Current knowledge of medical complications in adults with achondroplasia: A scoping review.

This article provides an overview of the current knowledge on medical complications, health characteristics, and psychosocial issues in adults with achondroplasia. We have used a scoping review methodology particularly recommended for mapping and summarizing existing research evidence, and to identify knowledge gaps. The review process was conducted in accordance with the PRISMA-ScR guidelines (Preferred Reporting Items for Systematic reviews and Meta-Analyses Extension for Scoping Reviews). The selection of studies was based on criteria predefined in a review protocol. Twenty-nine publications were included; 2 reviews, and 27 primary studies. Key information such as reference details, study characteristics, topics of interest, main findings and the study author's conclusion are presented in text and tables. Over the past decades, there has only been a slight increase in publications on adults with achondroplasia. The reported morbidity rates and prevalence of medical complications are often based on a few studies where the methodology and representativeness can be questioned. Studies on sleep-related disorders and pregnancy-related complications were lacking. Multicenter natural history studies have recently been initiated. Future studies should report in accordance to methodological reference standards, to strengthen the reliability and generalizability of the findings, and to increase the relevance for implementing in clinical practice.

Multicenter study of mortality in achondroplasia.

Sudden death and higher mortality are recognized in achondroplasia, with acute brainstem compression, a common cause of mortality in children <4 years and cardiovascular deaths being more prevalent in adults. Although, changes in clinical management have improved survival, mortality is still higher than in the general population. The aim of this multicenter clinic-based study was to assess the rate and causes of mortality in patients seen in clinic since 1986. Information was ascertained for achondroplasia patients clinically assessed in four skeletal dysplasia clinics. Data was sent to the National Death Index to identify vital status and cause of death. Standardized mortality rates (SMR) were calculated based on U.S. populations from 1975, 1995, and 2000. Eight hundred fifty-five patients were identified, contributing 12,117 person-years and a total of 12 deaths. One case died in infancy. In the 1-4 year age group, which had the highest age-adjusted SMR, three out of five deaths were because of cerebrovascular/cardiovascular events. Half the deaths in ages 5 through 24 were because of accidental events, including motor vehicle accidents. Decreased mortality in children with achondroplasia was noted, particularly in younger age groups. This improvement in childhood survival is outpaced by improved survival in the general population. Causes of death in these patients have shifted over the last 30 years, with fewer sudden death and deaths because of pneumonia or hydrocephalus countered by more cardiovascular or cerebrovascular and accidental deaths. Clinicians should be aware of the apparent increased risk of vehicular accidents and counsel patients accordingly.

Skeletal Characterization of the Fgfr3 Mouse Model of Achondroplasia Using Micro-CT and MRI Volumetric Imaging.

Achondroplasia, the most common form of dwarfism, affects more than a quarter million people worldwide and remains an unmet medical need. Achondroplasia is caused by mutations in the fibroblast growth factor receptor 3 (FGFR3) gene which results in over-activation of the receptor, interfering with normal skeletal development leading to disproportional short stature. Multiple mouse models have been generated to study achondroplasia. The characterization of these preclinical models has been primarily done with 2D measurements. In this study, we explored the transgenic model expressing mouse Fgfr3 containing the achondroplasia mutation G380R under the Col2 promoter (Ach). Survival and growth rate of the Ach mice were reduced compared to wild-type (WT) littermates. Axial skeletal defects and abnormalities of the sternebrae and vertebrae were observed in the Ach mice. Further evaluation of the Ach mouse model was performed by developing 3D parameters from micro-computed tomography (micro-CT) and magnetic resonance imaging (MRI). The 3-week-old mice showed greater differences between the Ach and WT groups compared to the 6-week-old mice for all parameters. Deeper understanding of skeletal abnormalities of this model will help guide future studies for evaluating novel and effective therapeutic approaches for the treatment of achondroplasia.

Mortality in babies with achondroplasia: revisited.

BACKGROUND: Natural history studies performed 30 years ago identifying higher mortality among children born with achondroplasia, a genetic dwarfing condition, resulted in clinical recommendations aimed at improving mortality in childhood. The objective of this study was to determine if mortality rates have changed over the past few decades. METHODS: Children born with achondroplasia during 1996 to 2003 were ascertained from the Texas Birth Defects Registry and matched with death certificate data from the Bureau of Vital Statistics through 2007. Infant and overall mortality rates, both crude and standardized to the 2005 (SMR2005 ) and 1975 (SMR1975 ) U.S. populations, were calculated. RESULTS: 106 children born with achondroplasia were identified. Four deaths were reported, with all occurring in the first year of life (mortality rate: 41.4 /1000 live-births). Infant mortality was higher when standardized to the 2005 U.S. population (SMR2005 :6.02, 95% CI:1.64-15.42) than the 1975 population (SMR1975 :2.58, 95% CI:0.70-6.61). CONCLUSION: The higher SMR2005 compared with SMR1975 , along with the fact that SMR1975 was nearly half that of a previous cohort reported 25 years ago (rate ratio: 0.53, 95% CI: 0.11-2.25), reflect a discrepancy in the changes in mortality in the overall population and in our cohort. Although an overall improvement in mortality, especially after the first year of life, is observed in our cohort, children with achondroplasia are still at a much higher risk of death compared with the general population. A longer follow-up is needed to elucidate whether evaluation/intervention changes have resulted in significant improvement in long-term survival among these patients.

Mortality in achondroplasia study: a 42-year follow-up.

Achondroplasia (ACH) is the most common dwarfing condition having a prevalence of 1/25,000 live births. An increase in overall mortality, age specific mortality up to age 34 years and heart disease-related mortality was first reported in a 1987 study of a large population of ACH individuals. Since this study, concern about premature death, particularly in young adults, has persisted in the ACH population. The present study was undertaken to follow-up the patterns of mortality in a more contemporaneous ACH population. The vital status of 718 ACH individuals from the original study and 75 new ACH individuals was determined through the search of two computerized mortality database. The results showed that the overall mortality and age-specific mortality at all ages remained significantly increased. Rates of death were similar across all 42 years of follow-up suggesting that higher death rates were still occurring in the contemporary ACH population. Accidental, neurological, and heart disease-related deaths were increased in adults. Heart disease-related mortality, between ages 25 and 35, was more than 10 times higher than the general population. Overall survival and the average life expectancy for this ACH population were decreased by 10 years. These results demonstrate that despite advances in the knowledge of the natural history of ACH and health care needs of this population, mortality remains significantly increased. The high rate of heart disease related deaths illustrates the need to identify risk factors in the ACH population and develop treatment interventions accordingly.

Living with achondroplasia: quality of life evaluation following cervico-medullary decompression.

Achondroplasia is the most common of the heritable skeletal dysplasias. Cervico-medullary compression is a frequently encountered and potentially lethal neurological complication. Cervico-medullary decompression (CMD) at the foramen magnum is often employed to relieve the pressure on the emerging cervical cord. Given the inherent risks associated with major surgery, there has been a substantial debate regarding the best criteria for CMD. Our objectives for this study are to explore the quality of life of patients who had undergone CMD, and to assess whether surgery is associated with mortality and increased long-term morbidity. A Medical Outcome Study 36-item Short Form General Health Survey designed to evaluate eight general health concepts as well as achondroplasia-related issues, was administered to patients assessed in the neurosurgery department in Johns Hopkins Hospital between 1977 and 1998. One hundred and sixty-seven patients were eligible for inclusion. Forty-three could not be contacted, and two refused consent. One hundred and twenty-two patients were assessed. Fifty-six (46%) individuals had CMD and 66 (54%) did not. There was 1 case of mortality in the CMD group and 12 cases in the non-CMD group. In the non-CMD group, all deaths, as far as we know, were unrelated to cervico-medullary compression. In this cohort of surviving patients (n = 109), the quality of life of the 55 (50.5%) who had undergone CMD is comparable to that of the 54 (49.5%) who did not have surgery, controlled for age and sex. CMD is indicated for patients with achondroplasia with significant symptomatic foramen magnum compression. It can be life saving. It can abolish profound central apnea that may cause sudden death and alleviate neurological complications associated with damage of the significantly compressed spinal cord. With regards to long-term outcome evaluation, the quality of life of individuals with achondroplasia who had CMD is similar to those age- and sex-matched patients who did not have this surgery. Moreover, CMD, with all its inherent surgical risks, does not appear to be associated with higher mortality or increased long-term morbidity.

Achondroplasia and cervicomedullary compression: prospective evaluation and surgical treatment.

The association between sudden death and cervicomedullary compression in infants with achondroplasia has been well described. Prospective clinical and imaging evaluations have been recommended to identify those infants with achondroplasia who are at risk of dying suddenly from respiratory arrest secondary to unrecognized cervicomedullary compression. Since 1988, we have prospectively evaluated 11 infants (average age 13 weeks) with achondroplasia who were asymptomatic for cervicomedullary compression on initial clinical evaluation. Craniocervical magnetic resonance imaging (MRI) findings included narrowing of the foramen magnum, effacement of the subarachnoid spaces at the cervicomedullary junction, abnormal intrinsic cord signal intensity and mild to moderate ventriculomegaly. Two patients with severe cord compression underwent immediate decompression. Two patients developed opisthotonic posturing within 3 months of evaluation and underwent foramen magnum decompression, including suboccipital craniectomy and atlantal laminectomy. Surgery in all cases revealed forward extension of the squamous portion of the occipital bone, thickened posterior rim of the foramen magnum and a dense fibrotic epidural band. There were no complications from surgery. Seven patients did not require surgery and were followed closely. All 11 patients remain asymptomatic at follow-up (mean 4.6 years; range 16 months to 7.3 years), and no patient has required a diversionary shunt procedure. The results of this prospective study confirm that early clinical and MRI evaluations are necessary to determine whether infants with achondroplasia have cervicomedullary compression. With early recognition, an immediate decompression can be performed safely to avoid serious complications associated with cervicomedullary compression, including sudden death.

[Fatal nanism: 3 different entities]. / Enanismos letales: tres entidades diferentes.

Three cases of congenital dwarfism are presented. All of them are lethal and represent the three better known nonviable nosologic entities: Achondrogenesis I, Achondrogesis II and Thanatophoric dwarfism. According to clinical features and radiologic data it is possible to approach the diagnosis accurately. We comment genetic, clinic, radiologic and histologic aspects of these processes. It is important to establish a differential diagnosis as these entities have different genetic basis, what influences genetic counsel.

Mortality in achondroplasia.

Standardized mortality ratios (SMRs) were determined for a historical cohort of achondroplastic individuals identified through the Medical Genetics Clinics of the University of Texas Health Science Center at Houston and Johns Hopkins Hospital, Baltimore. Mortality was increased at all ages, with an overall SMR of 2.27 (95% confidence interval 1.7-3.0). Sudden death accounted for the excess deaths in those less than 4 years of age, and brain-stem compression was identified as the cause in half of these deaths. Central nervous system and respiratory causes were not significantly increased but accounted for half of the deaths in those 5-24 years of age. SMRs were not significantly increased for those greater than 34 years of age. However, deaths attributed to cardiovascular causes were increased in the 25-54-year-old age group, accounting for 10 of 17 deaths. The overall cardiovascular SMR was 5.2 (95% confidence interval 2.5-9.6). Within this group, severe disability resulting from marked spinal canal stenosis was present in a majority of individuals and may have been a contributing factor in these deaths. This study suggests that the bony abnormalities associated with achondroplasia--i.e., foramen magnum and spinal canal stenosis--may have a significant effect on mortality at all ages but particularly in children. Efforts to minimize these complications are recommended.

Homozygous achondroplasia with survival beyond infancy.

Homozygous achondroplasia has been thought to be uniformly lethal in the neonatal period. We describe three children, born to achondroplastic parents, who were homozygous for this disorder but who survived beyond early infancy. Two died suddenly at 37 and 33 mo; the third survives at 29 wk. At least in some instances aggressive treatment may allow others with this condition to survive with a reasonable quality of life.

New forms of neonatal death dwarfism. Report of 3 cases.

The term Lethal Neonatal Dwarfism (Death Dwarfism) denotes bone dysplasias which always have a fatal outcome. Three different cases of "new" forms of death dwarfism are reported. A babygram should be a routine examination in all the cases of stillborn babies or those who die soon after the birth. If then the diagnosis cannot be established microscopic investigations of the growth cartilage should be performed.