Some chondrodysplasias with short limbs: molecular perspectives

A table of molecularly defined chondrodysplasias with short limbs is provided. Several are discussed in detail, including osteogenesis imperfecta and type I collagen mutations, Jansen metaphyseal chondrodysplasia and parathyroid hormone/parathyroid hormone-related protein receptor mutation, and chondrodysplasias caused by fibroblast growth factor receptor 3 mutations. The latter group includes achondroplasia, hypochondroplasia, thanatophoric dysplasia (types 1 and 2), San Diego platyspondylic dysplasia, and SADDAN.     

Lethal neonatal chondrodysplasias in the west of scotland 1970–1983 with a description of a thanatophoric,dysplasialike, autosomal recessive disorder,glasgow variant

Complete ascertainment of lethal neonatal short-limb chondrodysplasias was attempted in the West of Scotland for the period 1970–1983. Forty-three cases were identified, representing a minimum incidence of 1 in 8,900. The differential diagnosis included 11 well-delineated skeletal dysplasias, one case of warfarin embryopathy, and one apparently new condition with presumed autosomal recessive inheritance that has radiographic similarities to those of thanatophoric dysplasia (TD). In this series TD had an incidence of 1 in 42,221, which is consistent with new dominant mutation at a rate of 11.8 ± 4.1 × 10^?6 mutations per gene per generation. Ultrasonic measurement of fetal long bone length was performed in eight subsequent pregnancies at risk. Five unaffected fetuses were predicted correctly and three affected fetuses were detected during the second trimester (one with rhizomelic chondrodysplasia punctata—second trimester prenatal diagnosis not previously reported; one with achondrogenesis type II; and one with the new lethal condition).     

Lethal form of chondrodysplasia punctata with normal plasmalogen and cholesterol biosynthesis

We present a male autopsied case of chondrodysplasia punctata with abnormal face, symmetrical proximal limb shortness, severe psychomotor developmental delay, respiratory muscle weakness, and death at the age of 2 years. Although his clinical manifestations were similar to those of rhizomelic chondrodysplasia punctata (RCDP), biochemical studies using skin fibroblasts did not document the peroxisomal dysfunction described in RCDP. In addition, the sterol profile, for which abnormalities have recently been reported in cases of X-linked dominant form chondrodysplasia punctata (CDPX2), was normal both in the liver and in the fibroblasts. This patient may represent a new lethal form of chondrodysplasia punctata.     

Birth prevalence rates of skeletal dysplasias

This study establishes the prevalence rates at birth of the skeletal dysplasias which can be diagnosed in the perinatal period or during pregnancy. Using a population-based register of congenital anomalies, a prevalence rate of 3.22 0/000 was observed. The most frequent types of skeletal dysplasia were achondroplasia and osteogenesis imperfecta (0.64 0/000, 1/15,000 births), thanatophoric dysplasia and achondrogenesis (0.28 0/000). The mutation rate for achondroplasia was higher in our material than in the other studies: 3.3 x 10(-5) per gamete per generation. Our study demonstrates that prenatal diagnosis by ultrasound is possible in some skeletal dysplasias.     

Urinary amino acids and organic acids in the Sjögren-Larsson syndrome

Cataracts are suggested as a diagnostic marker to differentiate between the three types of chondrodysplasia punctata so far known. Both the rhizomelic and the X-linked dominant types are associated with cataracts in about two-thirds of the cases. In the rhizomelic type, the opacities tend to be bilateral and symmetrical. In the X-linked dominant type they are usually asymmetrical and often unilateral. In contrast, the consistent lack of cataracts is characteristic of the autosomal dominant type of chondrodysplasia punctata.     

Thanatophoric dysplasia in monozygotic twins discordant for cloverleaf skull: Prenatal diagnosis,clinical and pathological findings

We present male monozygotic twins with thanatophoric dysplasia (TD) type I concordant for long bone abnormalities and discordant for cloverleaf skull. The twins were the product of the second pregnancy of unrelated parents, with advanced paternal age. Prenatal diagnosis and postmortem examination showed severe rhizomelic shortness of limbs, bowing of the long bones with “telephone-receiver” femora in both twins, and cloverleaf skull and hydrocephalus in one of them. It is now accepted that most of cases of TD, such as in the present report, represent an autosomal dominant mutation with a high new mutations rate.     

Asymmetric and symmetric long bone bowing in two sibs: An apparently new bone dysplasia

We describe 2 sibs, one with congenital asymmetric long bone bowing and one with congenital symmetric long bone bowing. Other bony abnormalities in these sibs include beaten metal appearance of the skull, dolichomacrocephaly, ocular hypertelorism, and anterior beaking and bone-within-bone appearance of vertebrae. A differential diagnosis including campomelic dysplasia, kyphomelic dysplasia, hypophosphatasia, Grant syndrome, and osteogenesis imperfecta, and a discussion of potential mechanisms of long bone bowing are presented. The condition that these sibs have shares some characteristics of the above bone disorders, but appears to be a separate entity which to our knowledge has not been described previously. © 1993 Wiley-Liss, Inc.     

Generalized chondrodysplasia punctata with shortness of humeri and brachymetacarpy: humero-metacarpal (HM) type: variation or heterogeneity?

We report on a girl with symmetrical rhizomelic shortness of the upper limbs and punctate epiphyseal calcifications noted at birth. Presumably she has normal height, but short nose, short hands, and normal mentation; and on roentgenograms short and wide humeri, symmetrical brachymetacarpy, especially of the 4th metacarpals, and hypoplastic distal phalanges, sagittal clefting of vertebral bodies, and punctate calcifications at various areas including the entire spine, sacrum, hands, feet, trachea, and thyroid cartilage. It is an apparently new syndrome of chondrodysplasia punctata (CP), quite distinct from the classic form (Conradi-Hünermann type), as well as the other well-defined forms of CP. We thus suggest the term chondrodysplasia punctata, humero-metacarpal (HM) type.     

Addendum

Autopsy records from the Women and Infants' Hospital from January 1974 through January 1994 were reviewed to identify cardiac malformations in the presence of skeletal dysplasia. Of 24 cases of lethal fetal or neonatal osteochondrodysplasias, 4 were given diagnoses in which disorders of type II collagen are regarded as causative. These 4 were categorized in the spondyloepiphyseal dysplasia (SED) spectrum of disorders; specifically two patients with hypochondrogenesis and two with spondyloepiphyseal dysplasia congenita were identified. Defects in cardiac septation were noted in the 2 patients with hypochondrogenesis. No cardiovascular abnormalities were present in the remaining cases, which included thanatophoric dysplasia, osteogenesis imperfecta, and asphyxiating thoracic dystrophy. Although cardiovascular malformations have been described in other types of osteochondrodysplasias, e.g., short rib polydactyly syndrome type II and chondroectodermal (Ellis van Creveld) dysplasia, congenital heart disease has not been described in hypochondrogenesis. Type II collagen, which has been found to be abnormal in some patients with hypochondrogenesis, is considered to have a limited tissue distribution, and has not been detected as yet in human myocardium. The findings presented here suggest that type II collagen may function in human cardiogenesis. © 1995 Wiley-Liss, Inc.     

Evaluation of prenatal-onset osteochondrodysplasias by ultrasonography: a retrospective and prospective analysis

The osteochondrodysplasias or skeletal dysplasias are a heterogenous group of over 350 distinct disorders of skeletogenesis. Many manifest in the prenatal period, making them amenable to ultrasound prenatal diagnosis. A retrospective analysis evaluated 1,500 cases referred to the International Skeletal Dysplasia Registry (ISDR) to determine the relative frequency of specific osteochondrodysplasias and correlation of ultrasound versus radiographic diagnoses for these disorders. Within the retrospective cohort of 1,500 cases, 85% of the referred cases represented well-defined skeletal dysplasias, and the other 15% of cases were a mixture of genetic syndromes and probable early-onset intrauterine growth restriction. The three most common prenatal-onset skeletal dysplasias were osteogenesis imperfecta type 2, thanatophoric dysplasia and achondrogenesis 2, accounting for almost 40% of the cases. In a prospective analysis of 500 cases using a standardized ultrasound approach to the evaluation of these disorders, the relative frequencies of osteogenesis imperfecta type 2, thanatophoric dysplasia and achondrogenesis 2 were similar to the retrospective analysis. This study details the relative frequencies of specific prenatal-onset osteochondrodysplasias, their heterogeneity of prenatal-onset skeletal disorders and provides a standardized prenatal ultrasound approach to these disorders which should aid in the prenatal diagnosis of fetuses suspected of manifesting skeletal dysplasias.