De novo 17q paracentric inversion mosaicism in a patient with Beemer-Langer type short rib-polydactyly syndrome with special consideration to the classification of short rib polydactyly syndromes

Short rib polydactyly syndrome type 3 with absence of fibulae (Verma-Naumoff syndrome)

Short rib polydactyly syndrome (SRPS) is a group of skeletal dysplasias manifested by short-limb dwarfism, short ribs with thoracic dysplasia and polydactyly. SRPS is an inherited autosomal-recessive disorder with different prenatal sonographic and postnatal clinical, histological and radiologic findings. SRPS type 1 (Saldino-Noonan) and type 3 (Verma-Naumoff) are very similar and frequently get mixed. In this report, we present a case of SRPS with hydrops, thoracic hypoplasia, short limbs and postaxial polydactyly in a 27-week fetus. The visceral findings in the fetus including the central nervous system were normal. The karyotype was 46XY. The prenatal diagnosis was thought to be type 1 because of the absence of fibulae at ultrasonography. However, postmortem autopsy, histologic, and radiologic findings were reviewed and the diagnosis was type 3 SRPS because of absence of visceral anomalies, presence of fan-shaped iliac bones and short tubular bones with metaphyseal widening. We concluded that detailed ultrasonography performed in the prenatal period is very important in the diagnosis and differential diagnosis of SRPS.

Short rib-polydactyly syndrome

INTRODUCTION

Short rib-polydactyly syndrome (SRPD) is an autosomal recessive, lethal skeletal dysplasia. It is characterized by short limb dwarfism, short ribs with thoracic hypoplasia, polydactyly, and multiple anomalies of major organs.

CASE REPORT

We report a case of SRPD subtype II (Majewski) that was detected in the 36th week of gestation, showing hydropic change, narrow thorax, shortened limbs, protuberant abdomen, micromelia, polydactyly and extremely low set ears, depressed nasal bridge, and cleft palate. The family was informed of the fatal outcome of the condition. Delivery was induced, and the baby died just after the birth.

DISCUSSION

Prenatal diagnosis is established with postmortem radiographic and pathologic examinations.

Diagnostic dilemmas in the short rib-polydactyly syndrome group

The short rib-polydactyly syndromes are a group of lethal skeletal dysplasias with autosomal recessive inheritance characterized by markedly short ribs, short limbs, usually polydactyly, and multiple anomalies of major organs. At least four types have been recognized. The radiological findings of 10 cases are presented. Each fetus or stillbirth has some of the radiological features of the four established types of short rib-polydactyly syndrome and raises diagnostic dilemmas in differentiating these entities. The overlapping phenotypes of these fetuses supports the previously suggested hypothesis that the different subtypes of the short rib-polydactyly syndrome group are not single entities, but rather part of a continuous spectrum with variable expressivity.

New case of Beemer-Langer syndrome

We present the case of a male infant born at 37 weeks gestation with multiple congenital anomalies, including hydrops fetalis, facial and visceral abnormalities, short ribs, and short limbs without polydactyly. We believe that this represents a further case of the Beemer-Langer syndrome, a relatively recently described form of lethal osteochondrodysplasia with an autosomal recessive mode of inheritance. This case also showed some less frequently described anomalies, including arachnoid cysts of the brain and short intestines.

Short rib-polydactyly syndrome: more evidence of a continuous spectrum

We report a fetus with radiological features of the four established types of short rib-polydactyly syndrome (SRPS). The phenotype of this fetus supports the previously suggested hypothesis that the different subtypes of the short rib and polydactyly syndrome are not single entities, but rather, part of a continuous spectrum with variable expressivity.

Identification and mapping of human histone acetylation modifier gene homologues

The products of histone acetyltransferase and deacetyltransferase genes regulate histone acetylation in eukaryotes, thereby regulating access of transcription factors to chromatin and modulating gene expression. Histone acetylation modifiers have been found to participate as cofactors in diverse mammalian transcriptional complexes involved in regulation of cellular proliferation and differentiation. A role for histone acetylase has been implicated in leukemias and developmental disorders. To gain insight into a role of additional potential histone acetylation modifier genes in human disease, we identified six histone acetyl-transferase or deacetyltransferase homologues using the dbEST database, and we mapped, using high-resolution FISH, a total of five family members to 1p34.3, 6q21-q22, 5q31, 3p24, and 17q21. We then identified human genetic disorders for which candidate genes are not yet known and that have been mapped to the same chromosomal regions as the histone acetylation modifiers. This analysis may help identify new candidate genes for human diseases that involve disturbances of histone acetylation.

The structure and chromosome location of the human chondroadherin gene (CHAD)

The cDNA sequence of the human chondroadherin gene was cloned using PCR-based techniques. The gene encodes a protein of 359 amino acids, of which the first 21 amino acids represent a putative signal peptide sequence and which possesses 11 leucine-rich repeats flanked by cysteine-rich regions. The cDNA possesses a 5' untranslated region of 149 bp, a coding region of 1080 bp including the stop codon, and a 3' untranslated region of 561 bp terminating in a poly(A) tail. The cDNA hybridizes with a single messenger RNA of 1.9 kb, which is present in chondrocytes at all ages. Analysis of genomic DNA revealed that the chondroadherin gene possesses two introns, both of which reside within the coding region. The first intron has a length of about 2.3 kb and separates the codons for lysine(258) and phenylalanine(259). The second intron has a length of about 0.5 kb and splits the codon for tryptophan(314). This genomic organization results in exon 1 encoding the signal peptide, the amino-terminal cysteine-rich region, and the first 9 leucine-rich repeats; exon 2 encoding the last 2 leucine-rich repeats and part of the carboxy-terminal cysteine-rich region; and exon 3 encoding the remainder of the carboxy-terminal cysteine-rich region. The gene does not possess a TATA box prior to its transcription start site. Isolation of a cosmid clone spanning the chondroadherin gene enabled its chromosome location to be established. The gene was shown to reside at chromosome 17q21.33.

Short rib-dysplasia group (with/without polydactyly): report of a patient suggesting the existence of a continuous spectrum

We report on a patient with manifestations typical of Mohr syndrome and of the short rib (polydactyly) syndromes (SR(P)S) Majewski, Verma-Naumoff, Beemer, and Jeune. It seems possible that the different types of SR(P) syndromes, rather than being distinct conditions, are part of a large disease spectrum. The frequent overlap between orofaciodigital syndromes and SR(P) syndromes may be interpreted as the outcome of deletions of different size within the same chromosome region.