Dk Phocomelia Syndrome

Clinical Features

Cherstvoy et al. (1980) referred to a case reported by workers in Kiel and described an apparently identical case of a syndrome of phocomelia, thrombocytopenia, encephalocele and urogenital abnormalities. They called it the 'DK phocomelia syndrome' from the surname of the 2 patients.

Bird et al. (1994) described a female fetus with manifestations of DK phocomelia syndrome (occipital encephalocele, cleft palate, absence of the left radius and digits 1 and 2 of the left hand, single horseshoe kidney, anal atresia, abnormal branching of coronary arteries, abnormal lobation of the lungs) and diaphragmatic agenesis. Her brother had diaphragmatic agenesis, omphalocele, accessory spleen, abnormal lobation of the lungs, and absence of papillary muscles in one leaflet of the tricuspid valve. Diaphragmatic agenesis was the only primary defect common to both sibs. Bird et al. (1994) suggested that this family provides evidence for an autosomal gene controlling the morphogenesis of midline structures.

Brunetti-Pierri et al. (2004) reported a 16-month-old patient with meningoencephalocele, absence of the radii, ambiguous genitalia, and transient neonatal thrombocytopenia. Thrombocytopenia was present during the first 2 weeks of life but not found on subsequent testing. Despite the neonatal complications and meningoencephalocele, the patient later had normal psychomotor development.

Cytogenetics

Bamforth and Lin (1997) reported a case in which the patient had normal lymphocyte chromosomes but was mosaic in fibroblasts for deletion of 13q12. All previously reported cases of DK phocomelia had been reported as having a normal chromosomal constitution. The proposita was an 8-year-old girl who had a small parietooccipital encephalocele in the midline at birth as well as asymmetry of the face with flattening of the right side and elevation of the right ear. There was absence of the right fifth finger, hypoplasia of the thumb, and a single, palmar crease. On the other side there was hypoplasia of the fifth finger with dislocation and normal-sized thumb. The hips were dislocated. By 15 months of age, the facial asymmetry had resolved. Renal pelviureteric junction obstruction required surgical relief. When her hair started to grow, she had bald patches. At the age of 9 years, the child developed seizures. There was a wide gap between the central incisors.

Population Genetics

Bermejo-Sanchez et al. (2011) reported epidemiologic data on phocomelia from 19 birth defect surveillance programs, all members of the International Clearinghouse for Birth Defects Surveillance and Research. Depending on the program, data corresponded to a period from 1968 through 2006. A total of 22,740,933 live births, stillbirths, and, for some programs, elective terminations of pregnancy for fetal anomaly were monitored. After a detailed review of clinical data, only true phocomelia cases were included. Descriptive data were presented and additional analyses compared isolated cases with those with multiple congenital anomalies (MCA), excluding syndromes. Bermejo-Sanchez et al. (2011) also briefly compared congenital anomalies associated with nonsyndromic phocomelia with those presented with amelia (see 601360), another rare severe congenital limb defect. A total of 141 phocomelia cases registered gave an overall total prevalence of 0.62 per 100,000 births (95% confidence interval 0.52-0.73). Three programs, Australia Victoria, South America ECLAMC, and Italy North East, had significantly different prevalence estimates. Most cases (53.2%) had isolated phocomelia, while 9.9% had syndromes. Most nonsyndromic cases were monomelic (55.9%), with an excess of left (64.9%) and upper limb (64.9%) involvement. Most nonsyndromic cases (66.9%) were live births; most isolated cases (57.9%) weighed more than 2,499 grams; most MCA (60.7%) weighed less than 2,500 grams and were more likely stillbirths (30.8%) or terminations (15.4%) than isolated cases. The most common associated defects were musculoskeletal, cardiac, and intestinal.