Digynic triploid infant surviving for 46 days

We report on a triploid infant who survived for 46 days. She had severe intrauterine growth retardation, relative macrocephaly, and a small, noncystic placenta, which are manifestations compatible with type II phenotype. Cultured amniotic fluid cells, skin fibroblasts, cord blood, and peripheral blood lymphocytes all showed a nonmosaic 69,XXX karyotype. Analysis of chromosomal heteromorphisms and microsatellite DNA polymorphisms in the infant and her parents indicated that the extra haploid set in the infant resulted from nondisjunction at maternal second meiosis. Postzygotic, mitotic nondisjunction was ruled out because of the presence of both homozygous and heterozygous markers of maternal origin. A search of the literature demonstrated five triploid infants, including the girl we described, who survived 4 weeks or more, and the parental origin of whose triploidy was studied: four were digynic and one was diandric. These findings support the notion that type II triploids are digynic in parental origin and that they survive longer than type I, diandric triploids.     

Common mutations in the fibroblast growth factor receptor 3 (FGFR3) gene account for achondroplasia,hypochondroplasia, and thanatophoric dwarfism

The mapping of the achondroplasia locus to the short arm of chromosome 4 and the subsequent identification of a recurrent missense mutation (G380R) in the fibroblast growth factor receptor 3 (FGFR-3) gene has been followed by the detection of common FGFR-3 mutations in two clinically related disorders: thanatophoric dwarfism (types I and II) and hypochondroplasia. The relative clinical homogeneity of achondroplasia was substantiated by demonstration of its genetic homogeneity as more than 98% of all patients hitherto reported exhibit mutations in the transmembrane receptor domain. Although most hypochondroplasia cases were accounted for by a recurrent missense substitution (N540K) in the first tyrosine kinase (TK 1) domain of the receptor, a significant proportion (40%) of our patients did not harbor the N540K mutation and three hypochondroplasia families were not linked to the FGFR-3 locus, thus supporting clinical heterogeneity of this condition. In thanatophoric dwarfism (TD), a recurrent FGFR-3 mutation located in the second tyrosine kinase (TK 2) domain of the receptor was originally detected in 100% of TD II cases, our series seven distinct mutations in three different protein domains were identified in 25 of 26 TD I patients, suggesting that TD, like achondroplasia, is a genetically homogenous skeletal disorder. © 1996 Wiley-Liss, Inc.     

Radiological and histological variants of thanatophoric dysplasia are associated with common mutations in FGFR-3

We describe two fetuses of the 21st week of gestation that share some macroscopic, radiologic, and histologic findings of thanatophoric dysplasia (TD), but also show distinct differences from the usual subtypes of TD. These differences mainly comprise the lack of facial abnormality, only mild reduction of chondrocyte proliferation and hypertrophy, and the lack of fibrous tissue interposition between cartilage and periosteal bone. Thus, these two cases may represent a distinct variant of thanatophoric dysplasia. The molecular analysis of the FGF-R-3 gene demonstrated in both cases mutations which were not significantly different from those of other cases of TD. Thus, the phenotypic modulation within the subtypes of TD may be influenced by additional and yet unknown factors. © 1996 Wiley-Liss, Inc.     

Microcephalic osteodysplastic dwarfism (Type ll-like) in siblings

We report about two sibs showing a common pattern of birth defects, with a pedigree suggestive of autosomal recessive heredity. The main features are intrauterine growth failure with very low birthweight; disproportionate dwarfism with predominantly distal shortening of limbs; small cubitally inclined clenched hands; microcephaly with Seckel-like facies and delayed psychomotor development. X-ray findings include metaphyseal flare, V-shaped femoral metaphyses and bowing of forearms. Primordial microcephalic osteodysplastic dwarfism Type II is discussed. Metabolic and nutritional data are presented and discussed.     

Two Japanese cases with microcephalic primordial dwarfism: Classical seckel syndrome and osteodysplastic primordial dwarfism type II

Summary A male infant with classical Seckel syndrome and a girl with osteodysplastic primordial dwarfism type II are described. The boy with classical Seckel syndrome had severe brain dysplasia, a finding hitherto unreported in patients with this syndrome. The patient with osteodysplastic dwarfism type II had skeletal abnormalities including lumbar scoliosis, a small and high pelvis, metaphyseal flaring of the distal radii and ulnae, V-shaped metaphyseal flaring of the distal femorae, and short metacarpals and phalanges. The mother of this girl was short, microcephalic, and had disproportionately short forearms and legs. In view of this, dominant inheritance of the disease was suggested.     

Studies of microcephalic primordial dwarfism II: The osteodysplastic type II of primordial dwarfism

We describe three unrelated patients with intrauterine growth retardation (IUGR) and nearly identical bone changes. In certain respects, they share similarities with the Seckel syndrome: small forehead, moderately prominent nose, micrognathia, pronounced intrauterine and postnatal growth retardation, microcephaly, and mental retardation. Differences from the Seckel syndrome include disproportionate shortness of forearms and legs in the first years of life, brachymesophalangy, brachymetacarpy I, V-shaped flare of at least the distal femoral metaphyses, triangular shape of the distal femoral epiphyses, a high and narrow pelvis, proximal femoral epiphysiolysis, and coxa vara. Hormone studies in two cases demonstrated no gross disturbances, especially no deficit of hGH and somatomedin. Two previously reported cases referred to as Seckel syndrome had nearly identical bone changes. The cause of this “new” type of IUGR remains unclear.     

In vitro studies on clonal growth of chondrocytes in thanatophoric dysplasia

Thanatophoric dysplasia (TD) is characterized by a disorganized growth plate with markedly reduced proliferative and hypertrophic cartilage zones. Therefore, we studied in vitro the proliferation rates of articular chondrocytes from five TD patients and age-matched controls in response to bFGF, IGF-I, IGF-II, and TGF-β1. In human fetal controls bFGF was the most potent growth factor. Clonal growth of articular chondrocytes in response to bFGF was reduced in two of five TD patients and slightly below the range of controls in a third case. Stimulation of chondrocyte proliferation by IGF I and II was reduced in the patient whose response to bFGF was most markedly impaired. The effect of TGF-β1 ranged from normal to slightly elevated values in TD fetuses. These results indicate heterogeneity of the underlying defects in TD. Low proliferative responses of chondrocytes to bFGF and IGF-I/II are likely to play a key role in the pathogenesis of some cases. In two of five patients studied, the mechanisms of bFGF and IGF-signal transduction are candidates for the primary molecular defect. © 1996 Wiley-Liss, Inc.     

Effect of paternal age in achondroplasia,thanatophoric dysplasia,and osteogenesis imperfecta

The paternal ages of nonfamilial cases of achondroplasia (AC) (n = 78), thanatophoric dysplasia (TD) (n = 64), and osteogenesis imperfecta (OI) (n = 106), were compared with those of matched controls, from an Italian Indagine Policentrica Italiana sulle Malformazioni Congenite and a South American Estudio Colaborativo Latinoamericano de Malformaciones Congénitas series. The degree of paternal age effect on the origin of these dominant mutations differed among the three conditions. Mean paternal age was highly elevated in AC, 36.30 ± 6.74 years in the IPIMC, and 37.19 ± 10.53 years in the ECLAMC; less consistently elevated in TD, 33.60 ± 7.08 years in the IPIMC, and 36.41 ± 9.38 years in the ECLAMC; and only slightly elevated in OI in the ECLAMC, 31.15 ± 9.25 years, but not in the IPIMC, 32.26 ± 6.07 years. Increased maternal age or birth order in these conditions disappeared when corrected for paternal age. Approximately 50% of AC and TD cases, and only 30% of OI cases, were born to fathers above age 35 years. For AC and TD, the increase in relative incidence with paternal age fitted an exponential curve. The variability of paternal age effect in these new mutations could be due, among other reasons, to the high proportion of germ-line mosaicism in OI parents, or to the localization of the AC gene, mapped to the 4p16.3 region, in the neighborhood of an unstable DNA area. © 1995 Wiley-Liss, Inc.     

Acromesomelic dwarfism: Manifestations in childhood

Acromesomelic dwarfism is a distinct condition characterized by short stature of the short limb type, with the hands and feet showing the most obvious deviations from normal. The forearm bones are usually disproportionately shorter than the other long tubular bones of the limbs. The intelligence is normal. Available data suggest autosomal recessive transmission. Characteristic clinical and radiographic features permit establishment of a confident diagnosis in the first year of life.     

Caroline crachami,the sicilian fairy: A case of bird-headed dwarfism

One of the most remarkable cases of extreme dwarfism on record is Caroline Crachami, the Sicilian Fairy. She was born in 1815, and was taken to London to be exhibited for money in 1824. Due to her proportional dwarfism, severe intrauterine growth retardation, and typical “bird-headed” profile, Caroline Crachami has by some been diagnosed as a case of the autosomal recessive Seckel syndrome. In this historical vignette, the Sicilian Fairy's life and death are presented in some detail using new material, and the problem of her correct diagnosis is discussed. © 1992 Wiley-Liss, Inc.     

Long-term survival in typical thanatophoric dysplasia type 1

Thanatophoric dysplasia (TD), a severe skeletal dysplasia, is virtually always lethal neonatally, although a few previous reports have documented survival up to 4.75 years. We present a patient with survival beyond age 9 years and summarize his growth, development and medical history. The common Arg248Cys mutation in the extracellular region of fibroblast growth factor receptor 3 (FGFR3) was identified, eliminating the possibility that his long-term survival is attributable to an atypical mutation. This patient (and at least one other TD long-term survivor) have a rare skin disorder, acanthosis nigricans, which also occurs in Crouzon syndrome when caused by a FGFR3 mutation. Therefore, any molecular model of the origin of acanthosis nigricans secondary to FGFR3 mutations must account for the association of diverse mutations and these cutaneous effects. Am. J. Med. Genet. 70:427–436, 1997. © 1997 Wiley-Liss, Inc.     

Occurrence of thanatophoric dysplasia type I (R248C) and hypochondroplasia (N540K) mutations in two patients with achondroplasia phenotype

We report two patients with clinical and radiological findings of achondroplasia, who had the most common FGFR3 mutation occurring in thanatophoric dysplasia type I and hypochondroplasia, respectively. Thanatophoric dysplasia is usually a lethal condition, but the patient carrying this mutation is alive and presents a medical history similar to that of patients with achondroplasia. The events leading to such a discrepancy between genotype and phenotype are unclear. These rare cases may influence an appropriate medical and genetic counseling. © 2001 Wiley‐Liss, Inc.     

Micromelic dwarfism with cone epiphyses,metaphyseal dysplasia,and vertebral segmentation defects

We present the clinical and radiological findings in a newborn male with severe micromelic dwarfism, short neck, short and narrow upper thorax, and brachydactyly. At the age of 1 year mental development is slightly retarded. The X-ray findings of severe vertebral segmentation defects and a generalized metaphyseal skeletal dysplasia did not lead to a final, conclusive diagnosis. The present patient may be the first example of a new type of micromelic spondyloepi-metaphyseal dysplasias. © 1996 Wiley-Liss, Inc.     

Primordial osteodysplastic dwarfism type I in association with corneal clouding: evidence for autosomal recessive inheritance

A newborn male, born to Turkish first cousins, presented with severe pre- and postnatal growth retardation. Weight was 800 g at term. Salient clinical features were dwarfism with moderate limb shortening, microcephaly, hirsutism, facial dysmorphism including prominent small cloudy eyes, large nose with high nasal root, retrognathism and low-set ears. Radiologic abnormalities included huge clavicles, dysplastic vertebrae and enlargement of proximal metaphyses with medial spurs.