet compared with children without LLD.

Congenital limb deficiency in Japan: a cross-sectional nationwide survey on its epidemiology

Background

Congenital limb deficiency is a rare and intractable disease, which impairs both function and appearance of the limbs. To establish adequate medical care, it is necessary to reveal the actual conditions and problems associated with this disease. However, there have been no extensive epidemiological surveys in Japan addressing this disease. This is the first nationwide epidemiological survey of congenital limb deficiency in this country.

Methods

With the cooperation of epidemiology experts, we performed a two-stage nationwide survey to estimate the number of patients with congenital limb deficiency and reveal basic patient features. We targeted orthopaedic surgery, paediatric, and plastic surgery departments. Hospitals were categorized according to the institution type and the number of hospital beds; hospitals were randomly selected from these categories. We selected 2283 departments from a total 7825 departments throughout Japan. In this study, we defined congenital limb deficiency as partial or total absence of the limbs, proximal to the proximal interphalangeal joint of the fingers/lesser toes or interphalangeal joint of the thumb/great toe. We distributed the first survey querying the number of initial patient visits from January 2014 to December 2015. Targets of the second survey were departments that reported one or more initial patient visits in the first survey.

Results

In the first survey, 1767 departments responded (response rate: 77.4%). Among them, 161 departments reported one or more initial patient visits. We conducted the second survey among these 161 departments, of which 96 departments responded (response rate: 59.6%). The estimated number of initial visits by patients with congenital limb deficiency was 417 (95% confidence interval: 339–495) per year in 2014 and 2015. The estimated prevalence of congenital limb deficiency in Japan was 4.15 (95% confidence interval: 3.37–4.93) per 10,000 live births. The sex ratio was 1.40. Upper limbs were more affected than lower limbs.

Conclusions

We revealed the estimated number of initial patient visits per year and birth prevalence of congenital limb deficiency in Japan. Our results will contribute to establishing the disease concept and grades of severity of congenital limb deficiency.

Electronic supplementary material

The online version of this article (10.1186/s12891-018-2195-3) contains supplementary material, which is available to authorized users.

Maternal periconceptional alcohol consumption and congenital limb deficiencies

BACKGROUND

Women of childbearing age report high rates of alcohol consumption, which may result in alcohol exposure during early pregnancy. Epidemiological research on congenital limb deficiencies (LDs) and periconceptional exposure to alcohol is inconclusive.

METHODS

Data from the National Birth Defects Prevention Study (NBDPS) were examined for associations between LDs and patterns of maternal periconceptional (1 month before conception through the first trimester) alcohol consumption among LD case (n = 906) and unaffected control (n = 8352) pregnancies with expected delivery dates from 10/1997 through 12/2007. Adjusted odds ratios (aORs) and 95% confidence intervals were estimated from unconditional logistic regression analysis for all LDs combined, specific LD subtypes (preaxial/terminal transverse), and LD anatomic groups (upper/lower limbs); interactions with folic acid (FA) supplementation were tested.

RESULTS

When compared with nondrinkers, inverse associations were found between all LDs combined, preaxial, and upper LDs and any reported periconceptional alcohol consumption (aORs ranged from 0.56-0.83), drinking without binging (aORs: 0.53-0.75), and binge drinking (≥4 drinks/occasion) (aORs: 0.64-0.94); however, none of the binge drinking aORs were statistically significant. Stratification by alcohol type showed inverse associations between all LDs combined, preaxial, transverse, and upper and lower LDs for drinking without binging of wine only (aORs: 0.39-0.67) and between all LDs combined and upper LDs for drinking without binging of combinations of alcohol (aORs: 0.63-0.87). FA did not modify observed associations.

CONCLUSION

Maternal periconceptional alcohol consumption did not emerge as a teratogen for selected LDs in the NBDPS. Future studies should evaluate additional rare LDs among more highly exposed populations.

Phocomelia: a worldwide descriptive epidemiologic study in a large series of cases from the International Clearinghouse for Birth Defects Surveillance and Research, and overview of the literature

Epidemiologic data on phocomelia are scarce. This study presents an epidemiologic analysis of the largest series of phocomelia cases known to date. Data were provided by 19 birth defect surveillance programs, all members of the International Clearinghouse for Birth Defects Surveillance and Research. Depending on the program, data corresponded to a period from 1968 through 2006. A total of 22,740,933 live births, stillbirths and, for some programs, elective terminations of pregnancy for fetal anomaly (ETOPFA) were monitored. After a detailed review of clinical data, only true phocomelia cases were included. Descriptive data are presented and additional analyses compared isolated cases with those with multiple congenital anomalies (MCA), excluding syndromes. We also briefly compared congenital anomalies associated with nonsyndromic phocomelia with those presented with amelia, another rare severe congenital limb defect. A total of 141 phocomelia cases registered gave an overall total prevalence of 0.62 per 100,000 births (95% confidence interval: 0.52-0.73). Three programs (Australia Victoria, South America ECLAMC, Italy North East) had significantly different prevalence estimates. Most cases (53.2%) had isolated phocomelia, while 9.9% had syndromes. Most nonsyndromic cases were monomelic (55.9%), with an excess of left (64.9%) and upper limb (64.9%) involvement. Most nonsyndromic cases (66.9%) were live births; most isolated cases (57.9%) weighed more than 2,499 g; most MCA (60.7%) weighed less than 2,500 g, and were more likely stillbirths (30.8%) or ETOPFA (15.4%) than isolated cases. The most common associated defects were musculoskeletal, cardiac, and intestinal. Epidemiological differences between phocomelia and amelia highlighted possible differences in their causes.

Amelia: a multi-center descriptive epidemiologic study in a large dataset from the International Clearinghouse for Birth Defects Surveillance and Research, and overview of the literature

This study describes the epidemiology of congenital amelia (absence of limb/s), using the largest series of cases known to date. Data were gathered by 20 surveillance programs on congenital anomalies, all International Clearinghouse for Birth Defects Surveillance and Research members, from all continents but Africa, from 1968 to 2006, depending on the program. Reported clinical information on cases was thoroughly reviewed to identify those strictly meeting the definition of amelia. Those with amniotic bands or limb-body wall complex were excluded. The primary epidemiological analyses focused on isolated cases and those with multiple congenital anomalies (MCA). A total of 326 amelia cases were ascertained among 23,110,591 live births, stillbirths and (for some programs) elective terminations of pregnancy for fetal anomalies. The overall total prevalence was 1.41 per 100,000 (95% confidence interval: 1.26-1.57). Only China Beijing and Mexico RYVEMCE had total prevalences, which were significantly higher than this overall total prevalence. Some under-registration could influence the total prevalence in some programs. Liveborn cases represented 54.6% of total. Among monomelic cases (representing 65.2% of nonsyndromic amelia cases), both sides were equally involved, and the upper limbs (53.9%) were slightly more frequently affected. One of the most interesting findings was a higher prevalence of amelia among offspring of mothers younger than 20 years. Sixty-nine percent of the cases had MCA or syndromes. The most frequent defects associated with amelia were other types of musculoskeletal defects, intestinal, some renal and genital defects, oral clefts, defects of cardiac septa, and anencephaly.

Associated malformations in patients with limb reduction deficiencies

Infants with limb reduction deficiencies (LRD) often have other associated congenital malformations. The purpose of this investigation was to assess the prevalence and the types of associated malformations in a defined population. This study included special strengths: each affected child was examined by a geneticist, all elective terminations were ascertained, and the surveillance for malformations was continued until 1 year of age. The associated malformations in infants with LRD were collected in all livebirths, stillbirths and terminations of pregnancy during 25 years in 347,810 consecutive births in the area covered by our population based registry of congenital malformations. Of the 271 LRD infants born during this period, representing a prevalence of 7.8 per 10,000, 57.9% had associated malformations. There were 17(6.3%) patients with chromosomal abnormalities including 10 trisomies 18, and 62 (22.9%) nonchromosomal recognized dysmorphic conditions. There were no predominant recognized dysmorphic conditions, but VA(C)TER(L) association. However numerous recognized dysmorphic conditions were registered including Poland, ectrodactyly-ectodermal dysplasia-clefting, oral-facial-digital, Klippel-Trenaunay-Weber, oculo-auriculo-vertebral defect spectrum, CHARGE, Townes-Brocks, Moebius, Du Pan, Smith-Lemli-Opitz, hypoglossia-hypodactyly, amniotic band, De Lange, Rubinstein-Taybi, Fanconi, radius aplasia- thrombocytopenia, Roberts, Holt-Oram, and fetal diethylstilbestrol. Seventy eight (28.8%) of the patients were multiply, non-syndromic, non chromosomal malformed infants (MCA). Malformations in the cardiac system, in the genital system, and in the central nervous system were the most common other malformations, 11.4%, 9.4%, and 7.7% of the associated malformations, respectively, followed by malformations in the renal system (4.8%), and in the digestive system (4.6%). Prenatal diagnosis was performed in 48.4% of dysmorphic syndromes with LRD. The overall prevalence of associated malformations, which was more than one in two infants, emphasizes the need for a thorough investigation of infants with LRD.A routine screening for other malformations especially cardiovascular system, urogenital system, central nervous system, and digestive system may be considered in infants and in fetuses with LRD.

Transverse limb reduction and intrauterine device: Case report and review of the literature

BACKGROUND

Pregnancies with an intrauterine device (IUD) in situ are associated with increased maternal and foetal morbidity and mortality. No proven teratogenetic effects have been attributed to IUDs.

CASE

A 29-year-old-woman conceived with an IUD in place. The device was removed at 7 weeks' gestation. Her level 2 sonogram at 25 weeks' gestation revealed transverse limb reduction of the foetal right forearm. She gave birth at term to a female infant with reduction of the right forearm. The rest of the physical examination, imaging and laboratory tests, including serology and karyotype were normal.

CONCLUSION

We present a rare case of transverse limb reduction defect associated with the presence of an IUD at the time of conception. The device had been removed in the first trimester of the pregnancy. Data from the literature are reviewed.

Clinical and epidemiological findings in patients with central ray deficiency: Split hand foot malformation (SHFM) in Manitoba, Canada

We conducted a clinical population study to examine the incidence and epidemiology of split hand foot-malformation (SHFM) in Manitoba from 1957 to 2003. The total number of births during this period was 850,742. Forty-three patients with SHFM were identified, resulting in an incidence of 1 in 19,784 births. Most patients were ascertained through referrals to the Section of Genetics and Metabolism at the Children's Hospital, Winnipeg, Manitoba. Overall, 22 (51.2%) of affected individuals were females and 21 (48.8%) were male. The left upper limb (LUL) was the most frequently affected, (in 46.5% of patients). The right hand was involved in 39.5%. In 4 patients (9.3%) all four limbs were affected. SHFM is classified as a failure of formation of parts according to the International Federation of Surgical Societies of the Hand (IFSSH) and has also been categorized as Typical or Atypical. Individuals in the Manitoba cohort were classified into two main categories: Typical (29 cases) and Atypical (3 cases). However, 11 patients were not easily placed into either group and comprised a distinct category termed "difficult to classify." Patients in the three groups were then further subdivided depending on whether or not they had additional congenital anomalies. These complex patients included those with single gene disorders in which SHFM has been reported (e.g., ectodermal dysplasia Ectrodactyly Clefting (EEC), tibial aplasia with SHFM, fibular aplasia with SHFM), as well as those with other recognized or unknown patterns of anomalies. Two had deletions involving 9q and 5p respectively. Unlike some other studies, we did not find an excess of males or right-sided defects and only two of the cases--two sisters--were related.

ECLAMC: the Latin-American collaborative study of congenital malformations

DEFINITION

ECLAMC ('Estudio Colaborativo Latino Americano de Malformaciones Congenitas') is a program for the clinical and epidemiological investigation of risk factors in the etiology of congenital anomalies in Latin-American hospitals, using a case-control methodological approach. It is a voluntary agreement among professionals lacking institutional base as well as designated budgets. ECLAMC has been usually funded by research-funding agencies rather than public health ministries. The National Research Councils of Argentina and Brazil have been the main sources of support during its 36 years of existence. Since vital and health statistics are unreliable in South America, ECLAMC collects all the information required for the denominators in a hospital-based sample of births. ECLAMC can be defined as a continental network of persons interested in research and prevention of birth defects.

HISTORY AND EVOLUTION

From the institutional point of view, ECLAMC has had headquarters in diverse centers of Argentina and Brazil, but always as an independent research project, without a defined administrative link. ECLAMC began operating in 1967, as an investigation limited to the city of Buenos Aires, Argentina, and it gradually expanded until covering all the 10 countries of South America as well as Costa Rica and the Dominican Republic. Even though ECLAMC has maintained essentially the same original experimental design since 1967, due to the data accumulated by the program, the increasing experience as well as the development in science, technical modifications occurred including a DNA bank and a fully informatized data handling system. Since 1974 ECLAMC has been a founder member of the International Clearinghouse for Birth Defects Monitoring Systems; since 1994 a WHO Collaborating Center for the Prevention of Congenital Malformations, and since 2000 a collaborating member of the NIH Global Netwok for Women's and Children's Health Research.

METHODOLOGY

The maternity hospital network of ECLAMC examines around 200,000 births per year. All major and minor anomalies diagnosed at birth in infants weighing 500 g or more are registered according to a manual of procedures. The next non-malformed baby of the same sex born in the same hospital is selected as a control subject for each case. Thus, a one-to-one healthy control group matched by sex, time and place of birth is obtained. As a system of epidemic surveillance, ECLAMC systematically observes the fluctuations in the frequencies of different malformations and, in the case of an alarm for a probable epidemic of a given malformation, at a given moment, and given area, it acts to identify its cause. As termination of pregnancy has severe legal restrictions in South America, prevention of birth defects should concentrate on primary, preconceptional and tertiary measures. Tertiary measures aim to avoid complications of the affected patients from the medical, psychological, and social standpoints.

Chorionic villus sampling and amniocentesis

PURPOSE OF REVIEW

The advantages and disadvantages of common invasive methods for prenatal diagnosis are presented in light of new investigations.

RECENT FINDINGS

Several aspects of first-trimester chorionic villus sampling and mid-trimester amniocentesis remain controversial, especially fetal loss rate, feto-maternal complications, and the extension of both sampling methods to less traditional gestational ages (early amniocentesis, late chorionic villus sampling), all of which complicate genetic counseling. A recent randomized trial involving early amniocentesis and late chorionic villus sampling has confirmed previous studies, leading to the unquestionable conclusion that transabdominal chorionic villus sampling is safer. The old dispute over whether limb reduction defects are caused by chorionic villus sampling gains new vigor, with a paper suggesting that this technique has distinctive teratogenic effects. The large experience involving maternal and fetal complications following mid-trimester amniocentesis allows a better estimate of risk for comparison with chorionic villus sampling.

SUMMARY

Transabdominal chorionic villus sampling, which appears to be the gold standard sampling method for genetic investigations between 10 and 15 completed weeks, permits rapid diagnosis in high-risk cases detected by first-trimester screening of aneuploidies. Sampling efficiency and karyotyping reliability are as high as in mid-trimester amniocentesis with fewer complications, provided the operator has the required training, skill and experience.

Epidemiology of limb loss and congenital limb deficiency: a review of the literature

OBJECTIVE

To examine the state of research on population-based studies of the incidence of limb amputation and birth prevalence of limb deficiency.

DATA SOURCES

A total of 18 publication databases were searched, including MEDLINE, CINAHL, and the Cochrane Library.

STUDY SELECTION

The search was performed by using a hierarchical process. Articles were reviewed for inclusion by 3 reviewers. Inclusion criteria included defined catchment area, calculation of population-based incidence rates, defined etiology of limb loss, and English language. Review articles, animal studies, case reports, cohort studies, letters, and editorials were excluded.

DATA EXTRACTION

Figures on the estimated incidence of amputation and birth prevalence of congenital limb deficiency were gleaned from selected reports and assembled into a table format by etiology.

DATA SYNTHESIS

The studies varied in scope, quality, and methodology, making comparisons between studies difficult. Incidence rates of acquired amputation varied greatly between and within nations. Rates of all-cause acquired amputation ranged from 1.2 first major amputations per 10,000 women in Japan to 4.4 per 10,000 men in the Navajo Nation in the United States between 1992 and 1997. Consistent among all nations, the risk of amputation was greatest among persons with diabetes mellitus.

CONCLUSIONS

Surveillance of congenital limb deficiency exists in much of the developed world. Existing studies of acquired amputation suffer from a host of methodologic problems. Future efforts should be directed toward the application of standardized measures and methods to enable trends to be evaluated over time and comparisons to be made within and between countries.

5-Aza-2'-deoxycytidine-induced cytotoxicity and limb reduction defects in the mouse

BACKGROUND

5-Aza-2'-deoxycytidine (dAZA), causes hindlimb phocomelia in CD-1 mice. Studies in our laboratory have examined the hypothesis that compound- induced changes in gene expression may uniquely affect hindlimb pattern formation. The present study tests the hypothesis that dAZA causes limb dysplasia by inducing cytotoxicity among rapidly proliferating cells in the limb bud mesenchyme.

METHODS

Pregnant CD-1 mice were given a teratogenic dose of dAZA (i.p.) at different times on GD 10 and fetuses evaluated for skeletal development in both sets of limbs by standard methods. Using general histology and BrdU immunohistochemistry, limb mesenchymal cell death and cell proliferation were then assessed in embryos at various times post dosing, shortly after initial limb bud outgrowth. The effect of dAZA on early limb chondrogenesis was also studied using Northern analysis of scleraxis and Alcian blue staining of whole mount limb buds.

RESULTS

Compound related hindlimb defects were not restricted to a specific set of skeletal elements but consisted of a range of temporally related limb anomalies. Modest defects of the radius were observed as well. These results are consistent with a general insult to the limb mesenchyme. Mesenchymal cell death and reduced cell proliferation were also observed in both sets of limbs. The timing and location of these effects indicate a role for cytotoxicity in the etiology of dAZA induced limb defects. These effects also agree with the greater teratogenicity of dAZA in the hindlimb because they were more pronounced in that limb. The expression of scleraxis, a marker of early chondrogenesis, was reduced 12 hr after dAZA exposure, a time coincident with maximal cell death, as was the subsequent emergence of Alcian blue stained long bone anlagen.

CONCLUSIONS

These findings support the hypothesis that cytotoxic changes in the limb bud mesenchyme during early limb outgrowth can induce the proximal limb truncations characteristic of phocomelia after dAZA administration.

What invasive procedure to use in early pregnancy?

As scientific knowledge and medicine advance so do the expectations of the general public. Advances in molecular biology, ultrasonography, access to the early gestational sac and prenatal diagnosis have helped both drive and meet these expectations. We discuss the use, advantages, potential risks and complications of invasive prenatal diagnostic procedures in early pregnancy. All invasive procedures should be performed under continuous ultrasound guidance by experienced operators. Within this context, mid-trimester amniocentesis remains the safest invasive procedure. Chorionic villus sampling (CVS) and early amniocentesis (EA) are associated with a higher risk of subsequent pregnancy loss. There is also a 10-fold increase in the risk of mosaicism with CVS compared to amniocentesis. Both CVS and EA can induce fetal structural defects and should be abandoned as routine invasive tests. Patient counselling should include an evaluation of the risk associated with each individual procedure but also the operator's personal complication rate.

Pregnancy outcome after exposure to misoprostol in Brazil: a prospective, controlled study

BACKGROUND

Misoprostol, a synthetic prostaglandin E1 analog is labeled for the treatment of gastric and duodenal ulcers. In Brazil, where abortion is not a legal procedure, there is a widespread popular misuse of this drug in abortion attempts. This misuse and the fact that, in many cases the desired pregnancy termination does not occur, raise concerns about fetal safety. Case reports of congenital anomalies after maternal use of misoprostol have been published. The objective of this work was to compare pregnancy outcome following misoprostol exposure with a matched control group. This is the first prospective controlled study on fetal safety after misoprostol use.

METHODS

A prospective, observational cohort study with 86 exposed and 86 pair-matched, non-exposed controls.

RESULTS

There was no significant difference in the rates of major or minor birth between exposed compared to non-exposed infants (2/67 vs 2/81, major defects; 7/67 vs. 3/81, minor anomalies) There were significantly more miscarriages in the exposed group (17.1% vs. 5.8%; relative risk, 2.97; 95% confidence interval, 1.12 to 7.88). There was no statistical difference in gestational age at delivery, birth weight, sex ratio, rate of prematurity, low birth weight, or rates of cesarean section between groups.

CONCLUSIONS

Our study, despite its limited statistical power, does not suggest a potent teratogenic action of misoprostol exposure during pregnancy.

The return of thalidomide: are birth defects surveillance systems ready?

In the 1960s, thalidomide caused limb deficiencies in thousands of infants worldwide. The limb deficiencies were frequently of the intercalary type. As a result, numerous countries started birth defect surveillance programs. In 1967, the Centers for Disease Control (CDC) started the Metropolitan Atlanta Congenital Defects Program (MACDP), a population-based surveillance system, to provide early warning against new teratogens. Recent studies have shown that thalidomide may be beneficial for a range of conditions, including cancer and AIDS, and it may once again become widely available. Here, we examine the ability of MACDP to detect an increase in the birth prevalence of limb deficiency as an early warning of fetal exposure to thalidomide. We calculated base rates for all limb deficiencies, for bilateral nonsyndromic intercalary or preaxial deficiencies, and for all nonsyndromic intercalary limb deficiencies among Atlanta infants born from 1968 through 1993. We used relative risk estimates from previous studies and a range of pregnancy exposure rates for thalidomide. We tested the statistical power of MACDP to detect subtle changes in the birth prevalence of these defects using Poisson and cumulative sum (CUSUM) techniques. The base rates for all limb deficiencies, for bilateral intercalary or preaxial deficiencies, and for all intercalary limb deficiencies, were 0.53, 0.035, and 0.022/1,000, and the estimated relative risks were 175, 4,570, and 8,180, respectively. We varied the assumed rate of exposure to thalidomide from 1/10,000 to 5/100. With a 1/1,000 exposure rate, both Poisson and CUSUM techniques will detect a rate change in intercalary limb deficiency in about 6 months of monitoring, and a rate change in bilateral intercalary or preaxial deficiencies in about 12 months of monitoring. When monitoring all limb deficiencies, a pregnancy exposure rate of 3.5% or less would go unnoticed by the Poisson method and would take more than 50 years for the CUSUM method to signal an alarm with a 1/1,000 exposure rate. However, for rates of exposure less than 1/1,000, a progressively longer period of time or larger sample are needed to detect a rate change by both methods. Our findings highlight the importance of enlarging the monitored population and correct case classification in birth defects surveillance.

The epidemiology of preaxial limb malformations

The epidemiology of preaxial limb malformations was studied in an effort to find similarities and differences between different types that could help to define suitable groups of malformations for etiologic studies. Material from three large congenital malformation registers was used, with a total of 1646 infants with such malformations among over 5 million births. We compared different types of preaxial malformations with respect to bilaterality, maternal age and parity, racial differences, sex distribution, twinning, and associated malformations. From many epidemiologic aspects, different types of preaxial malformations showed similarities, but there were some distinct differences between upper and lower limb anomalies. We conclude that in searches for etiologic factors, it may be useful to group all preaxial malformations together but to differentiate between upper and lower limb defects.

Thalidomide, a current teratogen in South America

Thalidomide, mainly used for the treatment of leprosy, is a current teratogen in South America, and it is reasonable to assume that at present this situation is affecting many births in underdeveloped countries. Moreover, the potential re-marketing of thalidomide for the treatment of a large variety of diseases may extend the problem to the developed world. When the drug is available, the control of its intake during early pregnancy is very difficult since most pregnancies are unintended. The ongoing occurrence of thalidomide embryopathy cases went undetected by the ECLAMC, due to several factors: (1) low populational coverage through this monitoring system; (2) pre-existence of the teratogen with its effects present in both baseline (expected) and monitored (observed) materials; and (3) lack of a defined phenotype to be monitored. Thus, if thalidomide re-enters the market throughout the world, due to the wide range of new applications, occurrence of phocomelia alone might not be sufficient to detect its effects. By a case-reference approach, the ECLAMC registered 34 thalidomide embryopathy cases born in South America after 1965 whose birthplaces correspond to endemic areas for leprosy. Phocomelia was found in five of eleven fully described cases. Thus, phocomelia alone is neither specific nor sufficient to serve as a suitable phenotype to survey the teratogenic effects of thalidomide. Therefore, a thalidomide-like phenotype, defined as any bilateral upper and/or lower limb reduction defect of the preaxial and/or phocomelia types, should be included in the routine surveillance of birth defects in all programmes.