Rats deficient C-type natriuretic peptide suffer from impaired skeletal growth without early death.

We have previously investigated the physiological role of C-type natriuretic peptide (CNP) on endochondral bone growth, mainly with mutant mouse models deficient in CNP, and reported that CNP is indispensable for physiological endochondral bone growth in mice. However, the survival rate of CNP knockout (KO) mice fell to as low as about 70% until 10 weeks after birth, and we could not sufficiently analyze the phenotype at the adult stage. Herein, we generated CNP KO rats by using zinc-finger nuclease-mediated genome editing technology. We established two lines of mutant rats completely deficient in CNP (CNP KO rats) that exhibited a phenotype identical to that observed in mice deficient in CNP, namely, a short stature with severely impaired endochondral bone growth. Histological analysis revealed that the width of the growth plate, especially that of the hypertrophic chondrocyte layer, was markedly lower and the proliferation of growth plate chondrocytes tended to be reduced in CNP KO rats. Notably, CNP KO rats did not have malocclusions and survived for over one year after birth. At 33 weeks of age, CNP KO rats persisted significantly shorter than wild-type rats, with closed growth plates of the femur in all samples, which were not observed in wild-type rats. Histologically, CNP deficiency affected only bones among all body tissues studied. Thus, CNP KO rats survive over one year, and exhibit a deficit in endochondral bone growth and growth retardation throughout life.

Midterm Survivorship and Complications of Total Knee Arthroplasty in Patients With Dwarfism.

BACKGROUND: Dwarfism is associated with skeletal dysplasias and joint deformities that frequently result in osteoarthritis requiring treatment with total knee arthroplasty (TKA). These surgeries can be challenging because of alignment deformities, poor bone stock, and smaller components. This study aims to compare TKA implant survivorship and complications between dwarf and nondwarf patients. METHODS: A retrospective case-control study was performed from 1997-2014 evaluating 115 TKAs in patients under the height threshold of 147.32 cm. This cohort was compared with 164 patients of normal height. Medical records were reviewed for demographics, surgical characteristics, and outcomes. All cases had 2-year minimum follow-up. RESULTS: The revision rate was 8.7% in dwarfs compared with 3.7% in controls (P = .08). The 2-, 5-, and 10-year implant survivorship in dwarfs was 96.4%, 92.5%, and 90.2%, respectively; and 96.6%, 95.6%, and 94.8% for controls, respectively (P = .24). Dwarfs underwent significantly more manipulations for arthrofibrosis (P = .002). There was greater femoral (17.4% vs 2.1%, P < .01) and tibial (6.5% vs 2.7%, P < .01) component overhang in dwarfs compared with controls. CONCLUSION: Despite a 2-fold increase in the revision rate of the dwarf cohort, the midterm survivorship is comparable between the dwarf and nondwarf patients. However, dwarfs were more likely to become stiff and undergo manipulation; the increased propensity for stiffness may be associated with oversized components, as evidenced by greater component overhang. Surgeons should be aware of this increased risk and may consider using smaller or customized implants to account for the morphological differences in this patient population.

Non lethal Raine syndrome and differential diagnosis.

Raine syndrome is a rare autosomal recessive bone dysplasia characterized by characteristic facial features with exophthalmos and generalized osteosclerosis. Amelogenesis imperfecta, hearing loss, seizures, and intracerebral calcification are apparent in some affected individuals. Originally, Raine syndrome was originally reported as a lethal syndrome. However, recently a milder phenotype, compatible with life, has been described. Biallelic variants inFAM20C, encoding aGolgi casein kinase involved in biomineralisation, have been identified in affected individuals. We report here a consanguineous Moroccan family with two affected siblingsa girl aged 18 and a boy of 15years. Clinical features, including learning disability, seizures and amelogenesis imperfecta, initially suggested a diagnosis of Kohlschutter-Tonz syndrome. However,a novel homozygous FAM20Cvariantc.676T > A, p.(Trp226Arg) was identified in the affected siblings. Our report reinforces that Raine syndrome is compatible with life, and that mild hypophosphatemia and amelogenesis imperfecta are key features of the attenuated form.

Approach to the diagnosis of skeletal dysplasias: Experience at a center with limited resources.

PURPOSE: A fetus with skeletal disorder poses diagnostic challenges in a resource-poor setting with limited management options. The objective of the study was to develop a step-by-step approach for the diagnosis of skeletal dysplasia in light of the limited resources available. METHODS: An algorithmic approach was used. The assessment for lethality was the first step, followed by the evaluation for fractures. In cases without evidence of fracture, severe constriction of thorax or associated polydactyly were searched for. In cases without severe thoracic constriction, the severity of micromelia was evaluated. After delivery, fetal examination was done to ascertain the etiology. RESULTS: During the 6-year period, 41 cases with shortened long bones were fully evaluated. Lethality was suspected in 30 cases. Fracture and beading were present in eight cases, and severe thoracic constriction with polydactyly was observed in seven cases. Mild micromelia was seen in 19 cases and severe micromelia in 7 cases. Among lethal skeletal dysplasias, thanatophoric dysplasia was most common (six cases). Among nonlethal skeletal dysplasias, achondroplasia was seen in eight cases. CONCLUSIONS: Lethality of skeletal dysplasia could be predicted on prenatal ultrasound with 100% accuracy. The step-by-step approach was helpful to characterize skeletal dysplasias. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:529-539, 2016.

Adolescents and Young Adults with Chronic or End-Stage Kidney Disease.

BACKGROUND: Adolescents and young adults face unique and complex physical, psychological, and family challenges. Despite improvements in care for chronic kidney disease (CKD) and end-stage kidney disease (ESKD), long-term mortality for children, adolescents, and young adults with CKD remains substantially higher than their healthy counterparts. SUMMARY: In this article, we discuss the complex challenges that adolescent and young adult CKD/ESKD patients face. Adolescents have different CKD etiologies and progress along a course dissimilar to the adult population, but have similar multifarious comorbidities. In the setting of puberty and learning to become self-sufficient, adolescence is a critical time for growth and psychosocial development. Physiological complications of CKD underlie many of the long-term outcomes. CKD-mineral and bone disorder and anemia are particularly challenging given that they are exacerbated by the rapid growth of adolescents. Endocrine imbalances and malnutrition can delay and limit growth. All of these factors, together with family dynamics and socioeconomic status, contribute to the poor long-term outcomes and decreased quality of life (QoL) for these patients and their families. KEY MESSAGES: Care for the adolescent CKD/ESKD population is uniquely challenging, but research has identified ways in which we can continue to improve long-term outcomes and QoL for adolescents with CKD/ESKD.

Fetal skeletal dysplasias: sonographic indices associated with adverse outcomes.

OBJECTIVES: To assess the utility of biometric indices and amniotic fluid volume in identifying fetuses with lethal skeletal dysplasia. METHODS: A review of pregnancies with sonographic diagnosis of skeletal dysplasia between January 1997 and March 2012 from a single institution was conducted. Biometric indices and amniotic fluid volumes were reviewed from the initial targeted sonograms and all subsequent examinations. Outcomes were verified in all cases. Pregnancies that resulted in fetal or neonatal death were considered to have lethal dysplasia, and those with survival to hospital discharge were considered to have nonlethal dysplasia. RESULTS: Of 45 fetuses with suspected skeletal dysplasia, 27 (60%) survived to hospital discharge; 9 (20%) died in the immediate neonatal period; 2 (4%) resulted in stillbirth; and in 7 cases (16%), pregnancy termination was elected. Those with lethal dysplasia were more likely to have hydramnios on initial detection than those who survived to hospital discharge (83% versus 27%; P < .01). Pregnancies complicated by lethal skeletal dysplasia had a significantly lower femur length-to-abdominal circumference ratio and were more likely to have a ratio below 0.16 than those with neonatal survival (91% versus 11%; P < 0.01). The lowest femur length-to-abdominal circumference ratio and the proportion with a ratio below 0.16 at any point in gestation were significantly different between those with lethal and nonlethal dysplasia (P< .01). As fetal size increased with advancing gestation, the relationship of sonographic parameters (eg, femur length-to-abdominal circumference ratio) became more pronounced. There was no infant survival when hydramnios was encountered at any point during gestation in the setting of a femur length-to-abdominal circumference ratio below 0.16. CONCLUSIONS: In our series, a femur length-to-abdominal circumference ratio below 0.16 in conjunction with hydramnios effectively identified fetuses with lethal skeletal dysplasia.

FAM111A mutations result in hypoparathyroidism and impaired skeletal development.

Kenny-Caffey syndrome (KCS) and the similar but more severe osteocraniostenosis (OCS) are genetic conditions characterized by impaired skeletal development with small and dense bones, short stature, and primary hypoparathyroidism with hypocalcemia. We studied five individuals with KCS and five with OCS and found that all of them had heterozygous mutations in FAM111A. One mutation was identified in four unrelated individuals with KCS, and another one was identified in two unrelated individuals with OCS; all occurred de novo. Thus, OCS and KCS are allelic disorders of different severity. FAM111A codes for a 611 amino acid protein with homology to trypsin-like peptidases. Although FAM111A has been found to bind to the large T-antigen of SV40 and restrict viral replication, its native function is unknown. Molecular modeling of FAM111A shows that residues affected by KCS and OCS mutations do not map close to the active site but are clustered on a segment of the protein and are at, or close to, its outer surface, suggesting that the pathogenesis involves the interaction with as yet unidentified partner proteins rather than impaired catalysis. FAM111A appears to be crucial to a pathway that governs parathyroid hormone production, calcium homeostasis, and skeletal development and growth.

Analysis of skeletal dysplasias in the Utah population.

The Utah Birth Defect Network (UBDN) collects population-based data for Utah on births from all resident women. The prevalence of skeletal dysplasias and epidemiologic characteristics/outcomes were evaluated. Cases categorized as a skeletal dysplasia from all live births, stillbirths, and pregnancy terminations (TAB) between 1999 and 2008 were reviewed by three clinical geneticists. After case review, 153 were included for analysis (88% live births, 3% stillborn, 9% TAB), and categorized by groupings defined by molecular, biochemical, and/or radiographic criteria as outlined in the 2010 Nosology and Classification of Genetic Skeletal Disorders. The overall prevalence for skeletal dysplasias was 3.0 per 10,000 births, and 20.0 per 10,000 stillbirths. The most common diagnostic groups were osteogenesis imperfecta (OI; n = 40; 0.79 per 10,000), thanatophoric dysplasia (n = 22; 0.43 per 10,000), achondroplasia (n = 18; 0.35 per 10,000), and cleidocranial dysplasia (n = 6; 0.12 per 10,000). The most common groups based on the 2010 Nosology and Classification of Genetic Skeletal Disorders were the FGFR3 chondrodysplasia group (n = 41; 0.81 per 10,000), the OI/decreased bone density group (n = 40; 0.79 per 10,000), and the type 2 collagen group (n = 10; 0.2 per 10,000). Median age of postnatal diagnosis was 30 days (range 1-2,162). Of those deceased, 88% were prenatally suspected; of those alive 29% prenatally suspected. Median age of death for live born individuals was 1 day (range 1-1,450 days). Previously reported prevalence rates vary, but our data provide a population-based approach not limited to the perinatal/neonatal period. Understanding the range for survival within each group/diagnosis is beneficial for health care providers when counseling families.

Accuracy of prenatal diagnosis and prediction of lethality for fetal skeletal dysplasias.

OBJECTIVES: We reviewed all cases with fetal skeletal dysplasia and correlated the accuracy of prenatal diagnoses with the final post-mortem, radiological, or molecular diagnoses. The accuracy of prenatal prediction of lethality was also reviewed. METHODS: All cases of fetal skeletal dysplasia referred between October 2002 and August 2010 were reviewed. Perinatal outcome, the accuracy of prenatal diagnosis, and prediction of lethality were ascertained. Lethality was suspected when significant thoracic narrowing, severe micromelia, multiple fractures, or long bone bowing was present. RESULTS: There were 40 cases of skeletal dysplasia. Thirty-nine (97.5%) were singletons and one (2.5%) was a dichorionic twin pregnancy. Twenty-eight (70%) pregnancies were terminated, five (12.5%) were stillborn, and only seven (17.5%) cases were live born. A final diagnosis was established in 28 (70%) cases. In 29 cases with a presumptive prenatal diagnosis, this was confirmed in 23 (79.3%) cases postnatally. Lethality was predicted with 100% certainty. CONCLUSION: We report higher prenatal/postnatal concordance rates in this series. A precise prenatal diagnosis is frequently difficult and often inaccurate. Prediction of lethality is much easier and often possible with accuracy. Parents need to be aware that the outcome of many skeletal dysplasias is poor.

Displasia campomélica: reporte de un caso / Campomelic dysplasia: case report

La displasia campomélica es una osteocondrodisplasia rara y severa caracterizada por alteraciones esqueléticas y no esqueléticas con una alta letalidad en el período neonatal. Este síndrome se caracteriza por acortamiento y angulación de las extremidades inferiores, principalmente el fémur. En cuanto a su mecanismo de transmisión, la mayoría de los casos es de tipo autosómico recesivo; sin embargo, puede ocurrir esporádicamente de forma autosómica dominante, por mutación del gen Sox9 localizado en el cromosoma 17. Presentamos un caso de un neonato masculino, sin antecedentes de consanguinidad entre los padres, con signos característicos de displasia campomélica tales como talla baja 40 cm, macrocefalia (circunferencia cefálica 34 cm), dolicocefalia, tronco y extremidades inferiores cortas. También se encontraron otras alteraciones tales como tórax estrecho en forma de campana, angulación de fémur, hipertelorismo, puente nasal deprimido, micrognatia e implantación baja de las orejas. El neonato falleció a los 2 días de vida producto de insuficiencia respiratoria la cual presentó desde el nacimiento.

The natural histories of bone dysplasias in adults--vignettes, fables and just-so stories.

The bone dysplasias are a heterogeneous group of disorders arising from intrinsic abnormality of bone and cartilage growth and function. All are genetic. Most result in extreme small stature (dwarfism). Historically, emphasis was primarily on diagnostic identification of specific disorders in infants (including differentiating lethal and non-lethal forms), and on the clinical history to be anticipated in infants and children with each of these specific processes. Even in children there is exceedingly limited information of quality and virtually no controlled studies of the effects of intervention. For the most part, information about affected adults is even less complete and even less rigorous. Presented here are a series of examples of medical and adaptive issues in adults affected by one or another of the genetic skeletal dysplasias. Topics discussed include: approach to adults with no specific diagnosis; medical issues that cross diagnostic boundaries (osteoarthritis in the "E" disorders, obstructive apnea, issues in pregnancy in women with dwarfing disorders, activities of daily living, and quality of life assessments); diagnosis-specific problems of adulthood (spinal stenosis in achondroplasia, hearing loss in osteogenesis imperfecta, and malignancy risk in multiple exostoses); adult problems that must be addressed in childhood in order to be prevented (achondroplasia and kyphosis, and cervical spine abnormalities in Morquio syndrome); survival conundrums (why some live unexpectedly and others die unexpectedly). Emphasis is placed on the difficulties intrinsic to trying to learn about needs and expectations in generally rare genetic processes.

Ultrasonographic prediction of fetal outcome in suspected skeletal dysplasias with use of the femur length-to-abdominal circumference ratio.

OBJECTIVE: Our purpose was to determine whether the femur length-to-abdominal circumference ratio can be used antenatally to predict a lethal skeletal dysplasia. STUDY DESIGN: All obstetric sonograms performed from January 1990 to October 1995 were reviewed (44,020 studies) to find those scans suggestive of a skeletal dysplasia. Thirty patients were identified. The femur length/abdominal circumference ratio was then calculated from each patient's initial and subsequent sonograms. Birth outcomes were obtained on the 27 patients who elected to continue their pregnancies. RESULTS: All fetuses with a lethal skeletal dysplasia (n = 12) had a ratio <0.16. The fetuses with a nonlethal dysplasia (n = 8) had ratios between 0.134 and 0.193, with only 1 fetus with a ratio <0.16. All fetuses with no evidence of a skeletal dysplasia after birth (n = 7) had femur length/abdominal circumference ratios >0.18. The 1 fetus with a ratio <0.16 who survived the neonatal period had extreme bowing and demonstrates the limitation of the ratio when bowing is present. CONCLUSIONS: A stillbirth or neonatal death occurred in 12 of 13 patients with a femur length/abdominal circumference ratio <0.16, independent of gestational age. Conversely, no fetus with a ratio >0.16 was found to have a lethal skeletal dysplasia. This information may be useful in counseling women when ultrasonography suggests the diagnosis of a skeletal dysplasia.

The value of radiography in perinatal deaths.

A prospective study of 100 consecutive stillbirths/perinatal deaths was performed by routine radiography and subsequent autopsy. The object of the study was to correlate the clinical and the autopsy causes of death with any abnormal radiographic findings. A prime objective was to study the incidence of major skeletal abnormalities in the series and to ascertain if routine radiography could be used to detect abnormalities that might require genetic counselling. No skeletal abnormalities or dysplasias were detected that did not have obvious external stigmata. The use of routine radiography on undeformed stillbirths is not recommended.

[Lethal achondrogenesis: a review of 56 cases (author's transl)]. / Letale Achondrogenesis: Eine Ubersicht über 56 Fälle.

54 cases with lethal achondrogenesis from the literature as well as two own cases are reviewed and analyzed with regard to the following characteristics: sex, hydramnios, breech presentation, duration of pregnancy, length and weight at birth, head circumference, length of upper and lower extremities, clinical and radiological data, age of mother and father at time of birth, familial occurrence and consanguinity of parents, histological, histochemical and electronmicroscopic tissue examination.

[Atypical achondrogenesis. Review of the literature apropos of 2 cases]. / Formes frustes de l'achondrogénése. Revue de a littérature á propos de deux cas

The authors describe two cases of a minor form of achondrogenesis. This form has not been published previously. A discussion of the different possibilities of differential diagnosis follows.

Studies of the energy and protein requirements of the growing guinea-fowl.

1. Guinea-fowl of both sexes and female chickens were fed from 1 to 12 weeks on diets the energy concentration of which was constant at either 2-6, 2-9 or 3-2 Mcal/kg (10-8, 12-1 or 13-4 MJ/kg) while the calorie to protein ratios were changed, for some groups, from 124 to 157 or 200 at 4 and 8 weeks. 2. Guinea-fowl, but not chickens, were unable to overconsume when the protein concentration was low with the result that the body fat content was not reduced when the protein concentration was increased. 3. In the second trial the ME level of the diets was fixed at 12-6 MJ/kg while the protein content was varied, from 21 to 28% in the diets fed to 6 weeks of age and from 15 to 24% in those fed from 6 to 12 weeks. 4. It is concluded that for the growing guinea-fowl the diet should contain 12-6 MJ ME/kg, the protein concentration reducing from 24 to 26% in the period 0 to 4 weeks to 19 to 20% in the period 4 to 8 weeks and to 16% or less in the period 8 to 12 weeks.