Familial patent ductus arteriosus

Correlation between methyltetrahydrofolate reductase (MTHFR) polymorphisms and isolated patent ductus arteriosus in Taiwan

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C gene polymorphisms are associated with the risk of patent ductus arteriosus (PDA) congenital heart defects. This study aimed to determine the association of these polymorphisms in patients with isolated PDA and in non-PDA patients group without congenital heart disease.

METHODS

This retrospective case-controlled study was undertaken in 17 patients with isolated PDA and a control non-PDA group consisting of 34 subjects without congenital heart disease. MTHFR gene polymorphisms were analysed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). In addition, the genotype distribution of the MTHFR gene was compared among different ethnicities using the HapMap database.

RESULTS

In contrast to the MTHFR C677T polymorphism, differences in the MTHFR A1298C genotype were observed between the two groups (P=0.002); a greater proportion of the PDA patients had the MTHFR 1298CC and 1298AA genotypes as compared to the non-PDA control group. After merging the data obtained from the Taiwanese participants with that from the HapMap database, genetic diversity of the MTHFR 1298AA genotype was observed.

CONCLUSIONS

Thus, the MTHFR A1298C polymorphism is associated with isolated PDA in Taiwan. Larger studies are necessary to evaluate the prognostic value of determining MTHFR polymorphism in PDA.

Patent arterial duct

Patent arterial duct (PAD) is a congenital heart abnormality defined as persistent patency in term infants older than three months. Isolated PAD is found in around 1 in 2000 full term infants. A higher prevalence is found in preterm infants, especially those with low birth weight. The female to male ratio is 2:1. Most patients are asymptomatic when the duct is small. With a moderate-to-large duct, a characteristic continuous heart murmur (loudest in the left upper chest or infraclavicular area) is typical. The precordium may be hyperactive and peripheral pulses are bounding with a wide pulse pressure. Tachycardia, exertional dyspnoea, laboured breathing, fatigue or poor growth are common. Large shunts may lead to failure to thrive, recurrent infection of the upper respiratory tract and congestive heart failure. In the majority of cases of PAD there is no identifiable cause. Persistence of the duct is associated with chromosomal aberrations, asphyxia at birth, birth at high altitude and congenital rubella. Occasional cases are associated with specific genetic defects (trisomy 21 and 18, and the Rubinstein-Taybi and CHARGE syndromes). Familial occurrence of PAD is uncommon and the usual mechanism of inheritance is considered to be polygenic with a recurrence risk of 3%. Rare families with isolated PAD have been described in which the mode of inheritance appears to be dominant or recessive. Familial incidence of PAD has also been linked to Char syndrome, familial thoracic aortic aneurysm/dissection associated with patent arterial duct, and familial patent arterial duct and bicuspid aortic valve associated with hand abnormalities. Diagnosis is based on clinical examination and confirmed with transthoracic echocardiography. Assessment of ductal blood flow can be made using colour flow mapping and pulsed wave Doppler. Antenatal diagnosis is not possible, as PAD is a normal structure during antenatal life. Conditions with signs and symptoms of pulmonary overcirculation secondary to a left-to-right shunt must be excluded. Coronary, systemic and pulmonary arteriovenous fistula, peripheral pulmonary stenosis and ventricular septal defect with aortic regurgitation and collateral vessels must be differentiated from PAD on echocardiogram. In preterm infants with symptomatic heart failure secondary to PAD, treatment may be achieved by surgical ligation or with medical therapy blocking prostaglandin synthesis (indomethacin or ibuprofen). Transcatheter closure of the duct is usually indicated in older children. PAD in preterm and low birth weight infants is associated with significant co-morbidity and mortality due to haemodynamic instability. Asymptomatic patients with a small duct have a normal vital prognosis but have a lifetime risk of endocarditis. Patients with moderate-to-large ducts with significant haemodynamic alterations may develop irreversible changes to pulmonary vascularity and pulmonary hypertension.

Familial occurrence of patent ductus arteriosus

We describe 7 relatives with patent ductus arteriosus (PDA) and a slightly unusual facial appearance with prominent midface with nose elongation and flattening of the nasal bridge, wide-set eyes, downturned palpebral fissures, mild ptosis, thickened lips, and apparently slightly low-set ears. Autosomal dominant inheritance is suggested in this family. Other families where affected members have PDA and a similar facial appearance and autosomal dominant inheritance were described previously by Char [1978: BD:OAS XIV (6B):303-305] and Temple [1992: Clin Dysmorphol 1:17-21].

Patent ductus arteriosus involving three generations--a case history

The authors present a family with patent ductus arteriosus (PDA) involving three generations, in the absence of consanguinity.

A large family with patent ductus arteriosus and unusual face

A large family is described in which patent ductus arteriosus in association with an unusual facial appearance affected nine family members in three generations. The segregation pattern suggests autosomal dominant inheritance with incomplete penetrance with respect to the PDA. The facial features included a broad, high forehead, flat profile, and short nose with a broad, flattened tip.

Familial persistent ductus arteriosus

The occurrence of isolated persistent ductus arteriosus in three generations of one family with surgical correction is described. The high incidence of the malformation in this family suggests autosomal dominant inheritance rather than a polygenic mode of inheritance.